HomeMy WebLinkAboutAPA2854dALASKA DEPARTMENT OF FISH AND GAME
SUSlTNA HYDRO AQUATIC STUDIES
ADDENDUM TO REPORT NO, 3, CH, 8
Prepared far:
ALASKA POWER AUTHORITY
334 W. Fl-H AVE,
ANCHORAGE, ALASKA 9Q50 1
PREFACE
This report is an addendum to one of a series of reports prepared for
"cke Alaska Power Authority (APA) by the Alaska Dep3rtment of Fish and
Game (ADF&G to provide information to be used in evaluating the
feasi bil i ty of the proposed Susi tna Hydroelectric Project. The ADF&G
Susitna Hydro Aquatic Studies program was initiated in November 1980.
Reports prepared by the ADF&G prior to 1983 on this subject are
available from the AM.
This addendum revises and supplements portions of Chapter 6 of the 1984
ADF&G Su Hydro Studies Report Number 3, An Evaluation of Passas
Conditions for Adult Salmon in Slou~hs and Side Channels of the Middle
Susi tna River. This addendum provides the n~ost current information on
passage requirements for salmon based on the presently available
information. The need for reevaluation of previous1 y establ i shed 1 ocal
flows and mainstem discharges required for successful and unsuccessful
salmon passage at selected slough and side channel sites in the middle
reach of the Susitna River (RM 95 to 152) was necessitated based on an
assessment of the results of the 1984 Passage Validation Studies (PVS
In addition, a review of presently available passage related data
indicated that col lection of additional data, or further evaluations of
existing data, were needed to more adequately assess salmon passage
conditions in these habitats. Results of the 1984 PVS, which were
previously presented in a draft techntcal memorandum from A. Bingham to
J. Fergerson (November 30, 1985 have been incorporated into this
addendum along with all revised and updated data.
Addendum to Alaska Department of Fish and Game
Report No. 3, Chapter 6:
Salmon Passage Validation Studies
August - October, 1984
Jeffery S. Blakely
and
Joseph 5. Sautner
Alaska Department of Fish and Game
Susi tna Hydro Aquatic Studies
620 East 10th Avenue
Anchorage, A1 aska 99501
and
Larry A. Rundquist
and
h. El izabeth Bradley
Entrix, Inc.
4794 Business Park Boulevard
Suite 6
Anchorage, Alaska 99503
ABSTRACT
An interim evaluation of the effects that mainstem discharge and local
flow have on passage conditions for adult chum and sockeye salmon at
selected slough and side channel habitats of the middle reach of the
Susi tna River was previously presented in Sautner et a1 . 1984) Due to
the 1 imited data avai labie for this interim evaluation, additional data
DRAFT
were collected during the 1984 open water Field season to reevaluate the
passage criteria and the local flow and mainstem discharge values
required for successful and unsuccessful salmon passage within these
habilats. In addition, the methodologies used for the backwater and
local Plow analyses were revised to reflect the addizional data which
were collected,
A Passage Validation Study PVS) was initiated during the 1984 open
water field season to collect additional physical and biological data to
more accurately assess salmon passage conditions within slough and side
channel habitats of the middle Susitna River. Physical data collected
incl uded channel cross section and thal weg profiles, substrate assess-
ments, and local flow measurements. Biological data consisted of salmon
passage criteria based on visual observations of adult chum salmon
movement in selected slough and side channel habitats, The salmon
passage criteria and passage reach evaluations previously presented in
Sautner et al. (1984) were reevaluated and revised based on these data
using a modified analytical approach. The revised analysis resulted in
the devel~pment of a single set of salmon passage criteria thresholds
for defining successful and unsuccessful passage conditions at study
si tes,
Using the revised criteria thresholds as a guidelines, 85 passage
reaches were identified at slough and side channel sites during the 1984
PVS compared to 74 passage reaches identified in Sautner et al. (1984).
A reevaluation of the breaching, backwater, and local flohg analysis for
these passage reaches indicates that mainstem discharge and local flow
requirements for SUCC~SS~U~ and unsuccessful passage are simflz~ to
values previously established. The most significant differ2nces
occurred in the backwater analysis some sites, where required
mainstem discharges decreased over 1,000 cfs. kiater depth was
determined to be the primary physical variable affecting passage
conditions at passage reaches; passage conditions were not greatly
affected by changes in passage reach length. Variations in channel
configuration and substrate size were assumed to have no influence on
the salmon passage criteria. The revised passage criteria thresholds
are based on an upper thalweg depth of 0.5 feet thereby voiding all
previous analyses that utilized 0.67 feet as the upper limit of thalweg
depth.
TABLE OF CONTENTS --
TABLE
LIST OF FIGURES e~ee~aoo~Q~~@Q~aBQaQ61QO@~O~OOP1QC)B@QQQ~aoBQ
LIST OF APPENDIX F~GURESeQ~~eee~a~eeoB)BeBeae~OQg)O~Qa(BeBeeaQoa vii
LIST OF TABLESoQaQ~~~~eee~Q~BFP~~D(fOOo(IeOeQ0s~WBaQes~e~oa xiv
LIST OF APPENDIX TABLES eeeOoee~~O~~~~QaB(OQ8D61~aQm~BO~C1~OooeaQQ xvi
1.1 Background ~~~~~~o~aaoQO~oe~9(P~eoeQO(PBIeBe~e~aQ~a~~ae~e~~~e~eQ
1.2 Objectives e~e~~~oQ~eooa~(ZBQe~~aee~eOeoQ~a~~Q~~oe~Q~eeeQ~~eaQa
2,6 METHODS QQe~~eQ~~Beo~eDeaO~~eeBO0BO~agb)OB~61~Q~~~Q~61~QQ~e~~~O~~~Q 6
2,1 Site Selection ~BaQeODeD6161~DOseeeOOd)t)QQIDOOOO@QeQ61Qe~~eeeee~~e 6
2.2 Field Methods........., ~eOeIsOcbeWe8~esO~e~O~Q~Q~~e~~~eQo~~oe 6
2,Z.I Determination of Salmon Passage Criteria.o.a....o..ea~.Q 6
2,2.2 Identification of Passage Reaches ~~61~soo~~B~QBBe~B80Ba~a 10
2.2.3 Physical Habitat Variables Used to Evaluate
Passage Reach Conditions aoea~e~eoQ~~~OQgeeeBBBe(De~eesPe 12
Analytical
2.3.1 Salmon Passage Criteria.... ee610~~eBBa8)eOBQ~QaBOdePBOOe0 15
2.3.2 Passage Reach Evaluations ~~oe~e61QO~OoeOooe~QQaOCea~OQQe 18
2.3.2.1 Verification of Passage Reaches... e61Qe@e.e.0B)9RaBOa0 20
2.3.2.2 Breaching Analysis FP~~~61e61QQ5~~bB~~eOaQQBdr(DBdB)e@~Oaa 21
2.3.2.3 Backwater Analysis ~~Booe~e~~QI)DdOC)PeoeoOU)ODoQeOeQBQ 21
2.3.2.4 Local Flow Analysis ~~Qee61e~eeeUc~eOeOo~O~a~~o~QB)aQ0 22
3.0 RESULTS ~61BB~a~~e~~~OOB~DsD8BBoOOLB~~8sOOsmoBQ 27
3.1 Salmon Passage Criteria... aOQ~@~~~DO~Q~C~QaB~e8a(DQe08Q8mQQe0 27
3.2 Passage Reach Evaluations ~e~~a~a~Qe~eQQaeOQeBQ~Oe(gC~BPoeea 36
3.2.1 Breaching and Backwater Analyses Q~Q~~~oQaQe~~Oe~QeDseOQo 36
3.2.2 Local Flow Analysis ........... ~~Be.Q..00BIBOQ~61~B.~e.. 44
4.1 Salmon Passage Criteria.. . . . . . . . . . . . . . e . . @ . a . . @ . 52
4.2 Passage Reach Evaluations .... .~....e...gQ..~e.,L.OQR.b)~eO.l 56
4.2.1 Mainstem Breaching ~Q.@~.~~~@~OB,DO~~BI)~~~~d94)o@cbP~Q@Q 57
4.2.2 Mainstem Backwater. ..... @a~~~~(BeBd&Ooab~e~~c~@Qe(O~"d~eQ~ee~ 59
4.2.3 Local Flow ........ . ...... ....~...B.e(Pa8.....a.ea...o. 61
4.3 Influence of Mainstem Discharge on Local Flows.. . . . . . . . . . . . . 66
4.4 Concl usi ons/Recomendati ons.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.0 CONTRIBUTORS ~OO~e~~~O~~B~~~Q~a(B~Om~~~Q~~OQOOeQ 72
6,Q ACKNOWLEDGEMENTS,..S....~.B.b.(O.OO..0.Ds...D...e..e.~e 73
7.0 LITERATURE C%TEDee0.e~...ee..~e.eo~e.~e~~e..eeoaoo~ee 74
8,O APPEND%CESMee.ee..~oe~e~~eueo~~~e~~~~eg,eec 76
Appendix A. Suppl ement to Local Fl ow Methods. . . . . . . . . . . . . . . . . A-l
Appendix B. Passage Reach Di stri bution Maps.. . . . . . . . . . . . . . ... B-l
Appendix C. Thalweg Profiles of Passage Study Sites.. . , . . . . . . C-l
Appendix D. Gross Sectional Data..,.. ....................... D-l
Appendix E. Stage and Discharge Data.. ee@0..e..*ee@e8eeB)QOB6)@ E-l
:?lustraticn 0:' tne genera! procecure csed in
the local flow distribution artalysis.. ................. A-4
August Precipitation Duration Curve for the
period 1972-1981 at the Tsl keetna Llieather ....................... Station (Adapted from H-E 1984). A-17
APPENDIX 3
Locations of passage reacbes at Whiskers
Creek Slough during the 1984 open water
~~~~~~@E~E~*OB~~~O.~~O8DS~OD*B~~~0OO~@e@Q E-3
Locations of passage reaches at Mainstem 2
Side Channel during the 1984 open water
~$~~~~~e9~.~.D0Q.~.B.~..I..L)OP.D~.COO.iD0(P~.D... B-4
Locations of passape reaches at Slough 8A ............ (lower) during the 1984 open water season.. E-5
Locations of passage reaches at Slough 8A
(upper) during the 1984 open water season .............. 5-6
Locations of passage reaches at Slough 9
during the 1984 open water season... ................... E-7
Locations of passage reaches at Slough ?A
during the 1984 open water season..............D(I Be.... E-8
Locations of passage reaches at Side Channel
10 as identified by the thatweg profile ................ 3-9
Locations of' passage reaches at Slough I! and
Upper Side Channel !I during the !984 open
water seasonEe~,OOEe,.~,eCD.~OOaUIDeC.e..DODDe~. B-SO
Locations of passage reaches at Slough 19
during the 1984 open ~aier season.............., ........ E-::
Locations of passage reaches at Slouoh 20
during the 1984 open water season. ...................... 6-12
Locations of passage reaches at Side Channel
21 during the 1984 open water season........... ...I..... E-13
Locations of passage reaches at Slough ?!
during the 1984 open water season........... .....so.... F-14
locati(3ns of passage ~eaches at Slough 22
during the :984 open water season........,.. .......... E-.;?
LIST 0' APPENDIX FIGURES (Continued)
APPENDIX C
C-l Tkalweq profile of Whiskers Creek Slough
showing approximate locations of passage
reaches eUOBaeO~e800eQe~0sQ8oee~~~BQC1eBOQ~000e5OdO~aOQWL) . @-3
Tkalweg profile of Mainstem 2 Side Channel
showing approximate 1 ocations of passage
reaches BOQOOoeeBQQ0101g~~B~80Q(IO~eeOeQOeOOQe0 C-4
Thalweg profile of Slough 8A showing .......... approximate 1 ocations of passage reaches.. ... C-5
Thalweg profile of Slough 9 showing
approximate locations of passage reaches ............... C-6
Thalweg profile of Slough 9A showing
approximate locations of passage reaches ............... C-7
Thalweg profile of Side Channel 10 showing
approximate locations of passage reaches.. .......... ... C-8
Thalweg profile of Slough 11 showing
approximate 1 ocations of passage reaches.. .......... ... C-9
Thalweg profile of Upper Side Channel I1
showing approximate locations of passage
reaches as~~~~~e~e~a~~eO~s)d(sOOaeD(B80~eQBI)Q C-10
Thalweg profile of Slough 19 showing
approximate locations of passage rezches. .............. C-ll
Thalweg profile of Slough 20 showing
approximate locations of passage reaches ............... C-12
fhalweg profile of Side Channel 21 showing
approximate locations of passage reaches ............... C-13
Thalweg prof i le of Slough 21 showing
approximate locations of passage reaches ............... C-14
Thalweg profile of Slough 22 showing
approximate locations of passage reaches.. ......... .... 6-15
LIST OF APPENDIX FYGU2ES (Ccotinued)
Page
->-
APPENDIX D (Continuedl
Cross sectional profile of Passage Reach VIIR
in Slough 8A, October 6, 1984 .............a.e......lg... D-89
Cross sectional profile of Passage Reach
VIIIR in Slough 8A, October 7, 1984.................0bJa D-90
Cross sectional profile of Passage Reach IXR
in Slough 8A, October 7, 1984.. ........................ D-91
Cross sectional profile of Passage Reach XR
in Slough 8A, October 7, 1984 ...a...................... D-92
Cross sectional profile of Passage Reach IV
in Slough 9, September 22, 1984.. ...................... 0-93
Cross sectional profile of Passage Reach V in
Slough 9, September 22, 1984.. ......................... D-94
Cross sectional profile of Passage Reach I in
Slough 9A, October 8, 1984 ............................. D-95
Cross sectional profile of Passage Reach I I
...................... in Slough 9A, September 23, 1984. D-96
Cross sectional profile of Passage Reach III
in Slough 9A, September 23, 1984 .....................Is. D-97
Cross sectional profile of Passage Reach IV
in Slough 9A, September 23, 1984 ....................... D-98
Cross sectional profile of Passage Reach V in
Slough 9A, September 23, 1984. ~s~~~~~~m~e~~~eOema~~50u0 D-99
Cross sectional profile of Passage Reach VI
in Slough 9A, October 8, 1984 ~~~~.~~~~~~~~~~~~~~~~~~~~~~~~&g~
Cross sectional profile of Passage Reach VII
in Slough 9A, September 23, 1984 usm0.e~~~~@@s~sd05~sBQ~~~~~~
Cross sectional profile of Passage Reach VIiI
in Slough 9A, September 23, 1984 e*eee.*e..eQ*.~a600a~a8D~I02
Cross sectional profile of Passage Reach IX
in Slough 9A, September 23, 1984 e~~~0~~~~~~Q@~~QeQ90Q~~~D~~~
Cross sectional profile of Passage Reach X in
........... Slough 9A9 October 8% 1984 0~.eB,BDBUOBBedOBsOIf9gl~$4~
Cross sectional profile of Passage Reach III
in Side Channel 21, October 16, 1984.. ................ .D-121
Cross sectional profile of Passage Reach IV
in Side Channel 21, October 16, 1984.. ...............Be D-=H22
Cross sectional profile of Passage Reach VII
in Side Channel 21, October 15, 1984.. ................ *DggI23
Cross sectional profile of Passage Reach VIII
in Side Channel 21, October 15, 1984.. ................. D-124
Cross sectional profile of Passage Reach IX
in Side Channel 21, October 15, 1984.. .e5.@.....@.e... *D-125
Cross sectional profile of Passage Reach I in
Slough 21, October 15, 1984.. .......................... D-126
Cross sectional profile of Passage Reach II
in Slough 21, October 15, 1984 ~ee.enee.e~~~..WOe0BDaDB~DD127
Cross sectional profile of Passage Reach IIIR
in Slough 21, Octobe~ 15, 1984.. ....................O.. Dm128
Cross secfional profile of Passage' Reach I in
Slough 22, October 14, 1984 nQ~e~~e.~~~eeQ~~OOarbe~sQOe(slOB~fl,~~
Cross sectional prsfi le of Passage Reach II
in Slough 22, October 14, 1984.. ...................... .D-130
Cross sectional profile of Passage Reach I11
in Slough 22, October 14, 1984.. ...................... .D-131
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LIST OF TABLES
Table --
1 Summary of passage study sites and - corresponding river miles in the middle
Susitna R~v~~,,~~~.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 7
2 Substrate size classification system used for
the 1984 passage studies............eQ100~F99)~eBeO~e8gC18)g 14
3 A summary of chum salmon passage data
col Iected at passage reaches within slough
and side channel study sites in the middle
Susitzd River during the 1984 open water
reason.............meQ.eoBBO.eB.,meBQB.B.eBg. 28
A summary of middle Susitna River passage
reaches with selected physical character-
istics which were identified during the 1984
open water season. A cross reference 1 ist to
passage reaches defined in Sautner et al.
(1984) is included ..................................... 37
A summary of ini tiai breaching and con-
trol 1 ing mainstem discharges affecting
passage reaches within selected study sites
in the middle Susitna River .............Q.............. 40
Summary of mainstem discharges required to
provide successful and unsuccessful salmon
passage conditions from backwater effects at
selected study sites in the middle Susitna
River ~eBee~~e~e~o~BeeODeB~~eeBOOeeOe~e~eeeQaBmee 41
Summary of local flows required for success-
ful and unsuccessful passage conditions and
the frequencies of occurrence based on
precipi tat1 on and groundwater contributions
at an average Susitna River discharge of
15,000 cfs during the August 20 to September
20 period ~o@e~ee@~ae~@~BD~(DsD~~6,00QB~OOB~BQd)eQBeeB 47
Frequencies of occurrence of local flows
evaluated through the use of mainstem versus
local flow relationships in Sloughs 8A, 9 and
11 excluding the effects of backwater and
breaching ~~~~~~~e%eQeB~ee~ee~*OaPd~~~B~Q~eee 51
Comparison of the results of the backwater
analysis presented in this addendum to the
results previously reported in Sautner et ale
1984) for sloughs and side channels in the
middle Susitna River ....e.............................. 60
LIST' OF TABLES (Continued)
Comparison of the r*r:;ults of the local flow
analysis presented in this addendum to the
results previously reported in Sautner et ale
for sloughs and side channel:; in the
middle Susj tna Ri-ier,. . . . , . . . . , . . . . . . . . . . . . . . ,. , . . . . . . .
~ LIST OF APPENDIX TABLES
APPENDIX A
Percent groundwater f 1 ow values for sloughs
and side channels .5e~~~..~e~e~P~~bOQ~Bw~WaBB~ee~~0em A-5
Ranges of Manning's roughness coefficients as
a function of substrate size and channel
uniformity ..~~~~ee~lDO~OOQee~eO~cQDBiOIPOO~Q~~s~eee~eQ~~a~ A-9
Values of Manning's roughness coefficient,
energy gradient, and excluded flow For
calibration of Manning's equation ~o~..eee.~~eaBaoOOOB~e 8-12
Frequency of occurrence of local flows for
successful and unsuccessful passage for a
basef 1 ow correspond$ ng to 15,000 cf s Susi tna
River discharge at Gold Creek and including
precipitation from August 20 to September 20 ........... A-15
Precipitation coefficients for determining
precipitation values at selected sloughs
using precipitation values recorded at the
Talkeetna weather station (derived from R&M
B~~OQB~OQ~B~~B~~UBBQQQ~OBQBBB,OB~~~B~B~~~~~~~~~~~~~ a-19
Base flows for a mainstem discharge at Gold
.................................... Creek of 15,000 efs A-21
Summary of survey data collected for the
thalweg profile of Slough 19 during the 1984
open water field season..............BsQOeDD.OaeBaO~OOB C-16
APPENDIX D
Streambed profile ~f Passage Reach I in ............. Whiskers Creek Slough, October 4, 1984.. .. D-3
Streambed profile of Passage Resch II in ............. Whiskers Creek Slough, October 4, 1984.. .. 0-5
Streambed profile of Passage Reach I in
Mainstem 2 Side Channel, October 5, 1984 ............... D-6
Streambed profjle of Passage Reach I1 in ............... Mainstem 2 Side Channel, October 5, 1984 D-7
Streambed profile of Passage Reach III in
Mainstem 2 Side Channel, October 5, 1984.. ............. D-9
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LIST OF APPENDIX TABLES (Continued)
Table
APPENDIX D
Streambed profile of Passage Reach VI in
Slough 19, October 17, 1984.. .......................... 0-52
Streambed profile of Passage Reach VII in
............................ Slough 19, October 17, 1984 D-53
Streambed profile of Passage Reach VIII in
Slough 19, October 17, 1984.. .......................... D-54
Streambed profile of Passage Reach IX in
Slough 19, October 17, 1984.. .......................... D-55
Streambed profile of Passage Reach I in
Slough 20, October 17, 1984.. ................O......... D-56
Streambed profile of Passage Reach VI in
Slough 20, October 17, 1984.. ...................a.QB... D-57
Streambed profile of Passage Reach I in Side
Channel 21, October 16, 1984 %Qeee.~~~Q~~e~~~~BQ~mg~@alDa D-58
Streambed profile of Passage Reach II in irde
Channel 21, October 16, 1984 ~~e~~Q~.~~.~.e@Q~~R~a~Qe~~~ D-59
Streambed profile of Passage Reach III in
Side Channel 21, October 16, 1984 @.~.~e.ee.B.0e~61e~OeOB D-60
Streambed profile of Passage Reach IV in Side
Channel 21, October 16, 1984 ........................... D-61
Streambed profile of Passage Reach VII in
Side Channel 21, October 15, 1984........e......0.e0.a0 D-62
Streambed profile of Passage Reach VIII in
Side Channel 21, October 15, 1984..........e....aP..e.g D-64
Streambed profile of Passage Reach IX in Side
Channel 21, October 15, 1984 ........................... D-66
Streambed profile of Passage Reach I in
Slough 21, October 15, 1984.. ...................Q...... 0-67
Streambed profile of Passage Reach I1 in
Slough 21, October 15, 1984 ....e.......e............... D-68
Streambed profile of Passage Reach IIIR in
Slough 21, October 15, 1384.. .......................... D-70
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1 INTRODUCTION
1, ; Background
Prel imi nary Pie1 d studies of passage conditions for adul t chum salmorl
keta) in selected slough and side channel spawning habiem
tats of the middle reach sf the Susitna River were cc3nductej
during the 1982 (ADF&G 1983: Appendix B) and 1983 (Sautner et 21, 1984
open-water field seasons. These studies evaluated the influence cf
selected channel geometry and hydraulic characteristics on chum salmon
passage into and within these habitats. The 1982 and 1983 repor-ts
provided the basis for identifying locations presenting potentis1
passage problems for salmon within slough and side channel habitats and
for establ ishing interim salmon passage criteria (criteria curves) for
estimating the mainstem discharges and local slough and side channel
flows required to provide successful and unsuccessful passage conditions
for adult chum salmon migrating into and within these habitats.
This addendum revises and supplements salmon passage data previous? y
reported in Sautner et al. (1984) and presents the results of the 1984
Passage Val idation Studies (PVS). The 1984 PVS was undertaken to verify
and/or refine the interim salmon passage criterl'a and flew requirements
previously established in Sautner et al. (1984). The initial salmon
passage criteria curves presented in Sautner et al. 1984) were based on
a review of limited salmon passage field data and observations collected
during 1982 and 1983 combined with the professional judgement cf project
Geographic location of passage study sites in
slough and side channel habitats of the
middle Susitna River, Alaska, 1984.
fisheries biologists and hydraul ic engineers. Due to the 1 imitetl f iei d
data available for the development of these curves, i"cwas necessary to
obtain additional field data in 1984 to validate the 1983 salmon passage
criteria. As indicated by the additional data and analyses from the
1984 PVS, the criteria curves from Sautner et a1 . 1984) were refined to
more closely represent natural passage conditions for churn salmon in
this report .
It was also necessary to refine the local flow analysis presented in
Sauener et a%, 1984). This analysis is primarily based on flow
estimates derived from limited cross section data and associated rating
curves, interpretation of aerial photography, and at some sites, from
observations by field personnel. Because of these 1 irni tations , only 38
of 74 passage reaches col~ld be evaluated for the initial local flow
analysis. In addition, the accuracy of the estimates developed was
questionable, as only 1 imited flow measurements were available for
compari son and val idation. For these reasons, additional cross sect ion
and local flaw data were collected during the 1984 PVS to provide a more
complete data base to evaluate local flow requirements at a17 currently
identified passage problem areas.
To more adequately assess the effects of mainstem discharge and local
flows on salmon passage conditions in slough and side channel habitats
in 1984 it was also necessary to further evaluate the relationship
between these two water sources. The available hydrologic data bases of
Susitna River habitats were used to evaluate the relationship bet~een
mainstem discharges and local flows within these habitats. This
information will provide more reliable local flow data for evaluating
passage conditions for the local flow analyses.
1.2 Objectives
To address the deficient areas in the previous salmon passage analyses,
the PVS was initiated during the 1984 open water field season to pursue
the fallowing field objectives:
1) Collect physical (hydraulic and substrate) 2nd bioiogjcal
(salmon passage) data at various slough and side channel
habitats in the middle Susitna River to btermine if the
previously establ ished salmon passage criteria curves (Sautner
et al. 1984) are valid or required revisions; and,
2) Collect additional cross section and local flow data to expand
and refine the local flow analysis presented in Sautner et al.
(1984).
Preliminary results of the 1984 PVS were initially presented in a
November 30, 1984 draft technical memorandum from A. Binyham to J.
Ferguson. Based on these results, the fol lowing objectives were
addressed in this addendum to supplement the salmon passage analyses
presented in Sautner et al. (1984):
1) Refine the 1983 passage criteria curves (Sautner et al. ::I841
which were developed from data collected during 1982 and 1983
and professional judgement;
2) Revise previously establ ished mainstem discharge and local
Plow requirements for successful and unsuccessful chum salmon
passage bared on revisions to the 1983 passage criteria
curves o,
Evaluate a1 9 new passage reaches establ ished during the 1984
PVS to determine mainstem discharges and local flows required
for successful and unsuccessful passage conditions;
4) Refine and expand the local flow analysis using additional
cross section and local flow data collected during the 1984
PVS; and,
5) Evaluate the presently available hydrologic data bases cf the
middle Susitna River to evaluate the relationship between
mainstem discharges and local flows at selected slough and
side channel habitats.
2,1 Site Selection
Salmon passage conditions were evaluated at 13 slough and side channel
sites in the middle reach of the Susitna Rfver (Table 1 With the
exception of Side Channel 10, these sites represent the major slough and
side channel spawning locations for chum salmon in the Susitna River
drainage upstream of Talkeetna. Sloughs 8A, 9, 9A, 11 and 21 are
primary spawning areas for chum salmon while the remaining sites support
lesser concentrations of spawning chum salmon. Although Side Channel 10
has not been utilized by spawning chum salmon in the past, it was
selected for study because of its potential as a mitigation evaluation
site. Discharge related passage problems have been previously identi -
fied at all the study sites (Sautner et al. 1984) with the exception of
Slough 19. Slough 19 was included as a study site because spawning chum
salmon had previously been observed at this site (Barrett et al. 1984
and no previous passage evaluations had been conducted.
22 Field Methods
2.2.1 Determination of Salmon Passaqe Criteria
Data from field observations of migrating chum salmon were col lected
within passage reaches at various slough and side channel habitats to
establ i sh minimum passage requirements (lengths and depths) necessary tc
provide successful and unsuccessful salmon passage conditions. Fish
Table 1. Summary of passage study sites and corresponding river miles
in the middle Susitna River.
Study Site River Mile
Whiskers Creek Slough 101,2
Mainstem 2 Side Channel $14,4
Slough 8A P25,3
Slough 9 128,3
Slough 9A $33,2
Side Channel 10 U3,8
Slough 11 1$35,3
Upper Side Channel 11 136,E
Slough 19 fl E40,O
Slough 20 140.1
Side Channel 21 140,6
Slough 21 141,8
Slough 22 %44,2
passage observations primarily focused on chum salmon due to their more
restrictive passage requirements and because they are the major salmon
species presently utilizing slough and side channel habitats in the
rrir"dd"%e Susi tna River,
Three conditians were defined to classify the relative degree of
diff icul ty encountered by salmon: 1) success"ful passage, 2 suc~e%sfu~
passage with difficulty and exposure, and 3) unsuccessful passage. Fish
passage cbservations were subjectively rankecf into one of these three
categories based on the characteristics out1 i ned be1 ow.
: Fish passage into and/or within a spawning
area is uninhibited. Characteriseics of this category are:
1) exposure of the fish above water is negligible; and,
2) uninterrupted movement of the fish passing through a reach.
Successful passage conditions would not adversely affect natural
production of salmon upstream of the area.
: Fish passage into
and/or within a spawninp 3rea is accomplished, but with stress and
exposure to predation. Characteri sti cs of thi s category are:
1) exposure of the dorsal surface of the fish above water;
one or more pauses by the fish e.g,, stranding, chjnging
directions, or resting within a passage re2ch due to shallow
water conditions; or,
3) repeated attempts by the fish to navigate a passage reach
before succeeding.
This condition of passage may potentially reduce the level of
st~ccessful spawning in the area and, over a long period of time,
may resdl t in a decline in natural production upstream of the area.
: Fish passage into and/or within a spawning
area may be accomplished by a 1 imited number of fish which, because
of excessive exposure, are more susceptible to increased stress and
predation. Character? stics of this category are:
1) absence of fish above a passage reach;
2) evposure of the dorsal surface of the fish above water
including partial exposure of eyes, gills, lateral Sine or
caudal fin;
3) one or more pauses by the fish within a passage reach result-
ing in unsuccessful navigation; or,
4 death of the fish while attempting navigation of a passage
reach,
Unsuccessful passage conditions may eventual 1 y el inli nate or great'\ y
reduce the natural production upstream of the area.
These tield passage data were later used to develop the salmon passage
cri$eria as described in Section 2.3,1.
2,2.2 Identification of Passase Reaches
Locations where potential salmon passage problems ex! st due to restric-
tions imposed by the physical habitat ( e depths, velocities
referred to as passage reaches. A passage reach is defined as a portion
of the channel at the mouth of or within a study site which fs
potentially limiting to salmon migration into spawning areas.
Passage reaches were initially identified in the field by locating areas
where water depth was potentially limiting passage of adult chum salman.
At each identified passage reach a transect was establ ished perpen-
dicular to the flow of water to represent the depth characteristics of
the passage reach and provide a consistent point of measurement.
Representative transects were es tab1 i shed at the shal lowest or most
critical point of the passage reach and marked with wood stakes and
rebar headpins. The physical habitat characteristics of individual
passage reaches were defined by measuring lengths, widths, and water
depths using the established transect as a reference point. The
criteria used to establish passage reach lengths, widths, and depths are
presented below.
P : The lo,igitudinal distance of a passage r.:nch
along the thalweg channel defined by the upstream and do~nstr-earn
points at which water depth is no longer limiting to salmon passage.
The length limits were defined at thalweg water depths of 0.50 feet
and 0.67 feet which correspond to threshold passage depths presented
in passage Criteria Curves I and II, respectively Sautner et a"].
: The distance from left water's edge
right water's edge (RWE) of a passage reach transect.
: The depth of water within a passage reach
which a Fish must navigate through in order to proceed upstream. In
the field, thalweg depth (maximun depth) was measured as an indica-
tor of the water depth affecting passage. The point of thalweg
tlepth at a passage reach transect was marked with a flagged spike or
a staff gage for a consistent point of measurelrent. However,
for analytical purposes it has been determl'ned that the thalweg
depth was not a representative variable of passage conditions. For
this reason, passage depth, defined as an average of the mean depth
and thalweg' depth at a passage reach transect, was used for
analytical purposes. As a result, thalweg depth measurements were
converted to passage depths during the data analysis using cross
section survey data (see Section 2.3.1) and were used in all
subsequent passage analyses.
Cr-iteria Curve II was eliminated following an analysis of the data
and all passage reach lengths previously defined in the field by
the 0.67 foot depth were redefined from thalweg profiles using the
0.5 foot depth see Section 2.3J
I 19
Passage reach lengths and widths were measured with a fiberglass survey-
or's tape graduated in one-tenlh fool increments. A standard surveying
rod or staff gage was used to measure the tl-lalweg depth at each
transect. Passage reach length, width, and depth measurements were
collected at the same time observations of fish passage were made.
Selected physical habitat data were collected to aid in evaluating the
effects of mainstem discharge and local flow on passage reach conditions
at slough and side channel study sites. Habitat data csllected included
survey data for development of thalweg and cross section profiles,
substrate and channel morphology data, and stage and flow measurements.
Detailed procedures used in the collection of these data are presented
in ADF&G (1983a), Quane et al. (1984), and Sautner et al. (1984).
Thaiweg surveys had been completed during the 1982 and 1983 field
seasons at all passage study sites except Slough 19. Therefore, survey
data for the development of a thalweg profile were collected at Slocl~h
19 to complete the set of thalweg profiles for all study sites. The
Slough 19 thalweg data were surveyed to a temporary bench mark (TBM) and
included additional data points at passage reaches to better define
these areas,
C 25s section profile data had been sporadically collected at pzssage
reaches during able 1981, 1982 and 1983 field seasons. A primary objec-
tive of the 1984 PVS was to obtain cross section profiles at as many
study sites as possible. Cross sections were surveyed at passage reach
transects which were typically located at the shal lowest cr most
critical point of the passage reach. These data were collec-ted to
provide an accurate representation of the channel marphol ogy present at
each passage reach. Included in the cross section surveys were
measurements of the streambed and water surface elevations at the
upstream and downstream 1 imits of a passage reach.
Substrate conditions at each passage reach were evaluated to charace*
terize the influence of substrate and channel configuration on salmorl
passage conditions. Substrate data were collected by visual ly c? assi -
fying the substrate present in the passage reach into the two dominant
size grgups based on the substrate size classification system presented
-in Tabk e2,
The channel configuration of each passage reach war a1 so subjectively
ranked as either a uniform or a non-uniform channel. A unlfom passage
reach was characterized by a relatively straight, unbraided channel that
concentrated the flow of water through one main channel. In coiYtrasl, a
non-uniform passage reach was characterized by a braided, irregular
channel that dispersed the flow of water over a wide area.
Stage and flaw data were collected during the 1982 and 1983 open water
field seasons. Addit~onal stage and flow data were collected at
Table 2, Substrate size classification system used for the 1984 Passape
Validation Studies,
Substrate Type Symbol Sg"me Class
SILT
SAND
very Pi nes
fi nes
SMALL GRAVE& SG 1/4-1'"
LARGE GRAVEL EG 1.-3"
RUBBLE RU 3-5"
COBBLE CO 5-10'"
B014LDER BO > loft
w
selected study sites during the 1984 field season to eompl imer:t these
data. Staff gages were utilized to obtain stage data at passage reaches
where backwater and/or breaching effects were not completely identified.
All mainstem discharge values related to these staff gages were
referenced from the USGS gaging station at Gold Creek USGS 1984 (gage
1115292000, KM 136.7)] unless othernise indicated. L.oca9 $9 CIW
measurements were col lected within slough and side channel si ter; using
either a Marsh-McBl roey electricai current meter or a Scienti f ie
Instruments Pygmy flow meter fol lowing techniques described in ADF&G
(1983a).
The analytical approach for evaluating the physical conditions affeclfng
salmon pass'qge in sloughs and side channels involved two steps. The
first step involved the development of plots of passage criteria data
(passage depth versus passage reach leng+;h) to describe successful and
unsuccessful passage conditions at passage reaches. Plots were
constructed for unifam passage reaches, non-uniform passage reaches,
and all passage reaches combined. The second step involved a comparison
of these passage criteria plots to the previously developed passage
criteria curves presentti fn Sautner et a]. 1984) to determine if
revisions ro the previous passage criteria were required to more
accurate1 y represent natural passage condi tions.
PI-ior to development of the passage criteria p'lots, the thalwey. dep-th
data required adjustments in order to be comparable to the 1902-1983
passage criteria. ihalweg depth measurements col Iected in the fie1 d
were converted to passage depth which is considered to be a more
accurate indicator of the water depth affecting salmon passage. Passage
depth is defined as an average of the mean depth and the thalweg depth
of a passage reach transect.
A relationship between thalweg and passage depth was developed using
linear regression techniques. The surveyed cross section data were used
to evaluate the mean depth corresponding to a specified thaiweg depth.
The mean and thalwey depths were averaged to obtain the passage depth.
Thalweg depths were selected to range from 0.1 to 1.0 feet to represent
a typical range of conditions at passage reaches. Passage reaches
within Sloughs 8A, 9, 9A, 11 and 21, Upper Side Channel 11 and Slough 21
were used in the analysis. Cross sections where multiple channels
existed (e. g. braided channel s) were excluded due to tjlei r
non-uniformi ty resulting in varying water surface elevations wi"chin the
cross section,
The following equation was derived, based on the above data, to estimate
passage depths (d ) from thalweg depths (d ). The relationship has a P t
correlation coefficient (r) equal to .995.
dp = 0.75 dt '*02 where d = Passage Depth and P
dt = Thalweg Depth
An adjustl~ent was also required For a portion of the passage 'ie~~gth iiita
col lected in the field. Initial ly, passage reach lengths were measured
based on thalweg water depth limits of 0.50 feet and 0.67 feet which
correspond to threshold passage depths presented in Criteria Curves I
and II, respectively (Sautner et al. 1984). However, during the 1984
fie1 d season it became apparent that passage reach length measurements
using the Criteria Curve iI thalweg water depth limit of 0.61 feet
included areas which did not present passage problems to migrating
salmon. Field observations during 1984 indicated that a thalweg k~ater
depth of 0.50 feet was a more appropriate upper limit. Subsequent
analysis of the data also supported the elimination of 0.67 feet as a
thalweg water depth limit in the passage analysis. Therefore, those
lengths measured using a thalweg water depth limit of 0.67 feet were
adjusted to represent lengths established by using a thalweg water depth
of 0.50 feet. This was accomplished by drawing a scaled diagram of each
affected passage reach including appropriate streambed and water surface
elevations based an thalweg and cross section survey data. A new
passage reach length was then measured directly from each diagram using
an upstream and downstream thalweg water depth limit of 0.50 feet.
iol lowing the appropriate adjustm3nts to passage length and depth
values, al: data points ere plotted by categories of fish passage
(successful , successful with difficulty and exposure and unsuccessful ) .
Three plots of the passage data were developed depicting 1
col lected at uniform passage reaches, 2) data collected at gon-uniform
passage reaches, and 3) all data combined.
.- -
1/12 original criteria curves were then superimposed on these paisage
eri teria plots to eval laate the accuracy of these previously establ i siled
curves by comparing the distribution of the passage data in relation to
the crl'teria curves. Based on the results of these con:parisons,
appropriate revisions were made to the passage criteria to better
represent the relationship between passage reach length and passage
depth.
2,3,2 Bassaae Reach Eva1 uations
This study util izes the same basic analytical approach for evaluating
passage conditions in the middle Susitna River as was presented in
Sautner et ale (1984). This conceptual approach is based on a procedure
involving three steps.
1) Defini-tion of the salmon passage criteria (water depth and
reach length) required for successful and unsuccessful salmon
passage (The analytical methods utilized to complete this step
are presented in the preceding section, 2.3,1.).
2) Identification of all the passage reaches within the selected
study sites which do not provide successful passage conditions
for migrating salmon under ail flow conditions based upon the
passage criteria established in step one.
3 Evaluation of each passage reach in terms of its hydr;:i~'i 4c:
characteristics, and determination of mainstem di scibarges
and/or 1 ocal f7 ows requi red to provide successful passage
conditions as d6:fined in step one,
The final step consists of three hydraulic analyses: a breaching
analysis, a backwater analysis, and a local flow analysis. The first
two of these analyses evaluate the independent effects of mainstem
breaching and backwater on passage conditions at passage reaches. The
third analysis evaluates the independent effects of local flow on
passage conditions at selected passage reaches only. The combined
effect of two or more of these conditions acting together was not
evaluated; the relative influence of one condition on another is quite
smal I,
In each of the three analyses, length and deptl. of passage reaches were
used as the primary criter+ia to evaluate salmon passage conditions. The
discharge and/or flow requirements resulting from each afialysis are
defined for conditions that fulfill threshold passage conditions for
successful and unsuccessful passage. By defining there upper and lower
boundaries, the middle condition of "successful with diff icul ty and
exposure" is also defined.
A flow duration curve [presented in Savtner et al. (1984)] was developed
for the period from .Sugust 20 to September 20 based on iqainstem
discharge data collected at Gold Creek over a 35 year period (USGS gage
'15292000), This curve was used to evaluate the percentage of tim? that
the discharge requirements for passage reaches are equalled or exceeded.
The mainstem discharge data collected at Gold Creek were also used to
evaluate the number of years that the discharge requirements for passage
reaches were equalled or exceeded for at least one day during the study
peri od.
2.3.2.9 Verification of Passaqe Reaches
Passage reaches were initially identified in this study from field
observdtians made during the 1984 open water seasan (see Section 2.1.2)
using salmon passage criteria previously established in Sautner et al.
(1984). As a result, it was qecessary to reevaluate the passage reaches
initially identified in the fl'eld based on the revised 1984 passage
criteria thresholds Lo determine if they still qualified as passage
reaches under the new psssage criteria. The verification process
consisted of comparing the range of physical conditions observed at each
passage reach with the revised passage criteria thresholds. Passage
reaches which fell below the successful passage threshold for at least
one set of flow conditions were verified as passage reaches far further
analysis. Passage reaches which consistently fell above the successful
passage threshold for the observed range of physical condiligns were
el iminated From further consideration since this was an indication that
passage problems did not exist at these sites.
A1 1 passage reaches thus identified and verified were sequential ly
numbered in ascending order beginning at the downstream end of each
site. The upstream 1 imit of the identification procedure was defiiied as
the first passage reach beyond the upstream limit of utiiiza"Lion by
spawni ng sal mon.
The breaching analysis in this study follows the same methods that were
presented in Sautner et al. (1984). Since breaching affects all passage
reaches within a site, the breaching analysis for each site is
appl icable to the entire study site. Initial breaching and control 1 ing
discharge values have been previously determined for each slough and
side channel study site with the exception of Slough 9A (Quane et ale
1984; Sautner et al. 1984). Estimates of the initial breaching and
control 1 i ng discharge values for Slough 9A were determined f ran stage
data, aerial photos and field observations. Passage reach conditions
are considered to be successful under control 1 ing discharge condi tians.
2.3.2.3 Backwater Analysis
The backwater analysis utilized in this study is conceptually similar to
the analysis presented in Sautner et al. (1984) with the erception that
specific steps involved in the analysis were modified to fit the revised
passage criteria. This analysis evaluates the influence that mainsten1
backwater has on passage conditions at passage reaches located in or
near the mouth area of each study site prior to breaching. As in the
1984 analysis, local flow was considered to be an insignificant factor
afiecti ng backwater relative to the effec"i sf unlainstem dfsci.iarg~ ind
was therefore not considered in the analysis.
Successful passage conditions are provided by backwa-ter at a passage
reach when the water sla~*l-l"ace elevatign sf the mainstem influenced
backwatei- submerges the highest point of elevation within a passage
reach by a water depth corresponding to successful passage over a
passage reach length of zero feet using the revised passage criteria.
Thus, the first part of the backwater analysis involved computing the
appropriate water surface elevations requi l%ed to provide successful and
unsuccessful passage conditions at each passage reac'.~ affected prior to
breaching. Mainstem discharges corresponding to these water surface
elevations were ca! culated from rating curve equations representing the
hydraulic relationships in the mouth areas of each study site. These
mainstem discharge values represent the minimum cli scharges required to
reet the threshold conditions for successful and unsuccessful passage.
The primary objective of the local flow analysis Nas to estimate the
amount and frequency of occurrence of the local flow which is required
to provide succr?ssi'ul or unsuccessful salmon passage condi tions at a
passage reach. The specific analysis followed is outlined below and is
depicted schematically in Figure 2.
----
ATER SURFACE
ELEVATIONS BJPSTREAM
AND DOWNSTREAM OF DISCHARGE
SECTION AND WATER
SU WFAiE ELEVATION
DATA APPENDIX A
APPENDIX A)
5. REQUIRED DEPTHS
FROM REVISED
PASSAGE CRITERIA
6. EVALUATE LOCAL
FLOW REQUIRED
FOR SUCCESSFUL
AND UNSUCCESSFUL
PASSAGE
7. LOCAL FLOW
FREQUENCY OF
OCCURRENCE
Schematic diagram of steps followed in the local flow analysis
at a passage reach,
1. Obtain a surveyed cross section and water surface elevi, ion
that are representative of the most di-Fficul t paisage
condimtion within a passage reach.
2. Determine the energy gradient at each passage reach which is
assumed equal to the steeper of the water surface slopes
upstream dnd downstream of the cross section.
3. Determine the local flow corresponding to the surveyed water
surface elevation at each passage reach.
4. Given passage reach substrate size and channel uniformity,
cal i brate Manning's equation to the surveyed water surface
elevation and to the corresponding local flow by selecting a
Manning's roughness coefficient from a range of accepatable
values.
5. Select the required passage depths from the given reach length
and the revised passage criteria for successful and
unsuccessful passage.
6. Determine the local flows corresqonding to the required
passage depths for successful arid unsuccessful passage using
the calibrated Manning's Equation.
7. Estimate the frequencies of occurrence of these loca flow2
which correspond to sirccessful and unsuccessful passage
condi"ons,
Cross section and water surface elevation survey data were col 1 ectec
fol 'lowing methods presented in Section 2.2.3, For assumed uniaform flow
conditions at passage reaches, the water surface slope is eclual Lo the
enei-gy gradient. The energy gradient was generally taken to be th?
steeper of the upstream and downstream water surface slopes. In cases
where the slope was not measured in the field, the wate.~ surface slole
was obtained from t!,alweg profile data.
Po provide estimates of the local flow corresponding to the surveyed
water surface eievdtion at a passage reach, local flow measurements vjert!
collected at selected study sites as described in Section 2.2.3. At
some passage taeaches, flow was measured concurrently with the water
surface el evatian measurements, At passage reaches lac~ing
corresponding flow measurements, a local flow distribution znalysis was
conducted to relate known flows at other passage reachss and ciischargt:
gages to the flow at trslese pasxagr? reaches. A detailed description of
this analysis is orovided in Appendix A.
Manning's Equation provides a re1 ation between required passage i:-pths
and local flows at the passage reaches. The equation was calibrated for
each passage reach where measured water surface eievaticn data wrrE
avai 1 able. At s'l tes where water surface elevations were riot obtained,
the equation was calibrated by comparison w:th equations From nearb-y and
Study S9 te
(River Mila)
e Reach
Passage d
Evaluation
Side Channel 10
[133,8)
Upper Side Channel 1%
(I36,l)
Slough 19
(140,O)
Unsuccessful
%uccessfu% /Di Cficult
Successful /Di f ficul t.
%uccessful /Di f fi cul t
Successful bBf f f icul t
Successful JDi f ficult
Successful JDi ff {cult
Uwsuccessful - -
Successful /Bi fficul t
Unsuccessful
Unsuccessful
Unsuccessful
Unsuccessful
Unsuccessful
Unsuccessful
Successful BDi ff icul t
Unsuccessful
Unsuccessful
Unsuccessful
Successful /Di ff ieuB&
Unsuccessful
Successful fDi Fdicuit
UnsuccessfuB
Successful dDi Bf icuB t
Unsuccessful
Unsuccessful
Unsuccessful
Unsuccessful
Unsuccessful
Successful /Di Ffi CUB t
Unsuccessful
Unsuccessful
Successful BBi df'icul t
Unsuccessful
Unsuccessful
Unsuccessful
h p.=' @ * -6.- 4-J U Cb, 63, &t? sW, g, a em sm f C fa 8" .D
A - -
m m
"a
@
4.J
Q
Q)
*r
"a3
6
.C
Q
L
pB -
E,
@
L
.@
BPB a
3
0
C
Dsll
Ca
FEl
we- -
Q
4J
*#==
423
VP
Q
(13
F
Bb8
C
(=1
a3
$I
0
4-J c rn
"6-
L
==a
C
Q
& 1 %
P--
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*#-
-=a
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42
a2
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psa
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ag
rlJ z
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9
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rn
ad.
Tabk 6* Sur~nary 0f mai nstsm dl schargss requi red to provi sfe successful ad unsuccessful sa l~iora passage c~ndi ti ons from baz.!(water
effects at selected study s4 tes in the middle SusPtna River,
-
Staff
Whi skess Creek SO sugh
(101 e2)
Met nstem 2 Side Channel
(144e4)
Slough 9A
(133.2)
Unsuccessful Successful Staf B
Side Channel 18
(%33,83
Upper Side Channel 1%
(136,l)
Slough 20
(14O,l8
Side Channel 21
(140,6)
Table 6 (Conti wued)
Side Channel 21 (continued) V%
g'940.6) vl a
VllB
B X
Slough 22 .
6144,3)
" This analysis assumes that local flows are negligible.
Passage reaches laeated in left and right channels of sites (facing upstream) are indicated as "L" and "R"', respectively.
e Percentage of total time for a 35 year flow record, that the indicated discharge is equalled or exceeded during the period
20 August - 20 September (USCS gage at Cold Creek, gage #15292000).
Percentage of total years for a 35 year flow record that the indicated discharge is equalled or exceeded during the period
20 August - 20 September (USCS gage at Cold Creek, gage t15292000).
" influence of backwater was not eva%ua$ed since breaching occurs at discharges lower than those required for providing baekwaeer
influence.
spabgn-ing period. The percent of total time values were taken Prori the
flew duration curve, whereas, the percent of years frequency values
indicate the relative number of years that the mean daily flow exceeded
the indicated flow for at least one day during the leriod.
The exceedence frequency based on time reflects the length of time in an
average year that the indicated Plow is equalled or exceeded. For
example, since the period of August 20 to September 20 contains 32 days
including start and end dales), then an exceedence frequency of 50
percent, :vhich corresponds to a discharge of 15,000 cfs, would indicate
that in an average year, 16 days (50 percent of 32 days wou'l d have
daily discharges equal to or in excess of 15,000 cfs. The daily
mainstem discharge exceedence curves for ID%, 50% and 90% of the time
are presented in Figure 9.
The exceedence frequency based on years reflects the number of years
that the indicated flow is equalled or exceeded for at least one day
during the study period. For the example above using 15,000 cfs, the
exceedence frequency bared on years is 97 percent. That is, 34 of 35
years had at least one day during the study period with a mean daily
discharge equal to or greater than 15,000 cfs.
3,2,2
Estimates sf local flow corresponding to successful and unsuccessful
passage conditions at selected passage reaches within study sites are
MAINSTEM DISCHARGE THKr
WOULD BE EXCEEDED:
---- 50°/o OF %WE TIME
90% OF THE TIME
0
SEPTEMBER
Figure 3. Daily mainstem discharge exceedence curves for the August 20
to September 20 salmon spawning period in the middle Susitna
River. Exceedence curves were developed from 35 years of SSGS
9 P?3#%11APIh 3 dischar~e daeci ex Go1 d Creek (Stztion NG. ~3~3~u\rij u3
wthods described in Chapman
provided in Table 7. These estimates provide an indication of the
quantity of local flow required for passage in the absence of the direct
effects of mainstem influenced backwater and breaching.
Exceedence frequencies are provided at those sites For which a relation-
skip between mainstem discharge and groundwater contributions to 1 ocal
flow can be established. Local flow in sloughs and side channels is
compri sed mainly of groundwater upwe1 1 i ng driven largely by mainstem
water levels and runoff from precipitation events. The exceedence
values reflect the percent of time that the passage condition is met or
exceeded during the period from August 20 to September 20 as a result of
precipitation events that generate local flows sufficient to supplement
groundwater upwel l i ng flow corresponding to a median ma7 nstem discharge
of 15,000 cfs for the period.
Since precipitation records r'l lustrate that precipitation in any amount
falls only half of the time during this period, exceedence values range
from 0 to 50 percent. A 0 percent frequency means that the amount of
preci pi tat ion requi red to produce 1 ocal f 1 ow to svppl emelat groundwater
generated flow corresponding to a median mainstem Plow for the period is
so large that it occurs very infrequently e.g. 1 in 10 years
i ntermedi ate exceedence frequency such as 22 percent indicates that the
combination of groundwater generated f l ow correspond< ng to a mai nstem
discharge of 15,000 cfs and runoff from a precipitation event which is
equalled or exceeded 22 percent of the time is sufficient to provide the
required passage flow. An exceedence of 50 percent or greater indicates
Table 7. Summary of local $1 QWS requO red for successful and unsesceesst:ul passage eondi $ions and the frequencies of accksrrence based
on precipitation and groundwater contributions at an average Susitna River di schsrge of 95,880 cfs during the August 20 $0
September 20 per i od,
Study Site
(Rivet Mile)
Length Depth Fl ow Percent Depth FB ow Percent
Number Q ft) gftl (cfs) Exceedence (ft) (ef s) Exceedence
Mhi skers Creek
(401,2)
Slough 8A
{925,9)
Slough $A
(133,6)
Pas
Length Depth Fl sn Percent Depth Fl ow Percent
Number (ft) (ft 1 gcfs) Exceedenca (fe) [cfs] Exceedence
Study SB te
[River Mile)
Slough I 1
(135,33
Upper Si de Channel 99
(136.1)
Side Channel 21
g lSO,f,)
*a -
Tab1 e 7 (Continued) ,
Study Site
(River Mi le)
Conditions
f
Length FI ow Percent FI obtr Percent
Number (fe) (ft) (c~J) Exceedence t(ft) (c f~,) Exceedence
Slough 21
(141 -8)
a Frequenci es not evaluated.
No cross section data available.
that the flow resulting from groundwater upwelling at a median mairstem
discharge of 15,000 cfs is sufficient to provide the required flow for
passage without precipitation input. The mainstem discharge and
associated frequency that would be required for successful and unsuccess-
ful passage conditions at passage reaches in Sloughs 8A, 9, and II in
the absence of any precipitation input is given in Table 8.
Table 8, Frequencies of occurrence of local flows evaluated thrsugh the case of mainstem versus local flow relationsiaripg in Sj~ughs
88, 9 and 11 ex~tuding the effects of breaching and backwater,
Requdred Local Flow Requi red Mai nstem Discharge Frequency of Occurrence
Passage Qcfs) (cfs)
Reach So~ccessf ul Unsuccessful Successful Unsuccessful Successful Unsuccessful
Slough 9
~ 443 DISCUSSION
The analysis of the salmon passage data collected during the 1984 open
water season resulted in revisions of the passage criteria curves
developed from the 1982 and 1983 passage data Sautner et a%. B984
The final product of the analysis was the development of a single set of
salmon passage criteria thresh01 ds for establ i shing successfu1 and
unsuccessful salmon passage conditions In general, the same
assumptions corresponding to the original criteria curves in Sautner et
1984) are appl icable to the revised passage criteria thresholds.
However, based on field observations of salmon passage, one of the
important assumptions regarding the passage criteria requi red modif ica-
tion. This assumption was originally stated as follows:
1. All passage reaches can be described as either uniform,
straight channels with small substrate (less than or equal to
3 inches in diameter), or non-uniform braided channels with
1 arge substrate greater than 3 inches in diameter).
Exceptions to this assumpti on were encountered at several passage
reaches (e.g. Sloughs 20 and 21 during the past field season. Non-
uniform channels were observed at passage reaches with predominant1 y
small substrate, and passage reaches with predominantly large substrate
and uni.form channel s were a% so encountered In these sit-
uations it was often very difficult to classify certain passage reaches
unde~ one of the original criteria curves. This required Cha' the
re1 a"cive .importance of channel configuration and substrate si ie be
reevaf uated. Based on field observations, differences in channel
configuration appeared to have a greater overall influence on flow, and
therefore c6 salmon passage conditions, than substrate size. Therefore,
if substrate is disregarded as a factor in the salmon passage criteria
analysis, the above assumption can be rewritten as follows:
1. A passage reaches can be described as either uniform,
straight channel s, or as non-uniform, braided channel 5.
This assumption indicates that passage reaches can still be classified
into two categories which would theoretical ly requi re two separate sets
of criteria curves as in Sautner et al, However, when length
and depth data for both uniform and non-uniform passage reaches were
plotted separately and together, there was no distinct evidence to
indicate the requirement of two sets of criteria curves. The combined
passage data (col lected from both gniform and non-uniform channel s)
closely fit Criteria Curve I for unifon channel s, whereas Criteria
Curve I I, for non-unifom channel s, overestimates water depths required
for successful passage. This was verified in the field when measuring
lengths of passage reaches using the Criteria Curve II thalweg water
depth @>f 0.67 feet. Passage reaches for which this depth value was used
for establishing the upstream and downstream limits included water
depths where fish did not appear to have any passage problems. A
thalweg water depth of approximately 0.50 feet, which corresponds to
6.-l'teria Curve I, appeared to be a more accurate .indica"cor of the depth
of water at which salmon first encounter passage difficulty.
Based on these reasons, and supported with field observations, it was
determined that only a single set of passage criteria thresholds is
necessary to accurate1 y describe natural salmon passage corldi ti ons.
Hence, the previous assumption was modified to read as fallows:
I. All passage reaches influence salmon passage conditions in a
similar manner regardless of channel conf iguratian and sub-
strate size,
The salmon passage criteria threshol ds developed in this addendum are
sirnilart to Criteria Curve I from Sautner et al. 1984) with some modi-
fications based on the 1984 data. The most significant modification to
the passage criteria involved the 0-20 feet range of the curves for both
successful and unsuccessful passage. When the original criteria curves
were developed in 1984, the sharp downward inflections in this range of
the critera'a curves were assumed to refkd ta nintuitive idea that
salmon are able to swim through very shallow depths for short lengths.
Thi s adaptatjon was based solely on intuition and the professional
judgement of several project personnel with various backgrounds.
However, the salmon passage data collected during the 1984 field season
were not sufficient to support the sharp, downward inflections in the
8-20 feet range of the original curves. Genera1 field observations of
chum salmon passage also did not support this adaptation in the original
curves (Blakely pers. comm, 1984 In addition, very few passage
reaciles identaified during the 1984 Field season had passage% reaci.1
lengths that fit into the 0-20 feet range of the passage cfiteria.
Thus, the original criteria curves were modified to reflect these field
observations and additional data, resulting in the development of two
straight lines, referred to as salmon passage criteria thresholds, which
more accurate1 y reflect salmon passage conditions.
The assumption that salmon are able to swim through shallower depths at
shorter reach lengths may be falsely based on the well known ability of
salmon ta leap over obstacles such as waterfalls. However this ability
is only characteristic with the physical and hydraul ic features present
at waterfa1 I s eg. , plunge pool depths, water velocities
conditions are not characteristic of passage reaches in sloughs and side
channels of the middle Susitna River and thus there were no observations
of salmon "jumping" over passage reaches of shorter reach lengths.
The salmon passage criteria thresh01 ds developed in this addendum are
represented by two straight lines which best fit the salmon passage data
collected during 1984. Placement of the threshold lines for successful
and unsuccessful salmon passage indicates that passage depth appears to
be the critical physical factor affecting passage conditions. Passage
reach length is not as critical in relation since passage depth
increases only 0.05 feet over lengths up to 200 feet.
During the 1984 open water field season, 85 passage reaches were iden-
tified at selected slough and side channel study sites of the middle
Susi tna River compared to 74 passage reaches previously identified in
Sautner et al, . The difference in the number of passage reaches
is primarily -2llated to the specific methods employed to identify
passage reaches. In Sautner et al. passage reaches were
identified strictly from surveyed thalweg profiles of each study site.
However, the majority of these thalwegs were not surveyed for the
purposes of analyzing salmon passage conditions. Thus, certain passage
reaches within some study sites were not adequately defined on the
thalweg profiles. In contrast, identification of passage reaches during
the 1984 PVS were based on actual field observations. This method
resulted in the identification of new passage reaches, the elimination
of some previously identified passage reaches, and in some cases, the
division of a single, previously identified passage reach into two
separate passage reacnes. In addition, Slough 19 was included as an
additional study site to be evaluated for passage. Therefore, the
methods employed in this addendum result in a more accurate and complete
identification of passage reaches compared to the methods utilized in
Sautner et al.
Mainstem discharge estimates resul Ling from the backwater and breaching
analyses were also presented as percent exceedence frequencies based on
time and years. Although these percent exceedence values are supposed
to represent the enti re period of interest, they may contain an *; sherent
bias towards the first two weeks of the August 20 to September 20 salmon
spawning period. An evaluation of the daily mainstem discharge
exceedence curves for 10%, 50% and 90% of the time
that the middle Susitna River discharge general ly decreases th+ough the
period of interest, It is also apparent that higher discharges occur
with greater frequency during the first half of the period of interest.
Discharges generally decrease in the latter half of this period. The
decreasing trend in mainstem discharge val ueo is general 1 y consistent
during the entire period with few periodic spikes or peaks. Although
the percent exceedence values presented in this addendum are for the
entire August 20 to September 20 period, these values are more indi-
cative of the first half of the salmon spawning period rather than the
last half because this is the period when the higher discharges can be
expected to be equal 1 ed or exceeded.
The mainstem Susi tna River directly influences salmon passage conditions
within a slough or side channel when the head of a site becomes
breached. This event is significant since after mainstem breaching has
occurred all the passage reaches within a site are affected in a similar
manner. The breaching analysis in this addendum provides a summary of
the mainstem discharges which are required to breach selected study
sites in the middle Susitna River. These results are essentially the
same values that were reported in Sautner et ale with the addim
tion of mainstem dhhaagge estimates for Sloughs 98 and 19. Al'hoiagh
two breaching discharges are presented for each study site, co~tvolling
di schai-ge values are of primary importance since fie1 d obsewalions have
shown that successful salmon passage conditibns exist at all passage
reaches within a site when control 1 i ng mai nstem breacki vlg has occurred.
Initial breaching discharges are only presented to provide an indication
of when a study site is initially overtopped by mainstem water and may
be considered to approximate the discharge representing the unsuccessful
thresh01 d value,
A review of the results of the breaching analysis i ndi cates
that the majority of study sites breach at relatively high mainstem
discharges 19,000 to 42,000 cfs). This includes Sloughs 8A, 9, 11 and
21 which comprise a major portion of the primary spawning areas far chum
salmon in the middle Susitna River. Under natural flow conditions,
these re1 ativel y high mainstem discharges 19,000 to 42,000 cfs
equalled or exceeded less than a third (29%-1z3 ,respective1
total time for the period August 20 to September 20 (Table
discharge values of 19,000 to 42,000 cfs also correspond to 77%-9%,
respectively, of the total number of years in which the breaching
discharge is equalled or exceeded at least once during the August 20 to
September 20 period. However, the exceedence frequencies for the total
number of years contains an inherent bias towards the first two weeks of
the perf od of interest.
In addition to breaching effects, the mainstem Susi tna River di reetly
affects salmon passage in the mouth area of a slough or side channel by
creating backwatei pool s. As mainstem discharge increases, the stage sf
the backwater pool progressively rises and inundates the 1 ower portion
of the site. This effect is important in regulating the passage of
salmon into a slough or side channel spawning site at mainstem dis-
charges less than those required for breaching.
The backwater analysis in this addendum presents a summary of the
mainstem discharges which provide successful salmon passage conditions
from backwater effects at selected study sites in the middle Susitna
River. It is evident from the results that, in general, only the
initial Few passage reaches located in the mouth regions of study sites
are inundated by backwater prior to breaching. However, at three sites
Whi ers Creek Slough, Upper Side Channel 11 and Slough 21
i nf 1 uence of backwater on passage condi tians is complete1 y absent prior
to breaching. In these cases, the effects of breachl'ng and local flow
become increasingly more critical in providing successful passage
csndi tions.
A comparison of the results of the backwater analysis in this addendum
to the results previously reported in Sautner et al. is presented
in Table 9, It is evident from the comparison that the mainstem dis-
charge values for successful passage conditions from both studies are in
Table 9& Cornpart son of the results sf the backwater' ansbsis presented - n this
addendum to the results previously reported in Sautner et a%, (1984%
for sloughs and side channels in the middf e Susitna River,
study S; t@
(River Mile)
u-: '%,cam
'-ha I t Id Br'brll. 2
Side Channel
(Ilap,b)
Slough 9
("E28,3)
Slough 9A
(133,2)
Side Channel 18
("933,)
Side Channel 25 I
(%40,6) I I
Slough 22
Q14&.3)
" This site not evaluated.
Breaching occurs at mainstem discharges lower than those required for providing
bac kwa tee i nf l uence,
yenera? agreement. The discharge values established in this adde !durn
cunstitute a general increase of less than 1,009 cfs over values rel~ort-
ed in Sautner et ale However in a few cases eg, , Passage Reach
I in Slough 8A values differ more than 1,000 cfs for successful
ijj.ssage. These larger differences are due to better defined ratin9
curves established during the 1984 Field season whl'ch provjde more
accurate estimates of mainstem discharge.
Overall, discrepancies between the mainstem discharge values reported in
both studies are a reflection of the revised passage criteria thresholds
and their application in the 'ackwater analysis. The methods which
comprise the backwater analysis include the determination of the depth
requirements for successful passage for a reach length of zero feel from
the revised passage criteria thresholds. In this addendum, a passage
depth of 0.32 feet corresponds to the zero reach length for suecess"i1
salmon passage. In Sautner et al. (1984 the comparative passage depth
froa Criteria Curve I was 0.26 l'eet. Although the difference in the
passage depth values is only 0.06 feet, it accounts for the general
increase in mainstem discharge values reported in this addendum. In
general, where discrepancies in the results of both studies occur, it
should be noted that the resdts of tkls addendum are refinemen"%s of
those reported earl ier and are therefore considered more re1 iable.
The local flow analysis has been refined and expanded cons?derably from
the analysis presented in Sautner et a7. (1984). The 1 imited data
available for the previous analysis resulted in a few ger,era1
assumptions. Data were collected during the 1984 op30 water season *to
eliml'nate most of these assumptions and allow a more thorough analys'is
of the local flow required for passage in sloughs and s*ide charnels.
The refined analysis necessitated detailed assumptions. In addition,
neither the groundwater distribution analysis nor the Iscd flow
frequency analysis were conducted for the passage evaluations presented
in Sautner et al. (1984). These additional analyses and refinement of
the methods used to evaluate local flows resulted in the following
additional assumptions which are more specific and expanded from the
assumptions presented in Sautner et al.
1. The surveyed cross section is representative of the most
difficult passage condition within the passage reach.
2. Local flow in passage reaches is composed of surface water
runoff and upwelling contributions from identified upwelling
sites and upwell ing distributed uniformly along the chapnet
bed,
3. The local flow distribution analysis evaluates flow at a
passage reach which is representative of field conditions.
/r -t d) The percent groundwater values are constant at a site for all
slough and mainstem flows.
5. The groundwater Flows can be represented by local flows
measured during a period of low rainfall.
6 Antecedent moisture conditions are invariable and have a
negl igjble effect on surface water runoff.
7. The August precipitation duration curve at ialkeetna is
applicable to the August 20 to September 20 salmon spawning
period.
8. Precipitation at Talkeetna may be adjusted to represent
rainfall conditions at sloughs and side channels of the middle
river by using precipitation coefficients.
9. Basin areas contributed surface water in accordance with
identified percent runoff factors. The factors are constant
for all ra%nfall amounts.
10. Manning's Equation is applicable to the low flow and shallow
depth conditions at passage reaches.
11. Manning's Equation can be calibrated at a known flow and
corresponding water surface elevation; the calibrated equation
may be applied to thalweg depths up to one foot.
12. Local flow in passage reaches is uni-form; for unifoimn flow,
the energy gradient is equal to the slope of the water sur-
face,
13. The flow characteristics at a passage reach are governed by
the maximum of the upstream and downstream water surface
slopes at the cross section.
14. Manning's roughness coefficients are uniformly greater at the
shallow depths associated with the passage analysis in compar-
ison to the flood flow roughness values found in the litera-
ture (Chow 1959).
15, Flow excluded by flow computations using surveyed cross
section data is a constant amount that is continuously under-
predicted at all depths,
Required local flow values for successful and unsuccessful salmon
passage conditions presented in this addendum are fairly similar to
previous values (Table 10). Variations between the addendum resul ts and
" previous values may be partially explained by variations in the
calibration of Manning's Equation. in Sautner et al.
Manning's roughness coefficient was used at all passage reaches. In the
addendum, a si te-specif ic Manning's roughness coefficient reflected
variations in passage reach substrate and channel uniformity. The
energy gradient was approximated in the previous study from the water
Tab'Sei10, Comparison of the results sf the local flow analysis presented ire this
addendum to the results previously reported in Sautner et a7 , ("a9849 far
sS~ugRs and sSde channels in the middle Susitwa River,
Local Flow befs)
Present Addendum SauQner et ale 49984)
Study Site Passage s-
(River Mile) Reach Unsuccessful Successful Unsuccessful Successful
mi skers Creek 59 sugh
("pL.2)
Mai nstem 2 Side Channel
(I 14,4)
Slough 1%
(aa3SB3)
Upper Side Channel 11
(136,l 1
Side Channel 29
(140,6)
surface gradient evaluated over large reaches on the tha'iweg I rofile,
In the addendum, the water surface gradient was predominant1 y abtrmi ned
from field measurements of the water surface upstream and downstream
from the cross-section. The cross-section database was much smaller
previously; cross-sections were often unavailable within passage reaches
and nearby cross-sections were used in the analysis, Cross-section data
col lected within passage reaches during the 1984 field season enlarged
the database and permitted a more thorough analysis of local flows
required for passage,
The two principal sources of local flow in sloughs and side channels of
the middle Susi tna River are surface water runoff and groundwater
upwell ing. These sources of local flow are influenced by mainstem
discharge and by precipitation events. Surface water runo-ff is a
function of precipitation and basin characteristics, and is not influ-
enced by fluctuations in mainstem discharge. Since precipitation in any
amount falls roughly half of the time during the spawning period,
surface runoff is generally periodic during this time. Most drainage
areas contributing to sloughs and side channels are quite small and
steep; thus surface runoff decreases substantial ly or stops soon after
the precipitation stops, As a result of the intermittent nature of the
surface runoff component of local flow, groundwater upwell ing plays a
major rol? in sustaining flok in sloughs and side channels during
unbreached periods.
Groundwater lapwe1 1 ing during the spawning period originates frorr any of
three sout-ces: 1 shallow localized infiltration from the mainstem; 2
local ized infiltration from precipitation events; and 4
groundwater transport in the down val ley direction AEIDC 1985). Of
these three sources, only the first is directly influenced by short term
fluctuations in mainstem stage. This localized source fluctuates daily
in response to daily fluctuations in mainstem stage. This direct
influence is demonstrated in a set sf linear regression equations that
re1 ate the apparent groundwater component of slough f 1 ow to ma1 nslem
stage or ma'l'nslem discharge e. g. , H-E 1984, Beaver 1984, R&M 1984
The most recent version of these equations, developed as a function of
mainstem stage (Gemper1 ine pers. comm. 1984 were used in the frequency
of occurrence; analysis presented in Appendix A. Such relations have
only been developed for Sloughs 8A, 9 and 11 and cannot be general iaed
for application to other sloughs and side channels. A relation has been
developed for Slough 21 but is not applicable at mainstem discharges in
the raqge considered in these passage analyses.
Another local ized and f 1 uctuating component of groundwater upwell ing is
that generated from precipitation events. This component general 1 y
enters from the valley wall side of the slough or side channel and is
not all causzlly related to mainstL discharges. This component of
groundwater upwell i ng is di rectly re1 ated to surface water runoff from
precipitation. However, the response of infil trat-ing precipitation
would be delayed in comparison with the rapid response of surface water
runoff. The influence of ths's source of groundwater upwelling has not
been quantified,
The regional groundwater transport component of groundwater upq,iell i ng
prov-ides the base flow in the slough or side channel. This compoi?en"t
may fluctuate slightly on a seasonal time scale, but would remain Fairly
constant during the spawning period. The amount of local flow provided
by this source depends ukon the length and characteristics of the slough
channel that intersects this source. Base flows in sloughs and side
channels have not been quantified as a separate entity, but are incor-
porated in the local flow values resulting from the regression equations
discussed above,
The mainstem discharge and local flow values presented in this addendum
differ in some cases with values previously reported in Sautner et ale
In general, where discrepancies between the results of boLh
studies occur, the results presented in this addendum are considered
more reliable since they are based on refinements of both field and
analytical methods.
The evaluation of salmon passage conditions presented in this report is
based on the present hydraulic and morphologic characteristics of slough
and side channel habitats. An important consideration that should be
examined in future application of these data relates to physical changes
that may occur within these habitats in the future. Changes in the
natural sediment load af the Suritna River may result in aggradation or
degradation of the streambed of sl.ough or side channel habitats. Ice
conditsions may a1 so result in changes in present channel rnorphoi ogy.
Any changes in the present channel morphology may ~esult in changes in
the mainstem discharge and local flow values required for salmon passage
as presented in this report. With these limitations in mind, the
fa1 1 cwi ng conclusions were derived from this study.
1. A1 l designated passage reaches influence salmon passage
conditions in a similar manner regardless of channel config-
uration and substrate size,
2. The passage criteria data indicate that two separate sets of
criteria curves are not required to describe passage require-
ments for chum salmon,
3. The thalweg depth threshold of .! ;*' feet from Criteria Curve
I1 is an overestimate of the water depth required for success-
ful passage for chum salmon. A thalweg depth of 0.5 feet is a
more accurate indicator of the depth at which salmon would
first encounter passage difficulty,
4. The revised salmon passage criteria are represented by two
straight lines, referred to as threshold limits, which best
fit the passage criteria data c~ilected during 1984. The
threshold 1 imi ts represent the criteria for successful and
unsuccessful passage of chum salmon in the middle reach of the
Susi tna River,
5 The distribution of fish passage field observa'cs'orts in
relation to the threshold 1 imits for successful and unsuccess-
ful passage of chum salmon support the revision of the origi-
nal eri Qeri a curves,
6. Field observations and passage data collected during 1984 do
not support the downward i nf 1 ecti on represented by the f i rst
20 feet of the' original criteria curves. Extensions of
straight 1 ine threshold criteria for reach lengths greater
than 20 feet continued through this 0 to 20 feet range in the
revised passage criteria threshold 1 imi ts.
7. Passage depth appears to be the critical physical factor
affecting salmon passage. Based on the threshold limits for
succesrful and unsuccessful passage of chum salmon, passage
depth increases only slightly over passage reach lengths up to
200 feet and is assumed constant for lengths greater than 20C
feet,
8. A total of 85 passage reaches were identified at selected
slough and side channel study sites of the middle Susitna
River based on field observations,
9. Breaching is important in providing successful passage con-
di tions, but only at relatively high mainstem discharges at
the majority of slough and side channel study sites in the
Middle Susltna River.
10. Backwater is a dominant factor in providing successful passage
conditions Prom the mainstem into some slough and side ciiannel
sites by inundating the lower most passage reaches -in each
si tea
11. Local flow is influenced largely by mainstem discharge levels
and by precipitation events.
12. Local flow is important 119 providing pertodic conditions for
successful passage and more frequent conditions for successful
passage with difficulty and exposure at those sites infre-
quently receiving direct mainstem influence through breaching
or backwater,
\o $7 -3-3 E 0 ca 323
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The authors express their appreciation :o the following For their
assistance in preparing this report.
- - The other staff of ADF&G Su Hydro Aquatic Studies Program who
provided their support to this report.
do) - E.W. Trihey, E.W. Trihey and Associates, and S. Bredthauer and
R. Butera, R&M Consultants for their consul tation regarding
various aspects of the hydrologic and hydraul ic data analysis.
9.0 LITERATQWE CITED
AEIDC. 195, Susi tiia River ice Processes: Natural c~ndi tion-; and
projected effects of hydroelectric development, draft report, Apri:
5, 2 \Jal.
Alaska Department of Fish and Game. l983a. Aauatic studies procedures
manual, Phase EI 1982-83). Subtask 7.10. Alaska Department of
Fish and 62 ~e Susitna Hydimo Aquatic Studies. Anchorage, Alaska.
Barrett, B.M,, F.M. Thompson, ai~d SeNo Wick, editors. 1984. Adult
anadromous fish investigations: May-October 1983. Alaska
Departaent of Frsh and Game Susitna Hydro Aquatic Studies. Report
No. 1. Prepared for Alaska Power Authority. h -e, Alaska.
Beav~r, D.W. 1984. Slough Discharge Regression Relations. Memo to
E.J. Gemperl ine, H-E, 12 October.
Blakely, J. 1984. Personal Communication, Alaskd Department of Fish
and Game. Susi tna Hydro Aquatic Studies. Anchorage, Alaska.
Chapman, D.L. 1982. Daily flow statistics of Alaskan streams.
National Oceanic aid Atmospheric Administration Technical
Memorandum NWS AR-35. National Weather Service. Inchorage,
Ahaska.
Gemperl i ne , E, 1984, Personal Csmmunicatisn, Waraa--Ebn:jscc,
Anchorage, A1 aska.
Marza-Ebasco (H-E) . 1984. Slough geohydrol ogy studies. Prepared for
Alaska Power Authari ty. Anchorage, Alaska.
R6M Consultants. 1384. Water balance studies of middle Susitna River
sloughs. Draft. Prepared for Harza-Ebasco. Anchorage, A1 aska.
Quane, T., P. Morrow, and T.W. Withrog. 1984. Chapter 1: Stage and
discharse investigations. In Report No. 3: Aquatic Habitat and
Instream Flow Investigations (May - October 1983), by C. Estes and
D. Vincent-Lang, eds. Anchorage, Alaska.
Sautner, J., L.J. Vining, and L.A. Rundquist. 1984. An evaluation of
passage conditions for adult salmon in sloughs and side channels of
the middle Susitna River. Chapter 6 in 1984 Report No. 3: Aquatic
Habitat and Instream Flow investig~tions (May-October 1983
Estes, C.C. and D.S. Vincent-Lang, eds. Alaska Department of Fish
and Game Susitna Hydro Aquatic Studies. Anchorage, Alaska.
U. S. Geological Survey (VSGS). 1984. Provisional summary of 1984 water
resources data for Alaska,
Appendix A. Supplement to Local Flow Methods
Appendix B. Passage Reach Distribution Maps
Appendix C. Thalweg Profiles of Passage Study Sites
A+pendix D. Cross Sectional Data
Appendix E. Stage and Discharge Data
APPENDIX A
Supplement to Local Flow Methods
APPENDIX A -----
The general procedure for evaluating the required amount of local flow
necesrav for successful. and unsuccessful passage and the frequency at
which these required flows are expected to occur is described in Section
2.3.2.4. This appendix presents detailed methods for evaluating local
flow disWribuLion within a site, calibrating Manning's Equatiol, and
evaluating the frequency of occurrence of local flows.
Local Flow Distribution Analysis
At passage reaches where discharge data were not collected, discharges
byere estimated from discharges measured el sewhere within the slough or
side channel. The general procedure used to estimate the discharge at a
passage reach involved assigning a percent groundwater flow value to
each passage reach relative to total flow at an R&M discharge gage or
other reference, suck as another passage reach. These percent ground-
water flow values were assumed to be constant at all slough and mainstem
flows. The discharge at a specified passage reach may be estimated by
b
multiplying the percent groundwater flow value at the passage reach by a
discharge measured elsewhere in the slough or side channel and adjusting
this discharge for tributary and surface water inflow.
The percent groundwater flow values at passage reaches are evaluated
through the use of aerial photographs, on-site investigations and
discharge data measured at slough gages and passage reaches. Ground-
water flow at a site is considered to be composed of both inflow e~~e~ly
di stri brited a1 ong the channel bed and inf 7 ow concentrated a"cppwe1 l i ng
sites j~isible in aerial photographs or 'located during site investi-
gations (R&M 1982). Appendix Figure A-l illustrates tk eoeneral pro-
cedure used to estimate the percent groundwater flow values. The
upwel l ing sites were assigned percent groundwater flow values from field
experience. At Sloughs 8A, 9, 11 and 21, the R&M discharge gage
location was designated the 100 percent groundwater flow value. At
sloughs and side channels lacking an R&M gage, the most downstream
passage reach Passage Reach I) was designated to be the reference point
far 100 percent groundwater flow. The percent groundwater flow value at
each passage reach was estimated by summing the percent groundwater flow
values from 1) upwelling sites upstream of the passage reach and
the channel bed groundwater contribution.
Discharge data available at various passage reaches on the same date or
on a date with a similar mainstem flow and antecedent precipitation were
util ized to verify or adjust the percent groundwater flow values, Local
flow data collected during the 1984 open water field season are
preseilted in Appendix E (Appendix Table E2). The R&M discharge gages
provided an additional source of discharge data for comparison of the
percent groundwater flow values. The evaluated percentage valu;s at the
passage reaches of the sloughs and side channels considered are
presented in Appendix Table A-1.
PHOTOGRAPHS AND FIELD INVESTIGATIONS
/ ASSIGN EST lMATED PERCENT GROUNDWATER
I INFLOW VALUES TO UPWELLING SB"$ES (Oie)
SUM "$HE @lo VALUES OF SITES UPSTREAM
FROM THE R?:M GAGE', X=ZO/e
--
EVALUATE CHANNEL BED GROUNDWATER
CONTRIBUTION AT R 8 N GAGE*, Y = IOO%-X
EVALUATE CHANNEL BED CONTRIBUTION FACTOR (Z)
Z = (YDlSPANCE FROM RBM GAGE* TO HEAD)
ESTIMATE PERCENT CONTRIBUTION FROM CHANNEL
BED AT EACH PASSAGE REACH (PI)
PI = (Z H DISTANCE FROM PASSAGE REACH TO HEAD)
SUM THE Ve VALUES OF UPWELLING S!TES
UPSTREAM OF EACH PASSAGE REACH (P,)
EVALUATE THE GROUNDWATER INFLOW AT
EACH PASSAGE REACH (PI + B2)
VERIFY OR ADJUST @I0 VALUES USING DISCHARGE DATA
' AT SLOUGHS AND SIDE CHANNELS WITHOUT R BtM GAGES,
PASSAGE REACH I WAS SUBSTITUTED FOR THE R@-M GAGE.
Appendix Figure A-1. Illustration of the general procedure used in
the local flow distribution analysis.
Appendix Table 8-1. Percent groundwater Flow values for slough: and
side channels,
Study Site Passage Reach
Percent Groundwater
Flow Values
Whiskers Creek Slough
Mainstem 2 Side Channel
Slough 8A
Slough 9
Slough 9A
1
1 I
III
IV
V
VH
VII
VIII
R&M Gage
%X
x
R&M Gage
11%
Appendix Table A-l
Study Site Passage Reach
Percenx Groundwater
Flow Vahues
Slough 11
Slough 19
Side Channel 21 b
Slough 21
I
1 I
111
R&M Gage
IV
V
VI
VI I
1
R&M Gage
1 I
IIIR
IIEL
Appendix Table A-l (Continued).
Study Si ee Passage Reach
Percect Groundwater
FlQW
Slough 22
a Passage reach is in one channel of a multi-channel reach of the study
soF"te,
Percentages are referenced from the RAM gage located in Slough 21.
The Manning Equation is assumed to be applicable to the low flow 2nd
shal low depth conditions in the passage reaches, The Manning Equation
is an empirical relationship between channel discharge and channel
geome t sy :
The energy gradient (S) is assumed to be represented by the water
surface slope at the cross section and the steeper of the upstream and
downstream slopes is assumed to govern the passage reach flow charac-
teristics. The channel wetted perimeter R) and area are ca%culated
from the surveyed cross section. Manni qg's roughness coefficient (n
assumed to be primarily a function of bed material size and channel
uniformity. For appl ication to the passage reaches, the roughness
values are assumed to be uniformly greater at the shallow depths associ-
ated with the passage analysis in comparison to the flood flow rouahness
values found in the literature (Chow 1959). The steps used to calibrate
the Manning Equation at each passage reach is summarized below:
1. Obtain a surveyed cross section at the passage reach.
2. Measure the water surface elevation and col lect corresponding
local flaw data.
Appendix Table A-2. Ranges of lfanning' s roughness coeff icbients is a
function of substrate size and channel unjformaity.
hness Cseff icient -------
Uniform Non-uni form
Substyate Material
Channel
(flu)
Au Anu
>and/Si 1 P (A) 0.03 -. 0,07 8,05 -- 0,011
SandlSi l t and
Gravel /Rubble/Cobble (B)
Rubbl e/Cobbl e/Boul der (C)
Bu Bnu
O,b5 -- 0,IO 0,07 - 0.1:
CU Cnu
0,06 - 0,12 0,88 - 0,%4
3. Classify substrate and channel uniformiv tto evaluate the
appl icable range of roughness values (Appendix Table A-2).
4. Obtain "che reach energy gradient from on-site water surface
measurements or from thalweg water surface profiles
5. Cal ibrate Manning's Equation by adjusting the roughness and
gradient val ues.
The roughness and gradient values were adjusted during equatjon call-
bration to reflect site conditions, as represented by the measured water
surface elevation and the local flaw evalua"cd din the Local Flow Dis-
tribution analysis. The roughness value for a passage reach was varied
within the appropriate range until the discharge calculated with the
Manning Equation approximated the measured discharge. For passage
reaches where the variations in roughness values did not yield an
appropriate discharge, the gradient values were adjusted. The average
of minimum water surface slope was selected to represent the energy
gradient if slopes from adjacent passage reaches were similar to the
modified value. Alternatively, the slope of the reach was calculated
from the thalwey water surface profile (Quane et a1 . 1984) and used when
calculated and measured discharges compared we1 I.
At passage reaches 1 acki ng surveyed water surface elevations, Manning ' s
Equation was cal i braled by comparison with ccil! brated equations from
adjacent and similar passage reaches. The passage reach energy
gradient, substrate size and channel uniformity were used as indices of
B
similarity.
At pa3sage reaches with low flows during cross section and water surface
elevatSon data collection, a potentially significant proportion of local
flow at the passage reach may be excluded by the flow computations using
the surveyed cross section data. Following the cal ibration of roughness
and gradient values, the Manning Equation in ruck low flow cases cal-
culated less discharge at a passage reach than the estimated discharge.
The calculated dischargz was then subtracted from the measured discharge
to estimate the amount of passage reach flow that was excluded using the
surveyed cross section. The excluded flow was assumed to be a constant
amount that would be continuously underpredicted by the cal i brated
Manning Equation. To evaluate the total passage reach discharge using
the Manfling Equation, the excluded flow was added to the calculated
discharge fol Iov~ing each computation. Apgendix Table A-3 1 ists the
values selected for calibration and the excluded flow at affected
passage reaches.
The frequency of occurrence of local flows at passage reaches may be
evaluated through the analysis of the flow contributions from ground-
water and precipitation runoff. Appendix Table A-4 presents the local
flows and the1 r corresponding frequencies of occurrence. The aeneral
Appendix Table A-3, Values of Manwik-ag" roughness snsedf iejeszt, energy gradient, and excluded Flow for cal ibration sf Manni nq a s
equation,
Substrate and Manning's
Passage Channel Uni f oemi ty Roughness Energy
Reach Gategory Coefficient Cradi en$ Study Site
Whi skers Creek Slough
Mainstem 2 Side Channel Bnu
8nu
Cn u
Cnsl
Cs%u
@nu
cu
Cnu
Bnu
Snu
BU
Bnu
Bu
Bu
Cnks
Cu
Bn u
Cnu
Gwu
Slough 9
Cnu
@nu
Bu
Bu
Cwu
8nu
Bnu
Cnu
Cn u
Cnu
Bnu
. . he" ij
Appendix Table 8-3 [GontS nued),
Study Site
Substrate and Manwing's
Passage Channel Uni foemi ty Roughness Energy
Reach Category Coefficient Gradient
Slough 47
Upper Side Channel 1%
Slough 19
Slough 20
Side Channel 21
Cnu
Bu
Snu
Cwu
Cnks
Cnu
Cesu
Cnu
Bwu
Bn ar
Bnps
Bn u
Bwu
Bnu
Bnu
BBTU
Gnu
Cnu
%$nu
Bnu
Bwad
Bwu
Appendix Table 8-4. Frequency of occurrence of local f ~OMS for successful (5) and unsuccessful (US) passage . ,r a ba:eClom correspoding to 15,000 cfs Susitna River dls~hdr~g
at Goid Creek and incjuding precipitation values from august. 20 to Septehner 20.
Requ i red
Reqpl i red Aequi red Sits
Base Flow Local BIow Surface Meter Precipibation
fcfsl acf s) (sFs9 I4n)
Required
Tal keetna
PrccSpitaa ion Percent
&in) Eaceedence -.
Passage asi in" Percent at -- Precipitation
Study Site Reach Area Runoff 15,6100 cfs US 3 US 5 US S US Coeff iciene
Slough 8A
Slough 919
Slough 1 1
Study SD te
Substrate and Manni ng8 s Exc! uded
Passge Channel Uni fobmi ty Roughness Energy Flow
Reach Ca tegsry Coefbici en$ Cr adi en& (cfs)
Slough 22 Cnu
Cnu
Cn u
a Substrate and channel uniformity categories are taken from Table 3 in Section 2.3.2.4.
Gradient from adjacent passage reach gradients.
Gradient from entire thalweg reach.
B
I Average of upstream and downstream gradient.
k-a
-@ " Hi nimum of upstream and downstream gradient.
No cross section data available.
Appendix Table A-4. Frequencv of occurrence of local flows for successful (5) and unsuccassful (US) passage for a basef)~~ correspoding to 15,000 cfs Susitna River discharge
at Cold Creek and including precipitation values from August 20 to Septehner 28. ----
Requ i red Wequi red
Requi red Wsqui red Site Ba l keetna
Base F?m Loca6 Flow Surface Water Brecipi eat ion Precipitation Percent
fcfs) (clfs) (cfs) (fn) (in1 Exceedence
Passage b as i n-ercent at Precipitation - ---
Study %i te lisesrh Area Runoff 15,000cfs US S US S US S US CocFffcient
Slough 9
Slough 11
Append4 x Table A-4 (Continued).
Requa red Wequl red
Wequi red Reqari red Sate Tslkeetne
Base F$w Local FSm Surf ace later Pfaclpitat Osn BsecBgi tation Percent
Cefs) fcf %I (C~S] (in) din) Enceederpce
Passage as i nb~ercent a% PseclpP tat ion - ----
Study SIte Reach Area Runoff 15,008cfs us S US 9 U5 5 US Coefficient
Upper Side Channel 11 I
6 1
Side Channel 20 B
ah
ill
I w
V
V I
Vl I
'VSll
0 X
Basin area evaluate4 from topographic maps frm the United States GeologCsaO Survey ~SCQ~C 1 :63,360)# Taikeeena Wts C-6, 0-1 and 8-6.
Crass section data not collected in field; requtsed Boeal f lo~a cannot be tvetuated.
" Locai flow estimated from field ~bscrvetjons. ' Precipitation docs not yield e surface rater contribution to local flor as no trfbutaries sre located upstream of the passage reach and runoff tntlltrater allvvirr, rail.
" Encecdence frequencies cannot be evajueted ss local flow data are not available.
approach used to evaluate the frequency of occurrence corresponding to a
specified local flow is described below:
1, Calculate the base flow for the period from August 20 to
September 20 at the R&M gage using the mainstem versus slough
discharge relationship. If a relationship has not been
evaluated at the site, assume a base flow at Passage Reach I
from the data collected for known mainstem flows,
2. Evaluate the base flow at each passage reach by multiplying
the base flow from Step 1 by the percent groundwater flow
value obtained through the local Flow Distribution analysis.
3. Evaluate the required surface water Sy subtracting the base
flow from the local flow estimated for successful passage.
4. Calculate the basin area upstream of the passage reach con-
tributing surface runoff.
5. Calculate the precipitation necessary to yield the required
suieface water,
6. Use the Precipitation Duration Curve at Talkeetna for August
Appendix Figure A-2) and adjust the daily precipitation by
the coefficients listed in Appendix Table A-5 to obtain the
frequency of occurrence,
Apjendfx Figure A..2. August Precipitation Duration Curve for the period
1972-1981 at. the Val keetna Weather Stat lon
from H-E 1484:.
A $Q
Appendix Table A-5, ?recipitation coefficients for determining precipi-
tation values at: selected sloughs using pvec-ipi-
tatisn values rei~rded at the Talkeetna b$~.eaEeher
de~ived from R&M 1984).
Study S i te River M!4e
~reci piation"
Cseffi ci ent
Slough 8A
Slough 9
Slough 21
d To obtain precipitation estimates for above sloughs, mu1 ti ply precipi-
tation at Talkeetna by the appropriate coefficient.
7, Repeat steps 3 through 6 using the local flow ~stimi.led Tor
unsuccessful passage.
Base flows from jroundwater contributions in the sloughs and side
channels were evaluated at the average mainstem d :A harge during the
period from August 20 to Sceptember 20. The average SusiQna River
discharge at Gold Creek for this period wcs estimated to be 15,000 cfs
detemined from the Flow duration curve developed in Sautner et al.
The slough versus mainstem discharge relationships used to
evaluate the base flows at Sloughs 8A, 9, and ll Gempe ~1 i ne pe pse comm
are listed below:
At sloughs and side channels where local flow versus mainstem discharge
relationships have not been evaluated, base flows corresponding to a
15,000 cfs mainstem discharge at Gold Greek were estimated from local
flow data. Slough Flows, measured on dates when the mainstem discharge
was 15,000 cfs, provided an estimate of' base flows. Alternatively,
local flows measured at the same site on different days were plotted and
extrapolated to yield 2 base flow for a mainstem discharge of 15,000
cfs. Data col lected during periods of high precipitation were excluded.
Appendix Table A-6 lists the base flows evaluated at specific sites.
Appendix Table A-6. Base flows for a mainstem dischar~e at Gold Creek
of 15,000 cfs,
Study Site
Local Flow
CPS
Lacation of
Local Flow Evaluation
Slough 8A
Slough 9
Slough 9W
Slough 11
Side Channel and
Slough 21
R&M Gage
R&M Gage
PRI
R&M Gage
R&M Gage
Precipitation events were assumed to contribute rainfall for 24 hturs to
pe~mj t comparison with the August Precipitation Duration Curve
The Precipitation Duration Curve (Appendix Figure 8-2
developed Prom daily precipitation records from 1932 to 1981, The
August Precipitation Duration Curve was assumed to be appl icable to the
August 20 to September 20 period as the rainfall records for August and
September appeared simi 1 as when compared. Tal keetna records were
adjusted using preci pi tation coeff icieslts for transfer of recorded data
Antecedent moisture condi itions were assumed invariable and a constant
surface water runoff to precipf tation percentage was selected for each
passage reach. Variations in .soil moisture prior to rainfall events may
affect the amount of precipitation which becomes surface water runoff;
in the precipitation frequency analysis, these variations were assumed
negligible. For Sloughs 8A, 9, 11 and 21, the runoff to precipitats'on
percentages ref lecled known topographic and soi 1 condi tions and were
selected Prom runoff coefficients presented in the R&M Consul tants Water
Balance report (R&M 1984b Sloughs and side channels with primarily
a1 1 uvial soi 1 watersheds were assigned a runoff coeff i ci enof f 0
percent. Steep slopes in the watershed would increase runoff; a runoff
coefficient of 65 percent would be used in the precipitatioo analysis.
For sloughs and side channel s with watersheds encompassing both steep
side slopes and alluvial materials, a runoff coefficient of 40 percent
was selected. Appendix Table A-3 lists the runoff coefficients used at
each site, t
~ LITERATURE CITED -
Chew, V.T. 1959. Open-channel hydraulics. MeGraw Hill, New York, New
Yark. 680 p.
Gemgerl in@, E. 1984. Personal Communication. Harza-ELasco.
Harza-Ebasco (H-E 1984. Slough geohydrology studies. Prepared for
Alaska Power Authority. Anchorage, Alaska,
Quane, T., P. Morrow, and T.W. Withrow. 1984. Chapter 1: Stage and
discharge investigations. In Report No, 3: Aquatic Habitat and
Instream Flow Investigations May - October 1983 by C. Estes and
D. Vincent-Lang, eds. Anchorage, Alaska.
R&M Consultants, Inc. 1982. Slough hydrology interim report.
Prepared for Acres American. Anchorage, Alaska.
. 1984a. R&M memorandum report on local runoff into sloughs.
Prepared for Harza-Ebasco. Anchorage, Alaska.
1984b. Water balance studies of middle Susitna River slouahs.
Draft. Prepared for Harza-Ebaseo. Anchorage, Alaska.
Sa~~~tnei-, J., L.J. Vining, and L.A. Rundquist. 1984, An evaluat on of
passage conditl'ons for adult salmon in slosigks and side channels of'
the middle Susitna River. Chapter 6 in 1984 Report No, 3: Aquatic
Habitat and Tnstream Flow Investigations May-October 1983
Estes, C.C. and D.S. Vincent-Lang, eds. Alaska Departn~ent of Fish
and Game Susi tna Hydro Aquatic Studies. Anchorage, A1 aska.
APPENDIX B
Passage Reach Distribution Maps
APPENDIX B: PASSAGE REACH DISTRIBUTION MAPS
The maps compiled in this appendix show the loeations of passage reaches
at selected slough and side channel study sites of the middle Susitna
Rlver identified during the 1984 open water season Appendix Figures B-1
These naps have been revised from those appearing in Sautner
to show the wetted area of each site at unbreached flows.
Locations of staff gages established in 1984 are desig~~ated on the
appropriate site maps. These maps were derived from aerial phostos of
the middle Susitna River,
4vpen.j i :c F ir;~ re B--1. Locd ;ions of passage reaches at Whiskers
Greek Slough during the 1984 open water
SPdSOn,
Appentfix Fi~ure R-2. . Locations of passage reaches at Mainstem 2
Side Channel during the 1484 open water
SeaSon=
ns of passage reaches at Slough 8A
during the 1984 open water season.
B-5
!\orler03i x - it-j~1i-e 8-4 . Locations of passage reaches at Slough 9
during the 1984 open water season.
Appendix Figure R-6. Locations of passage reaches at Slough 3A
during the 1984 open water season.
SUS/ TNA R/ VEW
@I34 PW PASSAGE REACH
WATER'S EDGE - - - DEWATEWED CHANNEL
@ RIVER MILE
Apperrd i x F igure B-7, Locations of passage reaches at Side Channel
10 as identified by the thalweg profile.
pB PASSAGE REACH I B
WATER'S EDGE
0EWABEREB CHANNEL
@ RIVER MILE
FEET
( Agpro~. Sco8ej
Locations of passage reaches at Slough 11 and
Upper SitPtt Channel II during the 1984 open
watca* season,
Locations of passage reaches at Slough 19
during the 1984 open water season,
Aoocndlx Fig8ri.e R-10, LoctltJons of passage reaches at Slough 20
during the 1984 open water season.
Locations of passa3e reaches at Side Channel
21 during the 1984 open water season.
PA PasSASE REACH
DEWATERED CHANPdEL
@ MILE
Appertdix Figure B-12. Locations of passage reaches at Slough 21
during the 1984 open water season.
;\ppend i:#: Figure R-13. Locations of passage reaches at Slough 22
during the 1384 open water season.
LITERATURE CITED
Sautner, J., L.J. Vining, and L.A, Wundquist. 1984. An evaluation of
passage conditions for adult salmon in sloughs and side channefs sf
the middle Susitna River. Chapter 6 in 1984 Report No. 3: Aquatic
Wabi tat and Instream Fl ow Investigations May-October 1983
Estes, C.C. and D.S. Vincent-Lang, eds. Alaska Department of Fish
and Game Susi tna Hydro Aquatjc Studies. Anchorage, A1 aska,
Thal weg Prof i 1 es of Passage Study Sites
APPENDIX C: THALWEG PROFILES OF PASSAGE STUDY SITES
Phis appendix contains thalweg prof1 les of slough and side channel
passage study sites il lustrating passage reaches identified during -the
1984 open water season Appendix Figures C-1 to C-13 With the
exception of Slough 19, these figures are revisions of thalweg profiles
grevlously presented in Sautner et ale The Slough 19 thalweg, .
which was surveyed for the first time in 1984, is also presented here.
Survey data used to complete the Slough 19 thalweg profile are
summarized in Appendix Table C-I. Survey data for the other study sites
are presented in Quane et a1 . These thalweg profiles are only
intended ta show approximate locations of passage reaches within each
study site and due to their limited accuracy, should not be used for
other, more detai 1 ed analyses.
WHSiSKERS CREEK SLOUGH
THALWEG PROFILE
? - f I !? 'ilc,uqlt
showing approximate locations of passage
reaches,
Appendix Figure C-2. Thalweg profile of Nainstem 2 Side Channel
showing approximate 1 acat i ons sf passage
reache?,
SLOUGH 8A
THALWEG PROFiLE
Appendix Figure C-3, Thalweg profile of Slough 88 showing
approximate locations of passage reaches.
Appendix Figure C-4. lhalweg profile of Slough 9 showing approximate
locations af passage reaches.
St@% CHANNEL 10
VHkLWE6 PROFILE
Appendix Figure C-6. Thalweg profile of Side Channel 10 showing
approximate locations of passage reaches.
STREAMBED STATlQW I fee8 1
Appendix Figure C-7. Thalweg profile of Slough 11 showing
approximate locations of passage reaches.
Appendix Figure C-8.
UPPER SlOE CHANNEL 81
THALWEG PROFILE
SURVEY OAT61 @SO820
f HALWEO GRADIENT1 9.2 FELTlUILE
THALVEG EBEVIVOBN PROFBLEa -
PASSAGE WEICH* PI
8138AQE REACH CROSS SECTSOMI as irt-Poaetr hm5eawl
Thalweg profile of Upper Side Channel 11
showing approximate 1 ocations of passage
peaches,
SLOUGH 19
WHAWEG PROFILE
SURVEY DATE* 84C01@
THBLWEO GRADIENT* 98.0 PEEV/Mi%E
SBHACWEO ELf VATBOH PROFILE:
PASSAGE REACH* fi
PASSAGE REACH CROSS SECTIQWI gs (A@p@OX LQC~~~~~
Appendix Figure C-9. Tkalweg profile of Slough 19 showing
approxin~ate locations of passage reaches.
Appendix Figure C-11. Thalweg profile of Side Channel 22 showing
approximate locations of passage reaches.
SLOUGH PI
YHBLWEG PROFihE
Appendix Figure C-12. Thalweg profile of Slough 21 showing
approximate locations of pascage reaches.
App~ndix Figure C-13. Thalweg r~rofi 1 t? of Slough 22 showing
approximate locatinns of passage reaches.
Appendix Table C-1. Sumary of survey data collected for the thalweg profile cnf Slough 99 daring the
1984 open water field season.
LOCATION OF THALWEG: Slough 19
SITE FNM: 0.1 cfs
USGS DISCHARGE: 5200 cfs
DATE : OCTOBER 18, 1984
TBM ID: !\DF&G 140,O WB 830914
Slough 19
Thal weg Mater
Station Elevation Depth WSEL Habitat
SAS I
BOS 1
SISA
SIB0
SISA
SISA
CBSA
BOSA
SISA
CBSA
SISA
SISA
SISA
SISA
SISA
SISA
SISA
SISA
SISA
SISA
BOCO
Mid-Ri $$I e
Riff le/Pool
Mi d- Pool
Pool Constriction
MI d-Po01
Pool Constrictjon
Mid-PosI
Pool/RifCle
Mid-Rdffle
Ri ffle/Pool
MSd-Pool
Pool/Riffle
Riffle/Pool
Mid-Pool
Mid-Pool, t4outh
Pool /Run
H4 d-Run
Run/Pool
Mi d-Pool
Pool /Run
Run/ Po01
Mi d--PosB
Pool /Ri f Ti 2
Ri f FlejPoaB
Appendix Table C-l Continued) .
Thal weg Water
Station Elevation Depth WSEL
Overflow Channel f
1,14
8,28
Ocp 13
0,01
DRY
ICE
LO3
6,18
0 00
ICE
0,35
ICE
8.00
2,03
DRY
DRY
SISA
SISA
SGSA
LGSG
LGSG
SAbG
SISA
S A
BOS 1
COB0
CORU
CORU
CORU
SASI '
CORU
CORU
SISA
CBRU
CORU
Mid-P~sl
Pool/Riffle
Mid-Riffle
Mld-Riffle
Mdd-Riffle
Ai Cfle/Pool
Mi d-Pool
Pool/Riffle
Mid-Riffle
Riff le/Pool
Mid-Pool
Pool/Riffle
Riffle
Mid-Rdffle
Nigh Point in Over-
Flow Channel
Mainstem Waters Edge
M% d-Psol
High Point in
Overf 1 ow Channel
blainstem Waters Edge
ti Substrate code defined in Methods Section see Table 2).
LITERATURE CITED
Quane, T., P, Morrow, and TOW. Withrow. 1984. Chapter I: Stage and
discharge investigations. In Report No. 3: Aquatic Wabi tat and
Instream Flow Investigations May - October 1983 by C. Estes and
D. Vincent-Lang, eds. Anchorage, Alaska.
Sautner, J,, L.J. Vining, and L.A. Rundquist. 1384. An evaluation of
passage conditions far adult salmon in sloughs and side channels of'
the middle Susitna River. Chapter 6 in 1984 Report No, 3: Wquati :
Habitat and Xnstream Flow Investigations May-October 1983
Estes, C.C. and D.S. Vincent-Lang, eds. Alaska Department of Fich
and Game Susitna Hydro Aquatic Studies. Anchorage, Alaska.