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HomeMy WebLinkAboutAPA2945SUSITNA HYDROELECTRIC PROJECY. FEDERAL ENERGY REGULATORY COMMISSION PROJECT No. 7114 .. PREPARED BY li'ihey& Associates Aquatic Resource Specialists 11uncR CONTRACT TO ~~R-HO ru~£ o §00£®@@ 1425 rNA JOINT VENTURE .sa F472 no.2945 RESPONSE OF AQUATIC HABITAT SURFACE AREAS TO MAINSTEM DISCHARGE IN THE TALKEETNA-TO-DEVIL CANYON SEGMENT OF THE SUSITNA RIVER, ALASKA FINAL REPORT NOVEMBER 1985 DOCUMENT No. 2945 Alaska Resources Library & fufonnatioo SeTVIces 1\nchorage,AJaska SUSITNA HYDROELECTRIC PROJECT Response of Aquatic Habitat Surface Areas to Malnstem Discharge In the Talkeetna-to-Devil Canyon Segment of the Susltna River, Alaska By Sharon A. Kl lnger-Kingsley LaMoyne Reynolds E. Woody Tr I hey Trlhey and Associates Under Contract To Harza-Ebasco Susltna Joint Venture Prepared For Alaska Power Authority Final Report November 1985 ARLIS Alaska Resources Library & Information Services Libra!>' Building, Suite Ill 321 f Providence Drive Anchorage, AK 99508-4614 Document No. 2945 Susitna File No. 4.3.1.3 ov NOTICE ANY QUESTIONS OR COMMENTS CONCERNING THIS REPORT SHOULD BE DIRECTED TO THE ALASKA POWER AUTHORITY SUSITNA PROJECT OFFICE N ACKNOWLEDGEMENTS Th 1 s work was undertaken in cooper at I on with the AI aska Department of FIsh and Game Sus I tna Hydro Aquatic Study Team and R & M Consu I tants, Inc., Anchorage, Alaska. ADF&G SuHydro personnel participated in the derivation of definitions for the various habitat types and the development of the aquatic habitat classification key. The aerial photography missions were scheduled through Mr. Steve Bredthauer, R & M Consu I tants, Inc. He did an exceptional job given the highly variable nature of streamflow and weather conditions. Aerial photography was flown and photo mosaics and enlargements prepared by Air Photo Tech, Inc., and North Pacific Aerial Surveys, Inc., Anchorage, Alaska, under contract to the Harza-Ebasco Susitna Joint Venture. TABLE OF CONTENTS I NTRODUCT I ON ••.•.•••.•••••••••••••••••••.••• • • · · • • · · · · · • • • • • • • • METHODS ••••••••••••.•••• ••••••••••••••••••••••••••••••·•••····· 2 Habitat Types Designations ••••••••••••••••••••••••• ••••••• 2 FIe I d Methods ......................... · · · · · · · · · · · · · · · · · · · · 3 Office Procedures ................. ··· .... ················· 5 Photo Plates and Enlargements •••••••••••••••••••••••• 5 Habitat Type Boundaries •••••••••••••••••• •••••••••••• 5 D i g it i z i ng ••.••••••••..•.•••..••••..•..••.... · · • · · · · · 7 Data Base ..........•...•.......... ··················· 7 Ana i ys is Procedures ...................... · · · · · · · · · · · · 7 RESULTS ....••..•..•....••.•.•..••••..•..•... · · • · • • · · · · · · · • • • • · • 8 DISCUSS I ON ••••••••••••••••••••••••••••••••••••••••••••••••••••• 15 REFERENCES •....••.•..•.•.••••..•.••..•.....•.•..............••• 19 APPENDICES PREFACE The goa I of the A I ask a Power Authority In IdentifyIng envIron menta I I y acceptable flow regimes for the proposed Susltna Hydroelectric Project Is the maintenance of existing fish resources and levels of production. This goal Is consistent with mitigation goals of the U.S. Fish and W II d II fe ServIce and the A I ask a Department of FIsh and Game. Maintenance of naturally occurring fish populations and habitats is the preferred goal In agency mitigation pol lcles. In 1982, following two years of baseline studies, a multi-disciplinary approach to quantify effects of the proposed Susltna Hydroelectric Project on existing fish habitats and to identify mitigation opportunities was Initiated. The instream Flow Relationships Studies focuses on the response of fish habitats In the middle Susltna River to Incremental changes In mainstem discharge, temperature and water quality. As part of this multi-disciplinary effort, a technical report series was planned that would (1) describe the existing fish resources of the Susltna River and Identify the seasonal habitat requirements of selected species, and (2) evaluate the effects of alternative project designs and operating scenarios on physical processes which most Influence the seasonal availability of fish habitat. The summary report for the IFRS, the lnstream Flow Relationships Report <IFRR), (1) Identifies the biologic significance of the physical processes eva I uated In the techn I ca I report serIes, (2) integrates the findings of the technical report series, and (3)provldes quantitative relationships and discussions regarding the Influences of Incremental changes in stream f I ow, stream tern perature, and water qua I I ty on fIsh habitats in the middle Susltna River on a seasonal basis. The IFRR consists of two volumes. Volume I uses project reports, data and professional judgement available before March 1985 to Identify evaluation species, Important I lfe stages, and habitats. The report ranks a variety of physical habitat components with regard to their degree of Influence on fish habitat at different times of the year. This ranking considers the biologic requirements of the evaluation species and life stage, as well as the physical characteristics of different habitat types, under both natural and anticipated with-project conditions. Volume II of the IFRR will address the third objective of the IFRR and provide quantitative relationships regarding the Influences of Incremental changes In streamflow, stream temperature and water quality of fish habitats in the middle Susltna River on a seasonal basis. The influence of Incremental changes in streamflow on the avallabil lty and quality of fish habitat Is the central theme of the IFRR Volume II analysis. Project Induced changes in stream temperature and water quality are used to condition or qualify the forecasted responses of fIsh habItat to I nstream hydrau I I cs. The In f I uence of stream f I ow on fish habitat will be evaluated at the microhabitat level and presented at the macrohabitat level In terms of a composite weighted usable area curve. This composite curve will describe the combined response of fish habitat at alI sites within the same representative group to Incremental changes In malnstem discharge. Four tech n i ca I reports are beIng prepared by E. Woody Tr I hey and Associates in support of the IFRR Volume II analysis. The function of each report Is depicted In a flow diagram and described below. 1. Quantify Wetted Surface Area Response 2. Assess the Representa- tiveness of Modeled and Non-modeled Sites 3. Determine Site Specific Hydraulic Conditions 1. 4. Quantify Streamflow Dependent Habitat Response Functions for Juvenile Chinook and Spawning Chum Salmon RESPONSE OF AQUATIC HABITAT SURFACE AREAS TO MAINSTEM DISCHARGE IN THE TALKEETNA-To-DEVIL CANYON SEGMENT OF THE SUSITNA RIVER, ALASKA This report identifies five aquatic habitat types within the middle Susitna River directly influenced by changes in mainstem discharge and presents the necessary photography and surface area measurements to quantify the change In wetted surface area associated with Incremental decreases In malnstem discharge between 23,000 and 5,100 cfs. The report also describes the Influence of malnstem discharge on habitat transformations and tabulates the wetted surface area responses for 172 specific areas using the ten representative groups presented in the Habitat Characterization Report. Surface area measurements presented In this report provide a basis for extrapolating results from intensively studied model lng sites to the remainder of the middle Susltna River. 2. 3. 4. -iii- CHARACTERIZATION OF AQUATIC HABITATS IN THE TALKEETNA-TO-DEVIL CANYON SEGMENT OF THE SUSITNA RIVER, ALASKA This report describes the characterization and classification of 172 specific areas Into ten representative groups that are hydrologically, hydraul jcal ly and morphologically similar. Emphasis is placed on the transformation of specific areas from one habitat type to another In response to incrementa I decreases In mainstem discharge from 23,000 cfs to 5,100 cfs. Both modeled and non-modeled sites are classified and a structural habitat Index Is presented for each specific area based upon subjective evaluation of data obtained through field reconnaissance surveys. Representative groups and structural habitat indices presented in this report provide a basis for extrapolating habitat response functions developed at modeled sites to non-modeled areas within the remainder of the river. HYDRAULIC RELATIONSHIPS AND MODEL CALIBRATION PROCEDURES AT 1984 STUDY SITES IN THE TALKEETNA-To-DEVIL CANYON SEGMENT OF THE SUSITNA RIVER, ALASKA This report describes the influence of site-specific hydraul lc conditions on the availability of habitat for juvenile chinook and spawning chum salmon. Two aquatic habitat models are appl led to quantify site-specific habitat responses to incremental changes in depth and velocity for both steady and spatially varied streamflow conditions. Summaries of site- specific stage-discharge and flow-discharge relationships are presented as well as a description of data reduction methods and model calibration procedures. Weighted usable area forecasts are provided for juvenile chinook at eight side channel sites and for spawning chum salmon at 14 side channel and mainstem sites. These habitat response functions provide the basis for the instream flow assessment of the middle Sus I tna RIver. RESPONSE OF JUVENILE CHINOOK AND SPAWNING CHUM SALMON HABITAT TO MAINSTEM DISCHARGE IN THE TALKEETNA-To-DEVIL CANYON SEGMENT OF THE SUSITNA RIVER, ALASKA This report Integrates results from the surface area mapping, habitat characterization, and hydraulic modeling reports IQ provide streamflow dependent habitat response functions for juvenile chinook and spawning chum salmon. Wetted surface area and weighted usab I e area are the pr Inc i pa I determInants of habItat IndIces provIded In Part A of the report for juvenile chinook at each specific area and the ten representative groups Identified in the habitat characterization report. Part B of this report provides habitat response functions for existing chum salmon spawning sites. The habitat response functions contained In this report w11 I be used for an incremental assessment of the rearing and spawning potential of the entire middle Susltna River under a wide range of natural and with-project streamflows. -iv- INTRODUCTION The proposed Susitna hydroelectric project will alter the natural streamflow regime of the Susltna River downstream of River Mile 232, the upstream most extent of the Watana Impoundment. The river segment upstream trom the Chul ltna River confluence (Talkeetna) at River Mile 98 would experience notable alterations in naturally occurring streamflow patterns due to Its proximity to the proposed dam sites and the I lmlted amount of influence that tributary inflows have on total discharge In this river segment. With-project discharges are expected to be lower than naturally occurring flows during summer and higher than naturally eccurrlng flows In the winter. These altered flows are expected to affect the amount and seasonal avallabll ity of aquatic habitats. This report IdentIfIes the I ocat I on and descrIbes the area I extent of various aquatic habitat types within the Talkeetna-to-Devil Canyon segment of the Susltna River (hereafter referred to as the middle Susltna River) at different malnstem discharges. These data, In combination with the results of other studies focusing on biological aspects of aquatic habitats within this river segment, will facilitate forecasting the effects of project-Induced changes to natural streamflows on the availability of aquatic habitat for anadromous and res I dent fIsh. Aerial photography Interpretation, along with field reconnaissance, Is being used to Identify and map various aquatic habitat types in the middle Susltna River. In 1984 initial work on aquatic habitat mapping and surface area measurements determined the location and amount of -1- various aquatic habitat types. Four sets of aerial photographs were taken at malnstem discharges of 23,000; 16,000; 12,500; and 9,000 cfs, as measured at the U. S. Geological Survey (USGS) Gold Creek gaging station (KI Inger and Trihey 1984). These photos are discussed in this report (with the exception of the 9,000 cfs photography) together with the surface area measurements at four additional streamflows: 18,000, 10,600, 7,400, and 5,100 cfs. The 18,000 cfs discharge fal Is within the 16,000 to 23,000 cfs range, where several side sloughs and side channels become inundated by malnstem water. The lower three discharges provide a good basis for evaluating low flow conditions In the river. The surface area measurements obtained In 1984 from the 9,000 cfs photography were omitted from this report because the presence of snow and ice In the 9,000 cfs photography made It difficult to accurately determine the water's edge and measure the wetted surfaces (Klinger ahd Trihey 1984) (also see Discussion). The adverse Influence of shoreline Ice and snow cover on the accuracy of the 9,000 cfs data set was confirmed In a comparison between the 1984 surface area measurements obtained from the 9,000 cfs photography and the 1985 surface area data obtained at 7,400 and 10,600 cfs (Klinger 1985). Surface area measurements for the seven dIscharges eva I uated In thIs report provide an adequate basis for identifying the transformation of specific areas from one habitat type to another as a result of reductions in streamflow, as wei I as for quantifying the response of wetted surface area for habitat types and specific areas over the range of streamflows between 5,000 and 23,000 cfs. However, although wetted surface area may be used as an Indicator of habitat availability, it does not represent habItat qua I I ty. ThIs report, therefore, does not contain any statements concerning the suitabll ity of the various habitat types for fIsh, nor does It contaIn cone I us Ions regardIng the response of habitat qual lty to changes In malnstem dlscharg& METHODS Habitat Type Designations The total wetted surface area of the middle Susltna River was classified Into six general aquatic habitat types: malnstem, side channel, side s I ough, up I and s I ough, trIbutary mouth, and tributary. These habitat types were established during Ice-free conditions from physical c h a r act e r I s t I c s of the en v I ron men t v I s u a I I y ev I dent I n a e r I a 1 photography or hel !copter overflights and do not necessarily depend upon any particular degree of uti I lzatlon by fish (figure 1). A description of the types follows. The following brief descriptions were used to Identify the six aquatic habitat types evaluated In this study. These definitions are I lmlted to visually recognizable physical characteristics present during ice-free conditions that are easily Identified during helicopter reconnaissance flights. -2- Mainstem habitat types are those channels of the river that normally convey streamflow throughout the entire year. They are visually recognizable by their turbid, glacial water and high velocities. In general, they convey more than 10 percent (approximate) of the total flow passing a given location. Side Channel habitat types are also characterized by turbid, glacial water. Velocities often appear lower than in malnstem sItes. In genera I, they convey I ess than 1 0 percent (approxImate) of the total flow passing a given location. Side channel habitat may exist In wei 1-deflned channels or in areas possessing numerous Islands and submerged gravel bars. When the upstream berms of side channels are dewatered and the channels contain clear water, they are classified as side slough~ SIde s I ough habitat types contaIn c I ear water. Sma II trIbutarIes, upwelling groundwater, and local surface runoff are the primary sources of clear water for these areas. Side sloughs have non- vegetated upper thalwegs that are overtopped during periods of moderate to hIgh rna I nstem dIscharge. When these areas are overtopped they convey turbid water and are then classified as side channels. Upland slough habitat types also contain clear water and depend on small streams, upwel I lng, and local surface runoff for their water supply. Upland sloughs possess vegetated upper thalwegs that are rarely overtopped by malnstem discharge. Tributary mouth habitat types are clear water areas that exist where tributaries flow Into malnstem or side channel habitats. This habitat type Is manifest as a clear water plume extending out Into the turbid receiving water. Tributary mouth habitat also extends upstream Into the trIbutary to the upper extent of any backwater In f I uence that mIght ex I st. The surface area of tributary mouth habitat is affected both by tributary discharge and malnstem stage. Tributary habitat types are those reaches of tributary streams upstream of the tributary mouth habitats. Tributary habitat types have not been evaluated In this analysis because tributary habitat is not Influenced by malnstem discharge. Non-wetted areas were classified as either vegetated Islands or gravel bars. Areas within the control corridor that were quantified but not relevant to the surface area analysis were classified as "background." For a more detailed description of each aquatic habitat type see the Alaska Department of Fish and Game Susltna Hydro Aquatic Studies (1983). Field Methods For the seven mainstem discharges studied In the middle Susltna River, black-and-white aerial photographs were obtained at an approximate scale of 1 Inch= 1000 feet, with a 60 percent overlap between adjacent photos. The dates of the photography and rna I nstem dIscharges as measured at the USGS Gold Creek gaging station (No. 15292000) at the time of photography are presented In Table 1. -3- Table 1. Dates and malnstem discharges at which aerial photography of the middle Susltna River was obtained. .Dirl:.e Discharge (cfs) 6-1-82 23,000 8-24-80 18,000 9-11-83 16,000 9-6-83 12,500 9-9-84 10,600 10-4-84 7,400 10-14-84 5,100 Hel !copter reconnaissance fl lghts were conducted over the middle Susltna River at malnstem discharges similar to those at which the aerial photography was obtaI ned. Our I ng each of these reconnaissance f I I ghts, aquatic habitat types were Identified using the key presented as Figure 1, and their locations were mapped on 1 Inch= 1000 feet scale bluellne prints of the Susltna River. Dewatered gravel bars and streambank areas were sketched on the bluel lne prints as were boundaries of the various habitat types. I Distinguishable Surface Water Source of Some Significance I Clearwater flow not likely to be influenced by mainstem water surface elevation I Surface area of tributary habitat I I Clearwater plume or flow likely influenced by mainstem water surface elevation Surface area of tributary mouth habitat Figure 1. Vegetated upper thalweg Surface area of upland slough habitat Indistinguishable or Insignificant Surface Water Source Non-vegetated upper thalweg Surface area of side slough habitat Total Surface Area of River Corridor on Photo Mosaics I Total Wetted 11-------------------'---------------;l Total Non-wetted I Surface Area 1 I Surface Area Channel conveys .:::10% of total flow Surface area of sidechannel habitat Turbid, Glacial Water I Channel conveys ::>-10% of total flow Surface area of mainstem habitat I Surface area vegetated islands and river corridor 1 l Surface area exposed streambanks and gravel bars Key to aquatic habitat classification for the middle Susltna River CRM 101 to 149). -4- Office Procedures Photo Plates and Enlargements Photographic mosaics were prepared from the overlapping black-and-white photos to provide continuous 1 Inch= 1000 teet coverage for each of the seven discharges. The photo mosaics were subdivided Into eighteen sections of approximately the same length, with a small amount of overlap between adjoining river sections and a set of eighteen 4-1/2 inch by 15 inch photoplates was printed for each of the seven discharges (Appendix 1). For the sets of photography taken at 23,000; 18,000; 16,000; and 12,500 cfs, each photo plate was carefully examined and areas that were too small In size to provide detailed resolution were en I arged to a sea I e of 1 Inch = 250 feet. Entire sets of photography taken at 10,600; 7,400; and 5,100 cfs, were enlarged to a scale of 1 Inch = 250 feet. Habitat Type Boundaries Aquatic habitat boundaries mapped on blue( ine prints during the helicopter reconnaissance fl lghts were transferred to corresponding sets of photographs. Figure 2 provides an example of the technique used for the photography taken at 23,000; 18,000; 16,000; and 12,500 cts. The technique used for the photography taken at 10,600; 7,400; and 5,100 cfs was essentially the same, with the exception that enlargement areas were not required because the entire set of photography was printed at the scale of 1 Inch= 250 feet. Matchlines were drawn on adjoining photo plates to ensure that habitat areas within overlapping sections near the -5- edges of the plates were not counted twice. The boundary of each enlargement area was establ lshed using prominent topographic features In the photography and drawn on both the plate and the individual en I argement. This ensured that areas wIthin the en I argement cou I d be summed and compared with the en I argement area on the pi ate. The external boundaries of the total area to be Included in the surface area ana I ys Is (contra I area) were defIned on each pI ate, so that sub- areas within the control area could be totaled and compared with the total control area of that plate. In many cases, It was necessary to go beyond the river channel boundaries to establish an Identifiable constant control area boundary. The area I ocated between the control area boundary and the river channel was digitized (see below) as "background" (refer to Figure 2b ). In addition to del lneatlng habitat type boundaries, Individual channels, referred to as "specific areas," were also delineated and digitized. This enabled the habitat type at a given location to be tracked at different malnstem discharges. Close examination of the habitat type mapping revealed that habitat type at a given location may not remain the same over a range of discharges. In general, the geographical I ocat I on and persistence of certa l n habItat types, such as tr l butar l es and their mouths, are fixed, although their surface areas may respond significantly to changes in discharge. In other cases, transformations of one habitat type Into another may occur as river stage Increases or decreases. For more detal Jed description of the methodology and results of the habitat transformation analysis see Appendix 2. MPLE OF A SUSITNA RIVER SEGMENT WITH HABITAT TYPES MAPPED & CLASSIFIED. 16 OQ cfs -6- I ] J J _j _j J nlgltlzlng In this report, digitizing refers to the process of calculating the area within a perimeter circumscribed on the aerial photographs. Area calculations were made using a Numonics Model 2400 DigiTablet and Electronic Graphics Calculator connected to an Epson HX-20 Notebook Computer. Prior to digitizing each photo plate and enlargement, boundaries were drawn around each wetted and non-wetted habitat element. By tracIng the per I meter of a gIven area wIth the Numon i cs DIg I Tab I et cursor, the area circumscribed Is calculated by the Graphics Calculator to an accuracy of 0.01 square Inch. This accuracy Is greater than that of del lneatlon and operator tracing error. Digitizing strategy consisted of digitizing the control area, the enlargements (if any> and elements within the control area. If enlargements were present, the total area of the enlargement was digitized, followed by the elements within it. Each area calculation was performed twice. If the percent error between the two measurements was greater than five percent, the area was redlgitlzed until the percent agreement was less than five. An Interactive computer program was developed for the HX-20 which prompted the digitizing operator for the plate number, flow code, control area number, enlargement number (If any>, enlargement factor, habitat code, element number, specific area river mile number, and the digitized area (transferred from the Graphics Calculator}. The program checked percent agreement for each measurement and performed the summation of elements for comparison with the Initial control area measurement. -7- Data Base Surface area measurements that had been stored on the Epson magnetic tape cassettes were transferred Into a computerized data base for storage, sorting, and subsequent analysis. Each Individual surface area measurement was entered as a separate record that enabled Identification by discharge, photograph (corresponding to a river mile Index}, Individual area number, and specific area river mile number, If appropriate. Correct I on factors were entered to standardIze to a common sea I e of 1 Inch= 1000 feet. Due to prevail lng weather factors at the time of the aer i a I photography f II ghts, s I I ght varIatIons In sea I e occurred in the various photo sets. Surface areas within enlargement areas and for those sets of photos printed entirely at the enlarged scale were divided by a factor of 16 to account for the fourfold difference in scale between 1 inch = 250 feet and 1 Inch = 1000 feet. Analysis Procedures Surface areas were summed by habitat type for the entire river corridor between Talkeetna and Devil Canyon for each of the seven discharges. Percentages of the total river surface area represented by each aquatic habitat type were calculated. Surface areas of Individual channels (specific areas} were also determined. -l i ] l _j J J I _j __j Local lzed changes In channel geometry which occurred as a result of high flow events in 1981 CKIInger-Kingsley and Trihey 1985) resulted in some InconsIstent surface area measurements for the 18,000 cfs photography. These Inconsistencies were considered an artifact of using photography obtaI ned before and after a major f I ood event. The 18,000 cfs photography Is the only pre-1981 condition analyzed, whereas post-1981 conditions are represented by six sets of photography with flows ranging from 5,100 to 23,000 cfs. Because the change In surface area of aquatic habitat Is a function of discharge and channel geometry, the middle Susltna River was subdivided Into four subsegments, each possessIng so mew hat d 1 f ferent geomorphological characteristics. RM 101 to 113 (Talkeetna-to-Lane Creek) Is a relatively channel lzed subsegment of the middle river with few mid-channel vegetated Islands or gravel bars and few side channels branching off from the malnstem. RM 113 to 122 <Lane Creek-to-Curry) Is a more braided subsegment with mid-channel Islands and side channels branching from the malnstem. RM 122 to 138 <Curry-to-Gold Creek) Is a braided subsegment with large mid-channel Islands and gravel bars and numerous side channels branching off from the malnstem. RM 138 to 149 (Gold Creek-to-Devil Canyon) Is a more channelized subsegment with some large side channels branching off from the malnstem. Total surface areas of each habitat type within these subsegments were determined to focus attention on the diversity of habitat types and surface area responses among subsegments with different morphologic characteristics. -8- The percent change In habitat type surface area between that present at 23,000 cfs and at the other discharges of Interest was calculated. Average monthly discharges for the Susltna River at Gold Creek range from 1 ,500 cf s In wInter to 28,000 cfs durIng summer wIth an average annual discharge of 9,700 cfs (figure 3a). Snowmelt runoff during June and early July accompanied by glacial melt and rainfall runoff during Ju I y and August provIde stab I e and persistent high summer dIscharges (figure 3b, c, d). From an analysis of the hydrologic data, it was determined that the aerial photography obtained at a malnstem discharge of 23,000 cfs represents a typical mid-summer discharge for the middle Susitna River. Therefore, this photography was used to depict basel lne mId-summer cond i tl ons. RESULTS Total surface areas for aquatic habitat types In the middle Susltna River are presented in Table 2. In some cases, such as for tributaries and their mouths, habitat type Is associated with specific geographical location and the habitat type persists over a broad range of streamflows even though the surface areas may respond sIgnIficant I y to changes In discharge. In other Instances, specific geographic locations transform from one habItat type Into another as r lver stage Increases or decreases. J J J j J A. B. 30,000 ......-----------------, 105 8 6 25,000 20,000 15,000 10,000 5,000 Iii ~ Q) ~ ftl .r. u "' i5 Average Monthly----. ONDJ FMAMJ J AS Months c. 105 8 6 4 r---r--t- 2 ' 104 8 6 4 2 103 8 6 4 2 JULY 102 0 1 0 20 30 40 50 60 70 80 90 1 00 % of Time Discharge Equalled or Exceeded Q) 01 .... ftl .r. u "' i5 4 2 104 8 6 4 2 103 8 6 4 2 10 2 r... r---r- -......... ~ JUNE ~ _j_ 0 1 0 20 30 40 50 60 70 80 90 1 00 % of Time Discharge Equalled or Exceeded 105 8 6 4 2 104 8 6 4 2 103 8 6 4 2 10 2 D. ['.... ......._ -~-- 1\ AUGUST __l_ I 0 1 0 20 30 40 50 60 70 80 90 1 00 % of Time Discharge Equalled or Exceeded Figure 3. Average annual discharge and average monthly discharges for the Susltna River at Gold Creek (adapted from Scully, Leveen, and George 1978); b,c,d. Monthly flow duration curves for the Susltna River at Gold Creek (adapted from Acres AmerIcan Inc. 1983 ). -9- Surface area values presented in Table 2 were plotted to II lustrate the surface area responses of Individual habitat types In response to changes in mainstem discharge (figure 4). Surface areas of malnstem and side channel habitats were smaller at lower discharges. Concurrently, exposed gravel bar surface areas were larger at lower discharges. S!'de slough surface area Increased w lth decreasing discharge down to a mainstem discharge of 7,400 cfs, and then decreased at 5,100 cfs. Upland slough surface area remained relatively constant over the range of mainstem discharges, decreasing somewhat at 5,100 cfs. Surface area of tributary mouth habitat was largest at intermediate flows of 16,000 and 12,500 cfs. Vegetated· bar surface area remal ned rei ati vel y constant over the range of mainstem discharges. Exam I nat I on of the data revea Is InconsIstent surf ace area measurements for side channel and side slough habitat types for the 18,000 cfs photography. Side channel surface area is lower and side slough surface area is higher than values expected from interpolation between data points at 16,000 and 23,000 cfs. Exam I nation of flow records for the middle Susltna River reveal that July and August 1981 were periods of relatively continuous high flow events CKI lnger-Kingsley and Trihey 1985). In addition, comparison of stage-discharge relationships prepared before and after July-August 1981 shows a 0.25 f~ reduction In stage for equivalent discharges <USGS 1972, 1982). This suggests that scouring occurred during the high flow events of 1981. This Is consistent with the observation of less side slough and more side channel habitat surface area measured on post-1981 photography. As channels were scoured, lower malnstem discharges would be required to ] ] ] l J ] I _j J J j J J J overtop the head berms, resulting In more side channel surface area and less side slough surface area at a given discharge after 1981 than prior to 1981. Table 3 presents the percentage of the total river corridor represented by each habitat type for each of the seven malnstem discharges. Table 4 presents the percent change In the surface area of each habitat type at each discharge as calculated from a baseline discharge of 23,000 cfs. The m I dd I e Sus I tna RIver was dIvIded Into four subsegments based upon differing geomorphological characteristics. These subsegments extend from approximately river miles (RM) 101 to 113, 113 to 122, 122 to 138, and 138 to 149. Because of dIfferences In the amount of surface area wIthIn each rIver subsegment and the desire to accent the response of habItat surface areas withIn the r lver subsegments, surface areas for the various habitat types are reported as the percent of total area In the subsegment river corridor (figure 5). Figure 6 presents a relative comparison of total surface areas calculated for various habitat types within the entire Talkeetna-to-Devil Canyon segment and within the four subsegments In response to changing malnstem discharge. -10- 1 j l l J J _I J J J Table 2. Total surface areas by habitat type within the middle Susitna River. Surface Area (acres) by D I scllaq~e Habitat Type 5.100 cts 7.400 cts 10.600 cfs 12,500 cfs 16,000 cts 18,000 cfs 23,000 cfs Malnstem 2453.0 2595.1 2789.8 2850.4 3158.5 3316.0 3737.2 Side Channel 768.2 854.0 982.9 1095.5 1222.2 952.0 1240.7 Side Slough 118.8 145.6 134.8 118.1 85.8 116.1 52.5 Upland Slough 16.4 20.8 21.5 22.0 22.6 24.6 24.4 Tributary Mouth 15.6 15.5 18.6 26.2 25.3 18.4 12.1 Gravel Bar 2522.9 2299.6 1852.4 1727.7 1419.2 1249.4 815.8 Vegetated Bar 1958.5 2140.3 2079.3 1919.1 2011 .4 1985.2 1718.4 -11- 5000~-------------------------------------------------, 1000 100 so Figure 4. MAINSTEM • __...,_..,..Lc..-----...->-=: UPLAND SLOUGH: /ZMOUTH 5 10 15 -3 Mainstem Discharge at Gold Creek (x10 cfs) 20 Surface area responses to malnstem discharge In the middle Susitna River <RM 101 to 149). l l l ] l -J J J J J Table 3. Surface areas by habitat type within the middle Susitna River expressed as a percentage of the total criver corridor area. Percenta~e by Dlschar~e Habitat Type 5,100 cfs 7,400 cfs 10,600 cfs 12,500 cfs 16,000 cts 18,000 cts Mainstem 31 .2 32.2 35.1 36.7 39.7 43.3 Side Channel 9.8 10.6 12.5 14.1 15.4 12.4 Side Slough 1.5 1.8 1.7 1.5 1.1 1.5 Upland Slough 0.2 0.3 0.2 0.3 0.3 0.3 Tributary Mouth 0.2 0.2 0.2 0.3 0.3 0.2 Gravel Bar 32.1 28.5 23.5 22.2 17.9 16.3 Vegetated Bar 24.9 26.5 26.4 24.7 25.3 25.9 23,000 cfs 49.1 16.3 0.7 0.3 0.2 10.7 22.6 .; ... -12- Table4. Percent change In digitized surface areas relative to corresponding areas present at 23,000 cfs. Percenta~e Change by Discharge Habitat Type 18,000 cfs 16,000 cfs 12,500 cfs 10,600 cfs 7.400 cfs 5,100 cfs Main stem -11.3 -15.5 -23.7 -25.4 -30.6 -34.4 Side Channel -23.3 -1.5 -11.7 -20.8 -31 .2 -38.1 Side Slough 121.1 62.8 124.1 155.8 176.3 125.4 Upland Slough 0.8 -7.4 -9.8 -11.9 -14.8 -32.8 Tributary Mouth 52.1 109.1 116.5 53.7 28.1 28.9 Gravel Bar 53.2 74.0 111 .8 127.1 181 .9 209.3 60 "' ~ .q: Q) 0 -t: :::J (/) .... 40 0 -o .... .... 0 u .... Q) > a: ~ 20 ~ -c: Q) l: 10 Q) c.. 60 ca ~ < Cll 0 ca 't: :::J (/) ... 40 0 "t:l 1: 0 u ... Cll > ii: ca 20 ~ ..... c: Cll ~ 10 Cll c.. FIgure 5. Talkeetna-to-Lane Creek AM 101 to 113 MAINSTEM SIDE SLOUGH 5 10 15 20 -3 Mainstem Discharge at Gold Creek (x10 cfs) Lane Creek-to-Curry AM 113 to 122 5 10 15 -3 Mainstem Discharge at Gold Creek (x10 cfs) "' ~ .q: Q) 0 "' 't: :::J (/) .... 0 -o .... .... 0 u .... Q) > a: "' ~ c Q) l: Q) c.. ca ~ < Cll 0 ca 't: :::J (/) ... 0 "t:l -.:: ... 0 u ... Cll > ii: ca ~ ..... c: Cll ~ Cll c.. 60 50 40 30 20 10 60 50 40 30 20 10 Curry-to-Gold Creek AM 122 to 138 SIDE SLOUGH • 5 10 15 20 -3 Mainstem Discharge at Gold Creek (x10 cfs) Gold Creek-to-Devil Canyon AM 138 to 149 SIDE CHANNEL SIDE SLOUGH 5 10 15 20 -3 Mainstem Discharge at Gold Creek (x10 cfs) Surface area responses -to mains-tern discharge expressed as a percentage of the -total river corridor surface area wi-thin each of four river subsegments. -13- Talkeetna to Devil Canyon RM 101 to 149 Talkeetna to Lane Creek RM 101 to 113 Lane Creek to Curry RM 113 to 122 Curry to Gold Creek RM 122 to 138 Gold Creek to Devil Canyon RM 138 to 149 5100 Figure 6. Discharge (cfs) 7400 10,600 12,500 16,000 18,000 23,000 A comparison of relative amounts of the different habitat types comprising various subsegments of the Susitna River at seven mainstem discharges. -14- Main stem D Side Channel Side Slough Gravel Bar Vegetated Bar DISCUSSION Air photo interpretation Is highly dependent upon the quality of the photography. AI though each set of photographs obtaI ned for thIs study was generally clear and complete, the time of day, date, and prevail lng weather conditions at the time the aerial photographic missions were flown affected the extent to which detailed riverine features were visible. The 23,000 cfs photography, taken on June 1, 1982, was obtained at a time of the year when the sun was at a high angle and decidlous vegetation had not fully leafed-out. This resulted in few shadows, enabling excellent del ineatlon of water's edge and slough boundaries. The 7,400 cfs and 5,100 cfs photography, obtained on October 4 and 14, 1984, respectively, have extensive areas of shadows along the south and east shorelines. This was due primarily to the tow sun angle during that time of year. These shadows sometimes obscured the water's edge and made some surface area del lneations more difficult. The remaining sets of photography had Isolated shadow problems. In spite of the minor prob I ems wIth photographic deta II, accurate and rei I ab I e surface area measurements were obtained using various techniques to aid In de I I neat Ions. The 9,000 cfs photography, taken on October 8, 1983, was suspected of providing somewhat erroneous surface area measurements because of prevailing snow and river Ice conditions. Malnstem and side channel surface area measurements obtained from the 9,000 cfs photography underestimated total surface area because of the Influence of shore Ice -15- which reduced wetted top width. Side slough habitat at 9,000 cfs was over est I mated In 1983 because the sharp contrast between snow and wet sand made it extremely difficult to accurately define the water's edge. Tributary mouth habitat was underestimated In 1983 because of the difficulty In distinguishing between the clearwater plume of the tributary and the clearing malnstem. Because of these problems with the 9,000 cfs photography and the discrepancies in the surface area data when compared to the 10,600 and 7,400 cfs data, the 9,000 cfs photography and data were not Included In this analysis. Aquatic habitat surface area responses are a function of streamflow and channel geometry. Localized channel geometry changes were observed between the 18,000 cfs photography obtained In 1980 and the remaining sIx sets of photography taken in 1982-84 (K I I nger-K I ngs I ey and Tr i hey 1985). These appeared to have been the result of high flow events which occurred during July and August 1981. The apparently Inconsistent surface area measurements for side channel and side slough habitat types at 18,000 cfs can be explained as a result of scouring which occurred during this period. Closer examination of the 18,000 cfs data shows a difference of approximately +40 acres between the amount of side slough surface area present on the 18,000 cfs photos versus the amount expected by Interpolation between 16,000 and 23,000 cfs. Conversely, a difference of approxl mate I y -280 acres is apparent between observed and expected surface area values for side channel habitat at 18,000 cfs. The scouring out of channels could be expected to have resulted in habitat transformations from side slough to side channels at locations where DISCUSSION Air photo interpretation Is highly dependent upon the quality of the photography. AI though each set of photographs obtaI ned for this study was generally clear and complete, the time of day, date, and prevail lng weather conditions at the time the aerial photographic missions were flown affected the extent to which detailed riverine features were visible. The 23,000 cfs photography, taken on June 1, 1982, was obtained at a time of the year when the sun was at a high angle and decidlous vegetation had not fully leafed-out. This resulted in few shadows, enabling excellent del ineatlon of water's edge and slough boundaries. The 7,400 cfs and 5,100 cfs photography, obtained on October 4 and 14, 1984, respectively, have extensive areas of shadows along the south and east shorelines. This was due primarily to the low sun angle during that time of year. These shadows sometimes obscured the water's edge and made some surface area delineations more difficult. The remaining sets of photography had Isolated shadow problems. In spite of the minor prob I ems wIth photographic deta II, accurate and rei I able surface area measurements were obtained using various techniques to aid in del lneatlons. The 9,000 cfs photography, taken on October 8, 1983, was suspected of providing somewhat erroneous surface area measurements because of preva II I ng snow and rIver Ice condItIons. Ma I nstem and sIde channe I surface area measurements obtained from the 9,000 cfs photography underestimated total surface area because of the Influence of shore Ice -15- which reduced wetted top w ldth. Side slough habitat at 9,000 cfs was everest I mated In 1983 because the sharp contrast between snow and wet sand made it extremely difficult to accurately define the water's edge. Tributary mouth habitat was underestimated In 1983 because of the difficulty In distinguishing between the clearwater plume of the tributary and the clearing malnstem. Because of these problems with the 9,000 cfs photography and the discrepancies in the surface area data when compared to the 10,600 and 7,400 cfs data, the 9,000 cfs photography and data were not Included In this analysis. Aquatic habitat surface area responses are a function of streamflow and channe I geometry. Loca I I zed channe I geometry changes were observed between the 18,000 cfs photography obtained in 1980 and the remaining sIx sets of photography taken in 1982-84 (K I i nger-K I ngs I ey and Tr i hey 1985). These appeared to have been the result of high flow events which occurred during July and August 1981. The apparently Inconsistent surface area measurements for side channel and side slough habitat types at 18,000 cfs can be explained as a result of scouring which occurred during this period. Closer examination of the 18,000 cfs data shows a difference of approximately +40 acres between the amount of side slough surface area present on the 18,000 cfs photos versus the amount expected by Interpolation between 16,000 and 23,000 cfs. Conversely, a difference of approximately -280 acres is apparent between observed and expected surface area values for side channel habitat at 18,000 cfs. The scouring out of channels could be expected to have resulted in habitat transformations from side slough to side channels at locations where head berms were lowered. These transformations could account for the 40 acres of side slough surface area apparently lost. The additional 240 acres of side channel surface area beyond that gained due to habitat transformation from side slough may be a result of lateral cutting of the banks of the channels. This lateral cutting would result in a wider channel and, therefore, a greater surface area for a given length of channel. Channel morphology changes and habitat transformations are considered a normal occurrence when viewed In the context of long term channel behavior. Studies conducted on braided glacial rivers in New Zealand (Mosley 1982, 1983) Indicate that multi-channel river systems typical Jy provide a relatively constant amount of habitat despite the frequent morphological changes the river experiences. The channel changes and accompanying habitat transformations represent a relatively smal I percentage of the total wetted surface area of the middle Susltna River. At 23,000 cfs, approximately 5,000 acres of wetted area Is present. The 40 acres of side slough habitat which was transformed into side channel habitat represents 0.8 percent of that total wetted area. The additional side channel habitat gained as a result of lateral channel bank cutting or other similar processes represents approximately 4.8 percent of the total wetted surface area. The magnItude of channe I changes expected to occur durIng years exhibiting more typical flow regimes would be expected to be Jess than these. -16- Definitions for aquatic habitat types used In this study represent a set of visually recognizable, environmental characteristics that do not restrict the occurrence of a particular habitat type to fixed geographical locations. An example of the flow-dependent nature of these definitions and how habitat transformations may occur is reflected by side slough and side channel habitats. Side sloughs, by definition, are clear water habitats In which the flow Is maintained by upwelling and local surface runoff. A non-vegetated alI uvial berm at the upstream end of the dewatered overflow channel separates the clear water habitat from the active channel. When malnstem discharge Increases and river stage rises, the alI uvial berm at the head of the slough is overtopped. Turbid malnstem water f.lows Into the channel and replaces the former c I ear water habitat with deeper, faster-f I owIng turbid water. The aquatic habitat at this location then fits the definition of side chan ne I habitat. Con verse I y, as m a I nstem dIscharge decreases, areas classified as side channels may become cut off from mainstem flow at their upstream end and become clear water habitats. If the clear water inflow to these systems is sufficient to maintain a downstream connection with the mainstem, these areas fit the definition of side slough habitat. General trends In surface area response to malnstem discharge became apparent In this study. As malnstem discharge decreased, the surface area of both malnstem and side channel habitat types decreased. Concurrently, side slough habitat surface area Increased with decreasing discharge. The decrease In side slough surface area shown at 5,100 cfs was due to some of the sloughs dewatering at their downstream end leaving remnant, ponded water which was not considered available habitat. The surface area response of malnstem, side channel, and side slough habitats Is not necessarily directly correlated with habitat quality, nor does it directly reflect the amount of usable habitat available. For example, In mainstem and some side channel habitats, velocity and depth may be I lmlting factors for the distribution of fish. As malnstem and side channel surface areas decrease with decreasing mainstem stage, water depths and velocities In these areas are reduced, possibly making these habitats more suitable for use by fish. Cenversely, as malnstem discharge decreases and side slough habitat surface area increases, these already shallow slough areas may become even shallower with very low velocities. Access Into these areas may become a problem and/or the shallow depths of the sloughs themselves may result In less than suitable habitat. Trends In surface area response for tributary mouth habitat were such that surface area was lowest at a malnstem discharge of 23,000 cfs, hIghest at moderate rna I nstem discharges and decreased at discharges of 10,600 cfs and below. At 23,000 cfs, the combination of high malnstem stage and water velocities resulted In a shearing off of the clear water plume as it entered the malnstem. Tributary mouth habitat surface area is a function of both malnstem discharge and tributary flow. The decrease In tributary mouth surface area at the lower malnstem discharges probably reflects tower tributary flows. The 5,100 and 7,400 cfs photos were taken In October when tributary flows are very low. -17- Upland slough surface area remained relatively constant over the range of malnstem discharges Investigated. At 5,100 cfs, the low surface area was due to some upland sloughs becoming dewatered at their mouths leaving the sloughs as remnant, ponded areas Inaccessible to fish. At lower malnstem discharges, the combined surface area of clear water habitats was greater than at higher malnstem discharges. For example, a reduction in malnstem discharge from 23,000 to 10,600 cfs (essentially halving the mid-summer flow) results In a 200 percent Increase In total clear water surface area with a 50 percent decrease in turbid water surface area, and a 125 percent Increase In exposed gravel bars. Even a decrease in discharge from 23,000 to 16,000 cfs results in a 170 percent increase In clear water, prlmarl ly due to Increased tributary mouth surface area. This Increase In clear water may be Important for primary and secondary production If these clear water areas remain relatively stable. It must be re-emphasized here that an Increase In clear water surface area Is not directly correlated with an Increase in suitable fish habitat. Upwelling and intragravel flow have been recognized as strongly influencing the spawning behavior of chum and sockeye salmon In Alaska (Estes and Vincent-Lang 1984). By definition, side sloughs are clear water areas maintained by upwelling. Without field verification, It is difficult to distinguish between true side sloughs and areas containing clear water due to settling out of suspended sediments and possibly dilution by surface water runoff once the upstream berm of a side channel Is dewatered. Different subsegments of the middle Susltna River have different morphology and vary In the relative amounts of wetted areas, gravel bars, and vegetated Islands. In all subsegments, malnstem and vegetated island surface areas predominate. The greatest diversity occurs in the Lane Creek-to-Gold Creek subsegment (RM 113 to 138), In which a greater percentage of the total surface area Is represented by gravel and vegetated bars. This river subsegment is characterized by a more braided channel pattern. In these areas, the relatively large edge effect due to the numerous Islands and gravel bars may result in the greatest potential for creation of more usable habitat along channel margins and In channels with higher streambed elevations as malnstem stage drops and water velocities are reduced. In contrast, the relatively steep-banked, channelized areas of the river where edge effects are minimal, such as from RM 102 to 113, will probably not show as large an Increase In potential habitat. The results of this study can be used to Indicate the potential for Increase or decrease In the amount of usable habitat by evaluating surface area responses of various habitat types during the open water season and w lth existing channel geometry. The term usable habitat would Include not only fish habitat, but also aquatic habitats suitable for primary and secondary production. However, the limitations of the surface area data generated by this study must be realized. These I imitations reflect the strictly physical descriptions of the habitat types defIned here. -18- The results of this study, however, can be applied to both ongoing and future studies which focus more directly on various biological features of aquatl c habitats. HabItat reconnaIssance work done by Aaserude, et al. (1985) focused on further defining and subdividing habitat types Into categories which more specifically define habitat attributes and responses to flow. Fish uti I lzatlon data (Hoffman 1985) wll I be appl led to the results of the habitat reconnaissance work to provide a measure of the suitability of the various aquatic habitats for use by adult and juven i I e sa I mon. Measurements of primary production in the middle river are anticipated from AEIDC. This work, in combination with the development of a euphotic surface area response model (Reub, et al. 1985), will address the issue of with-project primary production potential. These studies wll I provide biological significance to the increase In total surface area of clear water habitats seen in this study as mainstem discharge decreased. REFERENCES Aaserude, R.J., J. Thiele, and D. Trudgen. 1985. Categorization and characterization of aquatic habitat types of the middle Susltna River. E. Woody Trihey and Associates. Anchorage, AK. Technical memorandum. 1 vol. Acres American Inc. 1983. Susltna hydroelectric project FERC I icense appl !cation, Exhibit E, Chapter 2, Anchorage, AK. Alaska Department of Fish and Game, Susitna Hydro Aquatic Studies. 1983. Phase I I bas I c d at a report. V o I • 4 : Aq u at I c h a b i tat an d i n s t rea m flow studies, 1982. Anchorage, AK. Part 1, p. 2. Bredthauer, S., and· B. Drage. 1982. Alaska Power Authority, Susltna hydroelectric project; task 3-hydrology; river morphology. R&M Consultants, Inc., Anchorage, AK. Report for Acres American Inc. Estes, C.C., and D.S. Vincent-Lang, eds. 1984. Report No. 3. Aquatic habitat and instream flow Investigations (May-October 1983). Chapter 7: An evaluation of chum and sockeye salmon spawning habitat In sloughs and side channels of the middle Susltna River. Susltna Hydro Aquatic Studies, Alaska Dept. of Fish and Game. Report for AI aska Power Authority, Anchorage, AK. Document 1936. 1 vo I. Hoffman, A. G. 1985. Report No. 9. Summary of sa I mon fIshery data for selected middle Susitna River sites. Susitna Hydro Aquatic Studies, Alaska Dept. of Fish and Game. Report for Alaska Power Authority, Anchorage, AK. 1 vol. Klinger, S. 1985. Analysis of middle Susltna River aerial photography and determination of aquatic habitat type surface areas. E. Woody Trihey and Associates. Anchorage, AK. Technical memorandum. 6 pp. -19- Klinger, S., and W. Trlhey. 1984. Response of aquatic habitat surface areas to malnstem discharge in the Talkeetna-to-Devil Canyon reach of the Sus I tna River, AI ask a. E. Woody Tr i hey and Associates. Report for Alaska Power Authority. Susltna Hydroelectric Project. Document 1693. 1 vol. Kl inger-Kingsley, S.A., and E.W. Trlhey. 1985. Reconci llation of surface area measurements in the 1980 and 1984 aerial photography of the middle Susltna River resulting from local !zed changes in channel morpho I ogy. E. Woody Tr i hey & AssocIates. Anchorage, AK. Technical memorandum. 1 vol. Mosley, M.P. 1982. Analysis of the effect of changing discharge on channel morphology and instream uses In a braided river, Ohau River New Zealand. Water Resources Research 18(4): 800-812. ___ • 1983. Response of braided rivers to changing discharge. Journal of Hydrology 22:(1) 18-67. Reub, G., E.W. Trlhey, and C. Wilkinson. 1985. Preliminary analysis of the influence of altered middle river discharge and turbidity regimes on the surface area of the euphotic zone. E. Woody Trihey and Associates. Anchorage, AK. Technical memorandum. vol. Scu II y, D.R., L.S. Leveen, and R.S. George. 1978. Surface water records of Cook Inlet Basin, Alaska, through September 1975. U.S. Geological Survey, Anchorage, AK. Open-file Report 78-498. 102 pp. Steward Ill, C.R., R.C. Wilkinson, and A. Milner. 1985. Response of juvenile chinook habitat to malnstem discharge In the Talkeetna-to- Devil Canyon segment of the Susltna River, Alaska. Trihey and Associates. Report for Alaska Power Authority, Anchorage, AK. vol. University of Alaska-Fairbanks, Arctic Environmental Information and Data Center. 1985. Geomorphic change in the middle Susltna River since 1949. Report tor Alaska Power Authority. Susltna Hydroelectric Project. 53 pp. U.S. Geological Survey. 1972. Rating table tor Susltna River at Gold Creek, Alaska from October 1, 1967 to 1972. Unpublished data. U.S. Geological Survey. 1982. Rating table tor Susltna River at Gold Creek, Alaska from October 1, 1981 to 1982. Unpubl !shed data. -20- Appendix 1. Aerial photographs of the middle Susltna River. Aquatic habitat types are del lneated at seven malnstem discharges. Prominent topographic features and study sites are Identified. LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY PLATE 1 OF 18 RIVERMILE 147 TO 149 + RIVER MILE 23,000 cfs 1 '1 = 1000 ' 1 ":::: 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'ihey& IJ:{]£00,?6£c §!])&,~@@ Associates 1\qua!c Resa.«ee SUS ITNA JOI NT VE N TUR E Speoaisls LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTA RY MOUTH T TRIBUTAR Y + RIVER M ILE PLATE 1 OF 18 RIVERMILE 147 TO 149 'I '; j~! • • f" i , .. ~., / . 't ·: ' , . ~ "·' ; ",;.,·· .• r• PORTAGE CREEK TM 1 " 1000 ' ALASKA POWER AUTHO RITY SUSITNA HYDROELECTRIC P ROJECT ~ 'll'ihey& [){]£00 ~£,§00£~@ Ass ociates Aquauc Reso.iCe peoalost SU SI TNA JO I NT VE NT URE I :~.'.! LEGEND MS MAINSTE M SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MIL E PLATE 1 OF 18 RIVERMILE 147TO 149 1 ,, :::: 1000' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ li'ihey& IXl&lru~&d~liD&~©@ Associates Aqua he Rese t lfCe SUSITNA JO I NT VENTURE Speoalsts LEGEND MS MAIN STEM SC SIDE CHANN EL SS SIDE SLOUG H US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDD L E SUSITNA RI VER T TRIBU TARY PLATE 2 OF 18 AI VERMI LE 144 TO 146 + RIVER MIL E 23,0 0 0 cfs 1" =: 1000 I ALASKA POWER AU THO RITY SUSITNA HYDROELECTRIC PROJECT ~~her& [}(l£ffil~£o ~£®@ @ Auociiltes '"!Jd:.c Resou ce SUSITNA JOI N VENTURE Soeoalslo LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM T R IB UTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MILE. PLATE 1 OF 18 RIVERMI LE 147 TO 149 = 1000 ' 1 tf 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 11-ihey& OO&lfl ~L(.·, G'it .J\/·rf:rl .' Associates AQ1 :.1~('. F~\?S~)Il 'L. S U S iT ~A JOI<\~ 'h NT U RE S ~x;::-...1 '>(" LEG END MS MAIN STEM SC SIDE C HANNEL SS SIDE SLOUGH US UPLAND SLOUGH M IDDL E SU SITN A RI VE R TM T RIBUTARY MOUTH T TRIBUTARY + RIVER MILE PL ATE 2 OF 18 RIVERMILE 144 TO 14 6 == 1000' ALASKA P OWER AUTHO R IT Y S US IT NA HYDROELECTRIC PROJECT ~ Trihey& [J{]&OOZ?-&,§[;3&®©© Auociai!J!I __ .;c, . • S :~n ., SUSITNA JO I NT VENTU RE L EGEND MS MAINSTEM SC SIDE CHANNEL SS Sl DE SLOUGH US UPLAND SLOUGH + 144 TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE ,x, ·~~:· .. ~ _, ~'' ~ ~ ,.,r \. " ~~· r; .. ~.··· ... 'J ~• • • • r .... ' I~ j :~ •• ~ ~~ I ~lltoi ,. ' : -· ~ , If ~ ... • • , J ' • 'S "', f' ..... •. ,. .,... • !. , .. ' .: Ci MIDDLE SUSITNA RI VER PLATE 2 OF 18 R IVER MILE 14 4 TO 146 SLOUGH 21A SLOUGH 21A 1 " -100 I ALASKA PO WER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ~ihey& ():(]£00~£" ~00£~@ Asaocllltes A.oua~ Reso. :<ce SUSITNA JOINT VENTU RE S!S • + 141 LEGEND M S MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MI LE MI DDLE SUSITNA RIVER PLATE 3 OF 18 RI VERMILE 141 TO 144 • 2 3,00 0 cfs "\"" ., 1" ...;... __ ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'ihey& (){]£00zg& .. ~®&~@@ Associates Aqua!«: Resource SUSITNA JOINT VtN TURE Speoaits!S LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 3 OF 18 RIVERMILE 141 TO 144 1" 1000' •• ~ ~-,_ . 1 '' 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ Trihey& 00&~2LL · b:: .; .. ; ... ._. : .. ·_ ... Assoeiates 1\.J,,,JIIC" fll ..::;l-llltCC' SUS :l NA Jul<": ·v t_{\!1 l.._i R ~ ~~~n u:T1:.:· LEGE N D MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITN .A RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 3 OF 18 RIVERMILE 141 TO 144 ALASKA POWER AUTHORITY SUS I TNA HYDROE L ECTRIC PROJECT -~~& ~-~ Associ- Aq.oatiC Resoc•ce SUSITNA JOINT VENTURE Speaaists LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MILE F ATE 3 OF 18 RIVERMILE 141 TO 144 ALAS KA POWER A UTHO R ITY SUSITNA HYDROELECTRIC PROJECT • ~hey& ~a~ Assoc:l- Aqua!<: Resot..fal SUSITNA JOINT VENTURE Specia'1Sis LEGEN D MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIB UTARY + RIVER MILE • SLOUGH 20 WATERFALL CREEK M IDDLE SUSITNA RIVE R PLATE 4 OF 18 RI VER MI LE 139 TO 141 23,000 cfs 1" = 1000' + 141 1 " = 10 00 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ "'l'lhey& [){]£00~&·· ~liD&®©@ Associates Aquatc Resource SUSITNA JO IN T V ENTU R E Speaal LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 4 OF 18 RIVERMILE 139 TO 141 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTR I C PROJECT ~ ll'ihey& 1}{]£00~& "~®~~"'@@ Associates A~~l~ICi:fet~l ~r~-z, Speca6tc. SUSITNA JOII'..:< VENTURE LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH Ml DOLE SUSITNA RIVER T TRIBUTARY + RIVER MILE PLATE 4 OF 18 RIVERMILE 139 TO 141 1 ~ ::Z 1000 I A LAS K A PO WER AUTHO RITY SUSI TNA H YDROELECTRIC PROJECT ~ ll'ihey& [}{JftlOO~&. g ~®M©@ A ssociates Aquarc Resource SUSITNA JO I NT VENTURE Speoalists L EGEND MS MAINSTEM SC SIDE C H ANNEL SS SIDE SL OUGH US UPLAN D SLOUGH MI DDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 4 OF 18 RIVERMILE 139 TO 141 A LAS KA POWER AU THORITY SUSITNA HYDROELECTRIC PROJECT • ~hey· IXI£MIA\•Ii!JUCa) Associates Aquattc Resol.;m ' SUSITNA JOINT VENTURE Speoalsts sc -- sc LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE S L OUGH US UPLAND SLOUGH - TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE SLOUGH 13 • . + 136 1" = 1000' ALAS KA POWER AUTHORITY MIDDLE SUSITNA RIVER SUS ITNA HYDROELECTR I C PROJECT ~ 11-lhey& IXI&!ru~&" l!:OO&~@ Associates Aquaoc Resot.t ce SUSIT NA JOI NT V ENTU RE SpeaalsiS PLATE 5 OF 18 RIVERMILE 136 TO 138 23,000 cfs LEGEN D MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MID DL E SUSITNA RIVER PLATE 5 OF 18 RIVERMILE 136 TO 138 1 tl 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'ihey& 000:.00~&.·· @rf\~©©© Associates ·\o.k11JC ResOUr e SUSITNA ~OINT VENTuRE Spec , LEGEND MS M AINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RI VER T TRIBUTARY + RIVER MILE PLATE 5 OF 18 RIVERMILE 136 TO 138 ALASKA POWER A UTHORITY SUSITNA HYDROELECTRIC PROJECT • ~hey & ~-~ "-oct-• Aquatic ReSCJU(ce SUSITNA JOINT VENTURE SpecieJ!sts L EGEN D MS MAI NS TEM SC SIDE CHA NNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITN A RIV E R TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PL ATE 5 OF 18 RIVER MILE 136 TO 138 ALASKA POWER AUTHORITY SUSIT NA HYDROELECTRIC PROJECT -~~· llG£00~£ .. ~ Associates AquatiC Res01•ce SUSITNA JOINT VENTURE Speciaists lEGEND MS MAINSTEM SC SIDE CHANNEL SS S I DE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE / ., ·""' . ~ Ml DOLE SUS ITN A RIV ER PLATE 6 OF 18 RIVERMILE 133 TO 13 6 23,000 c fs + 136 1 " = 1000 ' 1 " = 1000 ' ALASK A P OW ER AUTH O RITY SUSITNA HYDROELECTRIC PROJECT ~ 11'ihey& [){]£00~&<> ~00&®©@ Associates AquatiC Resource SUSITNA JOI N T VE NTUR E Speaalists LEGE ND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 6 OF 18 RIVERMILE 133 TO 136 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT· ~ ll'ihey& 00/A\00~£ D ~00£~@ Associates Aq ~ate Resou<ce SUSITNA JOINT VENTURE Speoaists LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH M I DDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 6 OF 18 RIVERMILE 13 3 TO 136 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'lhey& 00£00~Li:l " !!®£~© ,._.... Aquatc Reso.-rc · SUSITNA JO i fi;T VENTURE Speaal"·' LEGEND MS MAINSTE M SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH M IDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 6 OF 18 RIVERMILE 133 TO 136 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT .ll'lhey& OOI.i.\OOW,t\ .. ~ Assoclaus Aquat;c Resource SUSITNA JOINT VENTURE SpectalstS LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MILE PlATE 7 OF 18 RIVERMilE 130 TO 132 23,000 cfs A LASKA PO WE R AUTHORITY SUSITNA HYDROELECTRIC PROJECT • '111hey& ~8/.i.\a[!~ Auocl-'es Aquatic Resource SUSITNA JOINT VENTURE Speoalsts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 7 OF 18 RIVERMILE 130 TO 132 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ '11-lhey& 00£00;g£a[!~ Associates Aqua~1c Resourco SUSITNA JOINT VENTURE Speoa~s:s / / LEGEND MS MAINSTEM SC SIDE CHANNEL SS SID E SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRlBUTARY + RIVER MILE PLATE 7 OF 18 RIVERMILE 130 TO 132 ~·;;. ,. -" + 132 1000 ' / ALASKA POWER AUTHORITY SUSITNA HYDROE L ECTRIC PROJECT ~ Trihey& !Xl&00 ?6 &, [f~)_%~.~~0.: Associates Aq, ~.l~:l R~~~ ,,(.\'\ SUS I i"N A JOiNC \itNTURE PCOdHS1~ LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 7 OF 18 RIVEAMILE 130 TO 132 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~~& ~~--~l~k'@ t=~rce SpeaaiS!s SUSITNA JOIN r Vt NTU R F LEGEND MS MA IN STEM SC SI D E CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTAR Y MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 8 OF 18 RIVERMILE 127 TO 129 23,000 cfs = 1000' .... + 12 9 1" ·rooo · ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~~~& !lM.\OO~lt\'• &!tl~~@ ~~~:x.rec SiJCOd\ •s SUSI TNA J OI N ~ VENTUR E LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 8 OF 18 RIVERMILE 127 TO 129 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ll'lhay& [}{J£00~£" ~l!i&~@ Aasoc:iates Aquanc Rcscurce SUSITr-.A JOINT VEr-.TURE Speoalst:; LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 8 OF 18 RIVERMILE 127 TO 129 ALASKA POWER AUTH O RITY SUSITNA HYDROELECTRIC PROJECT ~ Trih~>y& [)(]&00~&, @j[ID£@@@ Associates Aci<n<e Rescurce SU SI TNA JOINT VE:NT U RE Speor.l!1 SIS LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE Ml DOLE SUSITNA RIVE R PL ATE 8 OF 18 RIVER MILE 127 TO 129 ALASKA POW ER AUT HORITY SUSITNA HYDROELECTRIC PROJECT • 11ihey& ~·IDUCO Associ- AquatiC Resource SUSITNA. JOINT VENTURE Speaal1 s1S FIFTH OF JULY CREE K OR BLACK BEAR • C RE E K LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH .. TM TRIBUTARY MOUTH M I DDLE SUSITNA RIVER T TRIBUTARY PLATE 9 OF 18 RIVERMILE 124 TO 126 + RIVER MILE 23,000 cfs SLOUGH B 1, 1000' 1 " -· 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ll'ihey& 00~00~£" ~~~'o!:.~i©© Associates ·'4..11 . Rt'SOI•ce SUSi INA JOIN I VE N TU Af. SiJCOilbts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MI DDL E S USIT N A RIVER PLATE 9 OF 18 RIVERMILE 124 TO 126 ALASKA PO W ER AUTH O RITY SUSITNA HYDROELECTRIC PROJECT ~~~· 00£00~£"' ~®£~@ Associates Aquatc RP.SOU<ce SUSITNA JOINT VENTURE Speciails!s LEG END MS M AIN STEM SC SIDE CHANNEL SS SID E SLOUGH US UP L AND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 9 OF 18 RIVERMILE 124 TO 126 + 126 1 ., = 1000' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ll'ihey& [l{]£~t2£o~[ID£~@ Associates ~ResoLJ~ce SUSITNA JOINT VENTURE LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 9 OF 18 RIVERMILE 124 TO 126 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~~they& (J{l£00~& ~ ~00£§©@ Associates AqJatc Resource SUSITNA JOINT VENTURE Speaal s LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SL OUGH • .. . . "'- TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE . ~. •. 1..' _,,. ', ~ ~ , .. •".j' . -··- .; 1 " 1000 1 ALASKA POWER AUTHORITY MIDDLE SUSITNA RIVER SUSITNA HYDROELECTRIC PROJECT ~ ltihey& []{]£00~£o§[ID~@ Associortes ~esot!fce SUSI TNA JO IN T V ENTURE PLAT E 10 OF 18 RIVERMILE 122 TO 124 23,000 cfs . . LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE •".! .. r -· ., ... ; ..... •• 4 .. -~ • '<oo .... .. MIDDLE SUSITNA RIVER -• ,.,_:: .. • .. -, ...... " .""\a~ .. , "' • . .._ r;. ""'t' -. ... 'A 4 . '~ s + 123 PLATE 10 OF 18 RIVERMILE 122 TO 124 1 I' --1000 I 1 " = 1000 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ Trihey& [){]£rnl~&, §@&~©© Associates Aqua:C Resot l1Ce SUS rT NA JOINT V ENT U RE S;ocoaist LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH M ID DLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE P LAT E 10 OF 18 RIVERMILE 122 TO 124 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ~lhey& l}{]£00l6&" ~[ID~@@ Associates Aqua1~ SU SI T N A JOI NT V ENTU RE Speaal s LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH ( ssf ~u s TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE -... .,._'1- , ;-',t • • MIDDLE SUSITNA RIVER PLATE 10 OF 18 RIVERMILE 122 TO 124 1" 1000 ' ,.. / ... 1 " 10 00 ' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ Trihey& !)\]&00~&'" ~li1i!.\~©I.Q) Associates f..qllatoc Resource SUS I TN A JO IN 'T liE:NTU R E Speoaosts /sc LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM T RI BUTARY MOUTH T TRIBUTARY + RIVER MILE A L ASKA PO W ER AUTHORITY MIDDLE SUSITNA RIVER SUSITNA HYDROELECTRIC PROJECT ~ ~IIIey& ~?l£a~ Auoclaotes Aquatic Resource SUSITNA JOINT VENTURE Speaalsls PLATE 11 OF 18 RIVER MILE 119 TO 121 23,000 cfs L EG END MS MAI NSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLA ND SLOUGH TM TRIBUTARY MOUTH T TR IBUTARY + RIVER MILE ... ... MIDDLE SUSITNA RI VER PLATE 11 OF 18 RIVERMILE 119 TO 121 MS sc + 121 "" sc - ALASKA POWER AUT HO RITY SUSITNA HYDROELECTRIC PROJECT ~ '1Hhey& ll0£00~£ a {j{ll&~ Associates AquatiC Resource SUSITNA JOINT VENTURE Speaahsts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE ::.~_· ~~:--::...~ ... ' ~ . . , •-- MIDDLE SUSITNA RIVER PLATE 11 OF 18 RIVERMILE 119 TO 121 ... ~ . . " ALASKA POWER AUT H ORITY SUSITNA HYDROE L ECTRIC PROJECT ~ ll'lhey& IXJLt.\OO?l£a ~[!l~ Assocl.ws AQucit,c Resource SUSITNA JOINT VENTURE SpedaliSts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUT H MID DL E SU SIT NA RIVER T TRIBUTARY + RIVER MILE PLATE 11 OF 18 RIVERMILE 119 TO 121 A LAS KA PO WER AUTHORITY SUSITNA H Y DROE L ECTRIC PROJ ECT ~~hey& 00£1PJ1l£a~~ Assoel81es AquatiC Resource SUSITNA JOINT VENTURE Speoailsts LEGEND MS sc ss us MAINSTEM SIDE CHANNEL SIDE SLOUGH UPLAND SLOUGH TM T + TRIBUTARY M OUTH TRIBUTARY RIVER MILE M IDDLE SUSITNA RIVER PLATE 12 OF 18 RIVERMILE 116 TO 118 23,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ••hey& ~~0~ Aseoclates AqJatiC Resource SUSITNA JOINT VENTURE Speciaists L EG END MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOU GH US UPLAND SLOUGH TM TRIBUTARY MOUTH M I DD LE SUSITNA RIVER T TRIBUTARY + RIVER MILE PLATE 12 OF 18 RIVE RMILE 116 TO 118 1 " = 1000' ALASKA POWE R AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'lheyl IXJ£.00~£a (j~ Asaoclllles ,C...qualte ReS()IJ{ce SUSITNA JOINT VENTURE . Spc~ts ' L EGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM T RIBUTARY MOUTH T TRIBUTARY + RIVER MIL E M IDD LE SU S ITN A RIVER PLATE 12 OF 18 RIV ERMIL E 116 TO 118 ALASKA POWER AUTHO RITY SUSITNA H Y DROELECTRIC PROJECT ~~~& OO£OO;g£o~~ Associates Aquat:c Resouce SUSITNA JOINT VENTURE Spe<:>_"'-.sts LEGEN D MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 12 OF 18 RIVERMILE 116 TO 118 ALASKA POWER AUTHOR IT Y SUSITNA HYDROELECTRIC PROJECT ~ ll'lhey& 00/A\OO~Li.\"fi~ Aaeociat .. Aquatic Resoll'ce SUSITNA JOINT VENTURE Specialsls L EGEN D MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE ~ .~. • .. .. . ....... ., , l . •·. • lo,. 4 . ~ ~.~ MIDDLE SUSITNA RIVER PLATE 13 OF 18 RIVERMILE 113 TO 115 23,000 cfs ALASKA POWER AUTHORI TY SUSITNA HYDROELECTRIC PROJECT ~ 11-lhey& IXJ£00~£o~OOL!.\~ Associates Aquaoc Resouce SUSITNA JOIN T VENTURE Speoalst s LEGEND MS MAI NSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 13 OF 18 RIVERMILE 113 TO 115 ALASKA POWER AUTHORITY SUSITNA HYDROEl ECT 1RIC PROJECT • ltlhey& ~D~ Auocl- Aquatic Resource SUSITNA JOINT VENTURE SpeoafiS!S s~ L EG END MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH + 113 TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE A LASKA PO WER AU THO RITY MIDDLE SUSITNA RIVER SUSITNA HYDROELECTRIC PROJ ECT -~hey· ~a ~ Auocl- AQuatJc Resource SUSITNA JOINT VENTURE Speciaisls PLATE 13 OF 18 RIVERMILE 113 TO 115 LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MI DDLE SUS ITN A RIV ER PLATE 13 OF 18 RIVERMILE 113 TO 115 A L ASKA POW E R AUTHORITY SU SITNA HYDROELECTRIC PROJECT • ~lhey& 00/l\lRIWA\ .. ~ Associates Aquru;cResource SUSITNA JOINT VENTURE SpeO~s + 110 LEGEND MS sc ss us MAINSTEM SIDE CHANNEL SIDE SLOUGH UPLAND SLOUGH TM T + TRIBUTARY MOUTH TRIBUTARY RIVER MILE . . ..... ·~-_ . ., .. t ... :.; ~~ ........... _ .... ..... • • • .,... • ~ .-l1 ~>- .... •• tl!_ I , ~· I ·' ... "' .. , i . . ' 't". ~. , .... ll ' •• ' -• ·.# ........ . ...,41',; • ... '(# •• ..· .... ,. ., , l \.' I • .. # --· ~ ~. ,. , f i~. , • 5 , '.to .,. ~ I ·-· ) ~l· • -~ · )t ~. MIDDLE SUSITNA RIVER PLATE 14 OF 18 RIVERMILE 110 TO 112 23,000 cfs SIDE CHANNEL 6A ·. ' . ALASKA POWER AUTHORtTY SUSITNA HYDROELECTRIC PROJECT • ~lhey& ~-~ Assocu.tes Aquatic Resourc e SUSITNA JOt NT IIENTURE SpeCiills:s LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MI DD L E S US I TNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 14 OF 18 RIVERMILE 110 TO 112 ALASKA PO WER A UTHOR ITY SUSITNA HY D ROELECTRIC PROJECT ~~hey· OO£fAIWA\a~ Assoc!Mes Aquat1c AesoL<ce SUSITNA JOINT VENTURE Special~ts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MILE PLATE 14 OF 18 RIVERMILE 110 TO 112 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 'll'lhey& ~8£o[j~ Associates Aquat:c Resource SUSITNA JOINT VENTURE Speorosts L EGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOU TH T TRIBUTA RY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 14 OF 18 RIVERMILE 110 TO 112 ALASKA POWER AUTHORITY S USITN A HYDROELECTRIC PROJECT • 111hey& Associ .... Aquatic Resource Speoalosts SUSI TNA JO I NT VENTURE LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE ,. __..-:-'-•S LOUGH 6 MIDDLE SUSITNA RIVER PLAT E 15 OF 18 RIVER M ILE 108 TO 110 2 3,000 cfs I 1" = 10 00' 1 " = 1000' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ ll'lhey& [lM\OO~a~ Associates Aquatc Rescuce SUSITNA JOINT VENTURE Speoaists LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUG H TM TRIBUTARY MOUTH T TRIBUTARY + RIVE R MILE ALASKA POWER AUTHORITY MIDDLE SU SITNA RIVER SUSITNA HYDROELECTRIC PROJECT .11-lhey& ~-~~~J£~00 =":rurce SpeoalistS SUSITNA JOINT VENTURE PLATE 15 OF 18 RIVERMILE 108 TO 110 LEGEND MS MAINST EM SC SIDE CHANNEL SS SIDE SLO UG H US UPLAND SLOUGH TM TRIBUTARY MOUTH MIDDLE SUSITNA RIVER T TRIBUTARY + RIVER MILE PLATE 15 OF 18 RIVE RMILE 108 TO 110 ALASKA PO W E R AUTHORITY SUSITNA HYDROELECTRIC PROJECT • ~hey& ~8£a ~ Asaoclates Aqua!JC Resource SUSITNA JOINT VENTURE Speaaitsts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUG H US UPLAND S LOUGH TM TRIBUTARY MOUT H T TRIBUTARY + RIV ER MI LE M I DDLE SUS ITNA RIV ER PLATE 15 OF 18 RIV ERM ILE 10 8 TO 110 A L ASKA POW ER AU T HORITY SUSITNA HY DROELECT RI C PROJECT • ~hey & ~D~ Associates Aquatic Resource SUStTNA JOt NT VENTURE Speoalsts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOU GH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 16 OF 18 RIVERMILE 105 TO 107 23,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT • ~11\er& ~-'IIIUCO "-lates AQua!<: Resource SUSITNA JOINT VENTURE Speoaisls LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOU G H US UPLAND SLOUGH TM TRI BU TARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSIT N A R I VER PL ATE 16 OF 18 RIVE RM ILE 105 TO 107 ALA S KA POWER AUTHOR I TY SUSITNA HYD ROELECTRIC PROJECT -~· ~-~ AIIIIOCi ates Aquatic Resource SUSITNA JOINT VENTURE Speciaists LEGEN D MS MAINST 'EM SC SIDE C HANN EL SS SIDE SLOUG H US UPLAND SLO UGH MIDDLE SUSITNA RIVER TM TRIBUT AR Y MOUTH T TRIBUTARY + RIVER M ILE PLATE 16 OF 18 RIVERMILE 105 TO 107 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT • lHhey& OOU1l/A\•IDUCO Aellociatea Aqua~c FiiiW:.ce SUSITNA JOINT VENTURE Speoallsts LEGEN D MS MAI NSTEM SC SIDE CHANNEL SS SIDE SL OUGH US UPL AND SLOUGH TM TRIBUTA RY MOUTH T TRIBUTAR Y + RI VER M ILE M I DDLE SU S ITN A RIVER PLATE 16 OF 18 RIV ERMILE 10 5 TO 107 A L ASKA POWER AU THORITY SUSITNA HYDROE L ECTR I C P ROJECT • ~her& ~D~ AMoclllles AquatJC Resource SU SITNA JOINT V ENTURE Specialsts LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US U PL AND SLOUGH TM TRI B UTARY MOUTH T TRIBUTARY + RIVER MILE M l DOLE SUS IT N A RI VER PLAT E 17 OF 18 RIVE RMILE 102 TO 104 23,0 0 0 cfs /sc/ 1" ALAS KA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~'ll'lhey& ~a~ AssociBIH AquatiC Resourc e SUS ITNA JOINT VENTURE Speoalists LEGEND MS MAINSTE M SC SIDE CHANNEL SS SIDE SLOUG H US UPLAN D SL O UGH sc / TM T RI B UTARY MO UTH T TRIBUT A RY + RIV ER M IL E ALASKA POWER AUTHORITY MI DDLE SUSITNA RIVER SUSITNA HYDROELECTRIC PROJECT .ll'lhey& ~-~ Assocleles Aquaiic Resource SUSITNA JOINT VENTURE Spea~IS!S PL ATE 17 O F 18 RIVE R MI LE 102 TO 104 L EGEN D MS M AIN STE M SC SI DE CH ANNE L SS SIDE SL OUG H US UP LA ND SLOUGH MIDDLE SUSIT N A R IV,ER TM TRIBUT AR Y MOU TH T TRIBUTARY + RIVER M ILE PL ATE 17 OF 18 RIV ERM ILE 102 TO 104 ALASKA PO WER A UTHO RITY SUSITNA H Y DRO EL EC T RI C PRO J ECT • 'Jiolhey& ~D~ Auoc:llltea Aquattc Resource SUSITNA JOINT VENTURE Speoal sts LEGEN D MS MA INSTE M SC SI DE CH AN NEL SS SID E SLOU GH US UPL AN D SL O UGH MIDDLE SUSITN A RIV ER TM TR I B UTARY MOUTH T T RIBUTARY + RI VER MILE PLATE 17 OF 18 RIVE RMILE 102 TO 104 ALAS KA POWER A UTHORITY SU SITNA H Y D ROELECT RIC PR OJ ECT I .1Hhey& IGAIIZ£•WA800 1 ~ce SUSITNA JOlNT VENTUM: Sped<iiSfS LEGEND M S MAINSTEM SC SIDE CHANNEL SS SIDE SLO UG H US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 18 OF 18 RIVERMIL E 101 TO 102 23,000 cfs EAST SIDE <;HANN~L . . •. ALASKA POWER AUTHORifY SUSITNA HYDROELECTRIC PROJECT .ll'lhey& Dll£IJ8WA\ •II!M\IICO Assocl81es Aquallc Resource SUSITNA JOINT VENTURE Speoalists LE GE ND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUT A RY MOUTH MIDDLE SUSITNA RIVER T T RI BUTARY + RI VE R MILE PLATE 18 OF 18 RIVERMILE 101 TO 102 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT • ll'lhey& ~ .. ~ Auoel81es Aquatic Resource SUSITNA JOINT VENTUR E Speaaists LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE MIDDLE SUSITNA RIVER PLATE 18 OF 18 RIVERMILE 101 TO 102 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT • ~hey& IIOAIIZA\•'MIUCO Auoc._ AQ.Jatic Resource SUSITNA .JOINT VENTURE Speoailsts LE GE ND MS MAIN STE M SC SIDE CHAN N EL SS SID E SLOUGH US UPLAN D SL OUGH TM TRIBUTA RY MOUTH T TRIBUTARY + RI VER M ILE M l DO L E SU SITNA RIVER PL ATE 18 O.F 18 RI VE RMI LE 101 TO 102 ALASK A PO WER A UTHO RITY SUSITNA HYDROELECTRIC PROJECT .~hey& ~ .. ~ Associates Aquai1C Resoutce SUSITNA JOINT VENTURE Specialists LEGEND MS MAINSTEM SC SIDE CHANNEL SS SIDE SLOUGH US UPLAND SLOUGH MIDDLE SUSITNA RIVER TM TRIBUTARY MOUTH T TRIBUTARY + RIVER MILE PLATE 18 OF 18 RIVERMILE 101 TO 102 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT • ~hey& IXLtaMA\•IIIJAICO Assoclallls Aquahc Resou<ce SUSITNA .IOlNT VENTURE Spea<~IStS Appendix 2. Habitat "transformation In response to changing malnstem discharge. Surface areas and breaching flows for middle Susltna River specific areas are presented. The specific areas are delineated on aerial photography taken at 23,000 cfs. In addition to surface area responding to changes In malnstem discharge, the type of habitat available In a specific area may also change In response to malnstem discharge. This flow dependent change from one habitat type to another Is referred to as "habitat transformation." One example of a habitat transformation occurs when a side channel conveying turbid water becomes a clear water side slough as the malnstem discharge (stage) recedes to a level that prevents the flow of turbid malnstem water Into the upstream entrance to the side channel and clearwater flow Is maintained in the channel by subsurface Inflow and Infiltration. Another common transformation occurs when malnstem habitat becomes side channel habitat as a result of decreasing malnstem discharge. Habitat transformations occur almost exclusively along the lateral margins of the river. Thus all wetted surface area present at 23,000 cfs which was not part of the main channel of the middle Susltna River was part 1 t 1 oned 1 nto "spec 1 f 1 c areas". These were defIned as discrete geographical locations whose physical boundaries enclose relatively homogeneous morphologic subareas of the middle Susitna River. Nearly all the wetted surface area of the specific areas at 23,000 cfs is comprised of side channel, side slough, and upland slough habitats. Large side channels or side sloughs were occasionally subdivided Into two or more specific areas based upon their channel morphology. Some portions of the mainstem <primarily shoals and upwelling areas) were also del lneated as specific areas. Each specific area was referenced to a river mile <RM) and the side of the river <looking upstream) on which It was located: left (L), right (R), or middle (M) if between two rna 1 nstem forks. Locat 1 ons of the 172 specIfIc areas are de II neated on photo plates of the 23,000 cfs aerial photography <Plates 1-18). The methodology by which habitat transformations were tracked made use of aerial photography of the middle Susltna River taken at malnstem discharges of 23,000; 18,000; 16,000; 12,500; 10,600; 9000; 7400; and 5100 cfs. At each discharge, the surface area of each specific area was measured and the habitat type the specific area respresented was determined. Eleven "habitat transformation categories" were developed to define the types of habitat transformations that a specific area might undergo as malnstem discharge declines <Aaserude et al. 1985). Habitat transformations at each specific area were Identified through photo comparison. Individual specific areas were then grouped according to the sequence of habitat transformations they underwent as mal nstem discharge decreased from 23,000 cfs to 5100 cfs <Aaserude et al. 1985). The behavior (sequence of habitat transformation) of these specific areas In response to changing malnstem discharge served as one Index by which specific areas could be described. Another useful Index by which specific areas were described and classified was breaching flow. Breaching flow Is defined as that malnstem discharge at which the head of a side channel or side slough Is overtopped by the mainstem river. Identification of habitat transformation sequence and breaching flows for Individual specific areas enabled grouping channels displaying similar characteristics into "representatIve groups"· These groups served as the toea I poInt In the analysis of habitat response to changes in malnstem discharge. Table A- 1 I lsts the malnstem discharges at which each of the specific areas becomes breached and into which representative group each specific area was grouped. Table A-2 presents surface areas for each specific area at each of the seven rna I nstem dIscharges for whIch aer I a I photography was analyzed. A detailed discussion of habitat transformations, breaching flows and their appl !cation to characterization of aquatic habitats can be found In Aaserude et al. (1985) and Steward et al. (1985). Plates 1-18. Specific areas of the middle Susitna River delineated on photography taken at a mainstem discharge of 23,000 cfs. MI DDLE S USITNA RIV ER SPEC IF IC AR EA S at 23,0 00 cfs ALASKA POWER AUTHORITY SUSITNA HYDRO ELE CTRIC PRO J ECT ~ 'll'lheylo ~OO(g~.,!!~~ AuociMIHi Aquatc Resou<ce SUSITNA JOINT VENTURE Speoalsts MIDDLE SUSITNA RIVER SPECIFIC AREAS at 23,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ -.lhey& 00!1.00i"6Li\ .. §00£~ -~-· ~esourc e SUSITNA JOINT VENTURE MIDDLE SUSITNA RIV ER SPEC IFIC AREAS at 23,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~~& IJ:Q&OO~/.t.\" 1!:00£~ _....._ I>Q.Jat'c Resource SUS I T NA JO INT VENTURE Specialsts MIDDL E SUSITNA RIV ER S PEC IF IC AREAS at 23,000 cfs ALASKA POWER AUTHOR I TY SUSITNA HYDROELECTRIC PROJECT ~~· 00/A\00~&. .. §00&~@ -~-AquaLc Resouce SUSITNA JOINT VENTURE SpeoaiS!S M IDDL E SUSITNA RIVER S PECIFIC AR EAS at 23,000 cfs ALASKA POW ER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~=:-00/.t:\OO:g £ D §@&.~ AQJOJt<: Resource SUSITNA JOINT VENTURE Spe<2 .• 1s MIDDLE SUSITNA RIVER SPECIFIC AREAS at 23,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ Trlhey& (){1&00~£ a [SOObM~@@ ~ 1\quanc Resour ce SUSITNA JO IN T VENTURE SpeoaiSIS MIDDLE SUSITNA RIVER SPECIFIC AREAS at 23,000 cfs ALASKA POWER AUTHOR I TY SUSITNA HYDROELECTRIC PROJECT ~~i~~"':" IXJIA\00;;6£ a §@Lt.\®@@ Soec.:~rilists SUSITNA JOINT VENTURE MIDDLE SUSITNA RIVER SPECIFI C AR EAS at 23,000 cfs ALASKA POW ER AUTHO RITY SUSITNA HYDRO ELECT RIC PROJECT ~~& IX!Lt.\OO?lt.'i:l " [!~~ Auoc-A<:M•hC AesoJce SUSITNA JOINT VENTURE Spoo MIDDLE SUSITN A RIV ER SPECIFIC AREAS at 23 ,000 cfs ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT ~ 111hey& oo&oo;;g&., !!:®£~@ Associ- Aquabc Resource SUSITNA JOINT VENTUR E Specialsts Tab I e A-1. Approximate breaching flows of specific areas of the middle Susitna River. Specific Breaching Representative Specific Breaching RepresentatIve Spec! tIc Breaching RepresentatIve Spec It lc Breaching RepresentatIve Area Flow (ctsl Group Area Flow (cfsl Group Area Flow <cfs J Group Area Flow (cfs) Group 126.30 R 27000 II 137.20 R 10400 Ill 1 00.40 R 12500 Ill 115.60 R 23000 II 127.00 M <51 00 IV 137.50 R 22000 II 100.60 R 33000 II 116.80 R <5100 IV 127.10 M <51 00 IX 137.80 L 20000 II 100.60 L 9200 Ill 117.00 M 15500 v 127.20 M us I 137.90 L 21000 II 100.70 R <5100 IV 117.10 M 15500 V Ill 127.40 L <5100 IV 138.00 L 8000 VI 101.20 R 9200 Ill 117.20 M 20000 VIII 127.50 M <5100 VII 138.71 L MSS X 101.30 M 9200 VIII 117.70 L <5100 IX 128.30 R <5100 IX 138.80 R 6000 VI 1 01.40 L 22000 II 117.80 L 8000 Ill 128.40 R 9000 VIII 139.00 L us I 101.50 L <5100 IX 117.90 R 7300 VI 128.50 R 10400 Ill 139.01 L MSS v 1 01 .60 L 14000 Ill 117 .90 L 22000 II 128.70 R 15000 Ill 139.20 R <5100 IX 101.70 L 9600 Ill 118.00 L 22000 II 128.80 R 16000 Ill 139.30 L MSS X 101.71 L MSS v 118.60 M 14000 VIII 129.30 L <5100 IX 139.40 L <5100 IV 101 .80 L 22000 II 118.91 L MSS v 129.40 R us I 139.41 L MSS X 102.00 L 10000 VIII 119.11 L MSS X 129.50 R <5100 IV 139.50 R 8900 VI 102.20 L us I 119.20 R 10000 VII 129.80 R <51 00 IX 139.60 L <51 00 IV 102.60 L 6500 VI 119.30 L 16000 Ill 130.20 R 12000 Ill 139.70 R 22000 v 104.00 R <5100 IX 119.40 L us I 130.20 L 8200 Ill 139.90 R us I 1 04.30 M 21000 VIII 119.50 L 5000 IV 131 .20 R <5100 IX 140.20 R 26500 II 105.20 R us I 119.60 L <5100 IV 131.30 L 9000 VII 140.40 R <51 00 IV 105.70 R <51 00 IX 119.70 L 23000 VI 131.70 L 5000 IV 140.60 R 12000 VI 105.81 L MSS X 119.80 L 15500 VIII 131.80 L 26900 II 141 .20 R <5100 IX 106.30 R 4800 VI 120.00 R us I 132.50 L 14500 V Ill 141 .30 R <5100 IX 107.10 L 9600 VI 120.00 L 12500 VIII 132.60 L 10500 Ill 141 .40 R 11500 Ill 1 07.60 L us I 121.10 R <51 00 X 132.80 R 19500 v 141.60 R 21000 v 108.30 L us I 121.10 L 7400 VII 133.70 R 11500 Ill 142.00 R 10500 VI 108.70 L <51 00 IV 121.50 R 19500 VIII _13~~ 17500 VI 142.10 R 23000 II 108.90 L <5100 IX 121 .60 R 15500 VIII 133.81 R MSS X 142.20 R 26000 II 109.30 M MSS X 121.70 R <51 00 IV 133.90 R 30000 II 142.80 R <5100 IX 109.40 R <5100 IX 121 .80 R 22000 II 133.90 L us I 142.80 L MSS X 109.50 M 16000 VIII 121.90 R us I 134.00 L us I 143.00 L 7000 v 110.40 L 12000 Ill 122.40 R 26000 II 134.90 R <51 00 IV 143.40 L 23000 II 110.80 M <51 00 IV 122.50 R 20000 II 135.00 R 21500 VIII 144.00 R <5100 IX 111.00 R <5100 IX 123.00 L <5100 VII 135.00 L <51 00 IX 144.00 M 22000 V Ill 111.50 R <51 00 IV 123.10 R us I 135.10 R 20000 VIII 144.20 L <5100 IX 111 .60 R 11500 X 123.20 R 23000 VIII 135.30 L 23000 II 144.40 L 21000 II 112.40 L 22000 VIII 123.30 R us I 135.50 R us I 145.30 R <5100 IV 112.50 L us I 123.60 R 25500 II 135.60 R 42000 I 145.60 R 22000 VIII 112.60 L <51 00 IV 124.00 M 23000 v 135.70 R 27500 VI 146.60 L 26500 VIII 113.10 R 26000 II 124.10 L <51 00 IV 136.00 L <51 00 IV 147.10 L <5100 IX 113.60 R 10500 X 124.80 R 19500 VIII 136.30 R 13000 VI 148.20 R MSS X 113.70 R 24000 II 125.10 R 20000 II 136.90 R us I 113.80 R <51 00 IX 125.20 R <51 00 IV 113.90 R 7000 X 125.60 L <5100 VII 114.00 R <51 00 IV 125.60 R 26000 VIII 114.10 R <5100 VII 125.90 R 26000 II 115.00 R 12000 Ill 126.00 R 33000 II MSS = Malnstem Shoal US = Upland Slough - q Table A-2. Surface areas by discharge tor Individual specific areas of the middle Susltna River. Areas are In square Inches measured at a scale of 1 Inch= 1000 teet (1 square Inch= 22.95 acres). The line Indicates pa+ween which two analyzed discharges breaching of the Speci t lc Area -102.2 L -105.2 R -107.6 L -108.3 L _l!£:1~~L~~~ 119.4 L 120.0 R >i:J2 121 .9 R ... ::J2_3. 1 R 123.3 R 127.2 M 7''~,~-129 4 R I0-133.9 L 7 134.0 L 135.5 R 35.6 R :36.9 R 7-139.0 L --' 139.9 R Individual channel occurred. REPRESENTATIVE GROUP I Discharge (cfs) 5' 100 7,400 10,600 12,500 16,000 .054 .041 .054 .048 .046 .000 .010 .008 -~ .039 .034 .035 .016 .018 .024 .032 .023 .023 .018 .024 .J 13~~/C~ .099 . 111 .127 .115 .000 .000 .000 .018 .0,19 .039 z .049 .051 .052 .050 ~9-, .008 .033 .006 .012 ~orr~ .010 .022 .021 .014 .000 .058 .050 .025 .024 .005 .006 .008 .027 .028 ~·000 .098 .097 .062 .060 • o4~5~~~.o56~~~~:o74~~~ :037-c~c····· :-o48 .016 .025 .014 .008 .014 .000 .045 .036 .000 .042 .168 .152 .159 • 139 .170 .007 .006 .017 .018 .053 .011 .084 .036 .051 .047 .OJ2 .020 .000 r:~ooo .013 2 18,000 23,000 .054 .040 .030 .036 .024 .094 .014 .024 • 119 .125 .043 ~o32 ~----<r''' .050 .092 .013 ~ .047 .037 .051 .038 .042 .031 ~~d~-048~-~~d.~~c&4 9 ~· .049 .055 .013 .019 .039 .042 .275 ~ .134 .044 .081 .012 .035 l\"\ 13/.::.> L. 137.8 L 137.9 L Zo ~0.2 R 142.1 R 143.4 L if:< 144.4 L 142.2 R .013 .000 .058 .000 .000 . 101 * '-'I>"' .v ·- .000 .072 .000 .000 .098 * ESENTATIVE GROUP I I Discharge (cfs) 10,600 12,500 16,000 .042 .038 .044 .086* .170 . 180 .030 .038 .040 .000 .007 .013 .040 .024* .037 .174 .175 .132 .044 .054 .042* .007 .000 .022 .037 .053 .044 .000 .000 .000 .270 .293 .246* .044 .049 .065 .089 • 137 .000 .035 .055 .062 <-ff8, .619 .684 ~n6 .1 02 ::284 .025* .014 .018 .056 .068 .071 .000 .000 .015 .039 .043 .032* • 113 .031 .024 .039 .035 .059 .000 .041 .059 .084 .072 .134 .000 .062 .017* .027 .048 .052 .119 • 117 .125 * .018 * 18,000 23,000 .035 .207 .039 .020* .054 .254* • 104 .030 .053 .000 .189* .052 . 123 .161* .680 ~ .114* .015* .039 .054 .080 .061 .033* .119* .075 .070 • 124 * Table fr2. Specl f lc Area 5 '1 00 -102.2 L .054 -105.2 R .000 -107.6 L .034 ~108.3 L .032 112.5 L • 113c ~~,-~,,_-~,"'~,~~"~'''~''''F'~-v 119.4 L .000 120.0 R Surface areas by discharge for Individual specific areas of the middle Susltna River. Areas are In square Inches measured at a scale of 1 Inch= 1000 feet (1 square Inch= 22.95 acres). The line Indicates between which two analyzed discharges breaching of the Individual channel occurred. REPRESENTATIVE GROUP REPRESENTATIVE GROUP II Discharge (cfs) Discharge (cfs) Spec It lc 7,400 10,600 12,500 16,000 18,000 23,000 Area 5' 100 7,400 10,600 12,500 16,000 .041 .054 .048 .046 .054 .040 100.6 R .039 .043 .042 .038 .044 .010 .008 ~ .039 .030 .036 101 .4 L • 160 • 153 .086* .170 • 180 .035 .016 .018 .024 .024 .094 101 .8 L .038 .034 .030 .038 .040 .023 .023 .018 .024 .014 .024 113.1 R .000 .000 .000 .007 .013 .099 .11 L~ .127 .115 .119 .125 -113.7 R .041 .038 .040 .024* .037 • of9 :o32·~ .......... .000 .000 .018 .043 115.6 R .000 .367* .174 • 175 .132 .049 .051 .052 .050 .050 .092 JS'<Y~ _,::,<.--1 1 7 • 9 L .019 .016 .044 .054 .042* .039 z 'ii;12 121 .9 R ~v .008 .033 .006 .012 .013 ~ 118.0 L .011 .008 .007 .000 .022 ... ::I'z3. 1 ~o·oo -R .010 .022 .021 .014 .047 .037 121.8 R .035 .036 .037 .053 .044 123.3 R .000 .058 .050 .025 .024 .051 .038 122.4 R .005 .024 .000 .000 .000 127.2 M .005 .006 .008 .027 .028 .042 .031 122.5 R .240 .242 .270 .293 .246* 9 ~· .. ··-129 4 a -.ooo .098 .097 .062 ·2.~9-~~~·~-0.48 ..... ~ .... ~.,..04~ .•. -123.6 R .031 .067 .044 .049 .065 -133.9 L ~. a·45~~~~~·~~.o74~·~··· :o37~-~. -~048 .049 .055 125.1 R .000 .011 .089 • 137 .000 .134.0 L .016 .025 .014 .008 .014 .013 .019 125.9 R .054 .048 .035 .055 .062 "" 135.5 R .000 .045 .036 .000 .042 .039 .042 ___J_26.0 R .498 .537 <'ffB' .619 .684 ?.__ 35.6 R .168 .152 .159 .139 .170 .275 ~ 126.3 R .000 .084 ~n6· .102 .:284 136.9 R .007 .006 .017 .018 .053 .134 131.8 L .000 .000 .025* .014 .018 7-139.0 L .011 .084 .036 .051 .047 .044 .081 133.9 R .021 .043 .056 .068 .071 ...; 139.9 R .0.12 .020 .000 .::·ooo .013 .012 .035 135.3 L .000 .000 .000 .000 .015 ~v~Vvv""=v~=~ 137.5 R .014 .014 .039 .043 .032* 137.5 L .1 06 .113 • 113 .031 .024 137.8 L .013 .016 .039 .035 .059 137.9 L .000 .000 .000 .041 .059 !tJwGy zo __uo.2 R .058 .072 .084 .072 .134 f!vrs 2 142.1 R .000 .000 .000 .062 .017* 143.4 L .000 .000 .027 .048 .052 << 144.4 L .101 .098 • 119 .117 .125 142.2 R * * * .018 * *deleted from further - 18,000 23,000 .035 .207 .039 .020* .054 .254* . 104 .030 .053 .000 .189* .052 .123 .161 * .680 G:Q§B .114* .015* .039 .054 .080 .061 .033* .119* .075 .070 .124 * Table ~2. Specific Area 5,100 100.4 R • 11 0 100.6 L .050 101 .2 R .045 101 .6 L .059 101.7 L .313 110.4 L .153 115.0 R • 109 119.3 L .000 128.5 R • 144 128.7 R .080 128.8 R .253 130.2 R .525 130.2 L .022 132.6 L .000 133.7 R • 181 137.2 R .116 141 .4 R .262 Surface areas by discharge for Individual specific areas of the middle Susltna River. Areas are In square Inches measured at a scale of 1 Inch= 1000 teet (1 square Inch= 22.95 acres). The line Indicates between which two analyzed discharges breaching of the Individual channel occurred. REPRESENTATIVE GROUP Ill REPRESENTATIVE GROUP IV Discharge (cfs) Discharge (cfs l Specific 7,400 10,600 12,500 16,000 18,000 23,000 Area 5,100 7,400 10,600 12,500 16,000 • 115 .120 • 174 • 161 .325 100.7 R .775 .828 .889 .910 .972 .056 .100 .139 .137 .162 108.7 L • 178 .190 • 198 .204 .221 .124 .272 .317 .455 .492 110.8 M .174 * .182 .188 .184 .070 .0 9 • 112 • 153 • 166 111 .5 R • 764 .919 .999 1.113 1.180 .297 .670 .697 .720 .800 112.6 L 1.730 1.660 1 .934 2.116 2.290 .097 .272 .342 .399 .420 114 .o R 1 .450 1.703 1. 706 2.116 2.326 .225 .735 • 780 1.135 1 .231 116.8 R .366 .41 0* .399* .383 .41 5 .017 .076 .086 .096 • 111 119.5 L .351 .376 .400 .505 .518 • 143 .379 .894 • 724 .919 119.6 L .000* 1 .274 1 .216 * 1.304 .077 .184 .315 .343 .389 121.7 R 1 .311 1 .380 1 .611 1.762 1 .990 .250 .286 .591 .435 1 .281 124.1 L * .792 .900 .890 .933 .430 .563 .902 1.127 1.462 125.2 R 1.582 1.528 1 .872 2.198 2.405 .017 .079 .129 • 121 • 145 127.0 M .216 .215 .310 .292 .326 .043 • 193 .295 .325 .441 127.4 L 1.217 1.217 1 .256 1 .295 1.434 .170 .149 .237 .222 .352 129.5 R .497 .486 .526 .547 .270* .122 .401 .435 .484 .579 131.7 L .231 .774 1.158 .088* 1 .584 .268 .459 .649 .696 .927 134.9 R 1.278 1 .372 1.468 1 .451 1.882 136.0 L .038 .041 .048 .054 .061 139.4 L • 123 .168* • 137 .188* • 156 *deleted from further analysis 139.6 L .548 .528* .472* .595 .637 140.4 R .338 .331 .567* .445 .471 144.0 R .617 .548 • 193 .339 .368 145.3 R .251* .229 • 160* .239 .234 *deleted from further analysis 18,000 23,000 1 .162 1 .243 .227 .246 .178* .208 1.197 1.423 2.338 2.309 2.517 2.152 .325* .433 .524 .601 1 .363 1 .378 2.061 2.363 1.116 • 768 2.335 2.453 .377 .339 1.554 1.502 .406* .716 1.738 2.072 1 .915 2.182 .066 .071 .147* .161 .612* .688 .407* .517 .284 .190 .255* .241 Table A-2. Specific Area 5,100 101.7 L .313 117.0 M .000 124.0 M .ooo 132.8 R .021 139.0 L .011 139.7 R .000 141 .6 R .094 143.0 L .019 Surface areas by discharge for Individual specific areas of the middle Susltna River. Areas are In square Inches measured at a scale of 1 Inch= 1000 feet (1 square Inch= 22.95 acres). The I lne Indicates between which two analyzed discharges breaching of the Individual channel occurred. REPRESENTATIVE GROUP V REPRESENTATIVE GROUP VII Discharge (cfsl Discharge (cfs) Specific 7,400 10,600 12,500 16,000 18,000 23,000 Area 5,100 7,400 10,600 12,500 16,000 .297 .450 .670 .671 .261* 114.1 R .256 .338 .386 .393 .442 .000 .000 .032 .093 .310 119.2 R .122 .120 . 196 .206 .283 .019 .044 .052 .103 .157 121.1 L .060 .094 .173 .242 .322 .807* .015* .023 .042 .045 123.0 L .040 .046 .000* .054 .047 .084* .036 .051 .047 .044* 125.6 L • 141 .000* • 151 .182 .146* .000 .000 .000 .000 .005 127.5 M .281 .335 .334 .430 .363 .1 00 .072* • 111 • 112 .148 131.3 L • 11 0 .072 • 163 .292 .405 .026 .084 .090 .089 .084 *deleted from further analysis *deleted from further analysis REPRESENTATIVE GROUP VI Discharge (cfs) Specific Area 5,100 7,400 10,600 12,500 16,000 18,000 23,000 102.6 L • 143 .330 .414 .479 .488 .520 106.3 R .086 • 117 • 156 • 161 .159 • 180 107.1 L .000 .207 .212 .363 .436 .698 117.8 L .081 .123 .170 • 194 .262 117.9 R .041 .036 .038 .041 .071 119.7 L .040 .000 .025 .058 .045 _133.8 L • 130 • 166 .201 .216 .378 135.7 R .000 .000 .071 * 6 .064 136.3 R .062 • 116 .134 .175 .336 138.0 L .000 .070 .163 • 194 .1 09* .224 138.8 R .008 • 119 • 154 .142 .193 139.5 R .163* .296 .423 .549 .692 140.6 R .041 .325 .363 .315 .574 142.0 R .066 .266 .360 .623 .747 *deleted from further analysis 18,000 23,000 .000* .489 .334 .330 .503 .581 .116* .079 .228* • 198 .708* .495 .532 .649 Tab I e A-2. Specific Area 5,100 101 .3 M .000 102.0 L .000 104.3 M .000 109.5 M .000 112.4 L .000 117.1 M .000 117.2 M .000 118.6 M .007 119.8 L .000 120.0 L .000 121 .5 R .000 121 .6 R .000 123.2 R .012 124.8 R .000 125.6 R .000 128.4 R .000 132.5 R .000 135.0 R .000 135.1 R .000 144.0 M .000 145.6 R .000 146.6 L .000 Surface areas by discharge for Individual specific areas of the middle Susltna River. Areas are In square Inches measured at a scale of 1 Inch= 1000 feet (1 square Inch= 22.95 acres). The line Indicates between which two analyzed discharges breaching of the Individual channel occurred. REPRESENTATIVE GROUP VIII REPRESENTATIVE GROUP IX Discharge <cfs) Discharge (cfs) Spec It lc 7,400 10,600 12,500 16,000 18,000 23,000 Area 5,100 7,400 10,600 12,500 16,000 .000 .038 .045 .097 .061* 101 .5 L 1 .343 1 .278 1 .208 1 .239 1 .651 .000 .058 .090 .098 .091 104.0 R .641 .631 .631 • 716 .698 .000 .000 .000 .000 .065* 105.7 R .363 .419 .358 .407 .417 .000 .000 .000 .000 .014 108.9 L .307 .272 .290 .283 .333 .000 .000 .000 .000 .035 109.4 R .917 .951 .990 1 .081 1.062 .000 .000 .071 .271 .447* 111 .0 R .896 .939 1 .033 1.062 1.258 .000 .000 .000 .000 .024 113.8 R • 135 .123 .145 .154 .171 .025 .013 .021 .034 .054 117.7 L .173 .203 .162* .218 .292 .000 .000 .000 .031 .091* 127.1 M .403 .404 .442 .537 .628 .011 .036 .086 • 160 .064* 128.3 R .684 .815 .884 1.094 1.009 .000 .000 .000 .034 .105 129.3 L • 179 • 181 .142* .178 .163 .000 .000 .000 • 135 .339 129.8 R .572 .626 .619 .618 .656 .018 .023 .025 .016 .055 131.2 R .142 .185* .133 .139 .161 .000 .010 .023 .067 .074 135.0 L .212 .201 .190 .192 .202 .000 .016 .012 .011 .029 139.2 R .434 .458 .516 .530 .583 .000 2 .132 .144 141 .2 R .130 .189* • 194 .142 .152 .000 .000 .097 .054* 141 .3 R .294 .000* .297 .290 .288 .000 .000 .041 .000* 142.8 R .839 .925 1 .1 00* .978 1.264 .000 .000 .058 .000* 144.2 L 1 .846 1. 787 1 .133* 1 .127* 1.838 .000 .000 .000 .000 147.1 L .516 .503 .552 .497 .534 .000 .000 .000 .180 .000 .000 .000 .010 *deleted from further analysis *deleted from further analysis 18,000 23,000 1.698 2.661 .679 .887 .389 .447 .366 .401 1 .072 1 .218 1 .149* 1.368 .186 • 181 .087* .345 • 738 .887 1 .096 1 .566 .132* .266 .463* .686 .169 .226 .188* .212 .51 0* .662 .056* .244 .332 .331 .582* 1 .305 • 709* 1.943 .611 .675