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HomeMy WebLinkAboutBlack Bear Creek Monitoring Work 1986BLA 033 8AJP~~ ENVIRONAID 12175 MENDENHALL LOOP ROAD. JUNEAU, ALASKA 99801 · (907) 789 ·9305 Alaska Energy Au thor ity LIBRARY COPY final report on Black Bear Creek Monitoring Work Fall, 1985 and Late Winter, 1986 Daniel M. Bishop April 24, 1986 Black Bear Creek Monitoring Work, Fall, 1985 and Late-Wintert 1986 This report terminates environmental investigations and monitoring regard- ing the proposed Black Bear Lake Hydroelectric Project, and is designed to complete the work identified by contract with Harza Engineering Company dated 13 August, 1985. Additionally, an evaluation of the temperature records is provided. This has been done to make the work more useful to future users of the data. 1. Water temperature values for 1984-85 and 1985-86 are plotted in Figures la, lb and 2a, 2b. The 1984-85 records are complete without instrument malfunction. The 1985-86 records contain only two months of record for the outlet of Black Bear Lake, and the thermograph at the stream gravel site failed to function properly and was also re- moved from the streambed in November, apparently by a hunter. A discussion of the 1984-85 record is provided in the October 10, 1985 interim report. A more comprehensive evaluation and discussion of both 1984-85 and 1985 ... 86 records has been made for this report. The objectives of this evaluation are: a. to describe the contrasting fall-winter conditions in s0 far as character of lake temperatures in 1984-85 and 1985-86 are con- cerned. b. to examine the relation between temperatures at -20 feet, near the outlet of Black Bear Lake and temperatures downstream, particularly at the head of the Spring Fork. c. to review the full record of cumulative water temperatures, in- cluding the data obtained by this work. d. to provide temperature relationships which can be used to infer missing temperature data for the outlet of Black Bear Lake (BBL) and the Stream Gravel Site (SGS). li' .. I ii ... : ... !f o'-' :l j; a ~ ... .. .. i 12 u• 8 6 ' 2 1Z 10 a 6 4 I(Jf; G>: IIOV.l Figure 1•: -2- Ave:ratte d.aily ti!CII!)rr&turea for thre-e aitn at and ..,.ediately below Block Bear Lake, Oct:obtr 1984 through August 1985. .1!1 ~ ~~. "' OEC.l Figure 1b: Average dail,. t""'l'erawrn for three oitea below P-.rhou.oe Site, !laclr l!eor Cnek, w.,.,.ber 19114 thr""'!h Auguot 1985. •• .,._w--.• #'\. ,../ .. , ...... ~, "-· .. _, 1 ' • , "' ""'"t • I .• '\ ~-~,_ ··...... \ t~rv...--·"';. .i , \,~ IIOV.1 DEC.l • JA!'I.l JA.~.l ~ ~?·· ..• 0' . .~··"'? .. ~ : .. ·~-_, C>.·o :. (!I ' ~-· • <I ... ,I ' ' w . ns.1 ~ ~ ..... J-.... , ' , ' , .. , v """""' 'J '"' \ .. · .. --: ,_'\ e·e·e·e -20 ft., Black Boar Lake (troiS) outlet, 8bck Bear l..ak• (BilL) Poverhouoe Site (PHS) ,/Ji;, til q> t! Iii : : : -. • ·i:. •• ···"! "lil : .. & • : ... : <a .., ••• ~. . : ~ .. • .. ~\ ._ ..... . 0 G. ~-~;,/ .. (!#:. ~· G : :o .. ·,: <I " 0.: .I t\i Cl I <t / ~ ~ ,.''-.• i 104 G) j }'-·/ (:) r . tr: ' : ';,1 •• , •• ·<;> :··· !); ~ •• ;Ia ... '!,l .,, \~ l!!ll-~ ,'!''· t_~f~ .. ~·-0_~ .. ·~.11 .... · w -.. , ___ ., _,:.,..,.--..,.,.......~,,....._--_, .... _~,~·'J~""""\.-.... -'*:-fi_'IQ.. ""c)--.I""'"'""""".})~--........... __ .. ,_.,,_.,. __ .,........,.,-'""'-----_.., ... ~ -........ ., ... ., • ~ : ,. : .It ........ o C!l• . ., <!o" Q ~~ IWLl API!.. 1 Upper Black l..>ke (UBL) Spring Fork Site (SFS) Stream Cravel Site (SGS) MAY 1 JUII£ 1 JULY 1 "~I I i •' " ,· '· ,· ·' >•' -.-', ,'\ , (~ ' o'.' .. A ,-,•/ ''• ,• ,.•, f '•' \ •\, .. ~ : C ' •' v' ' ' • .'.' " ' / ' ' " " •'' ' '' ' '' ' ' '' ' '' ' ' \! y~l ~ ·~~·.. ' '--.: ' ' ' ·."! . ' •/ ' . . ~ . ,, ~·::-~-~, t' ......... ··· F£8.1 !!Alt. 1 Al'll. 1 HAY l JUI'f. l JULY 1 .~ f> ~ .: . :~ ~ ·~ <!>. •' .!>:~ ~f !!>,;,: <!)' ~:,. I ~ ; . ; dl "'" ? I. AUG. l SEPT. 1 AUG.l SEPT.! I~ lO 8 " 1 12 10 8 6 4 -3- 0 G o· e··. ~ G ~. Fl ~ ·~· d \~ . ...... '""' 'il . " ' . "< • • (;;• 0 Q ~ --cl. \ . ~ :· Fi~r-e:~~· Averagt' d.1ily three sitrs "'t SE.P7 I ,, . \ below Black Re:n-L.lil:l!', Scpren:~her 1985 through mid·l'lnch 1986. OCT.! FisurP 2b~ Average daily t~peratures for two sites below Po'-'frhousf! Site. !llack har Creek, Seplrmber 1985 through •id~Harch 198&. SEPT. I ocr .I 0·0 0 Q -20 Ct , Bl~ck S~ar W.k~ (ll'./S) outht. Black B.-ar Lake (BSL) Po\.:c:nouse Site (PHS) 0-. ' G·<i( : . 'f; El': ('} G>· ~-.Q ,.;:\ : ' • ' o ·. ·~ <;l r ', . ' , 1 , •. ; •• , 11: • •' : G·' ' o • \ ~ ; \ . .<f'l I!> ' • I> G· . • • • " • : •• ' G ; , ,,.~----~---~~--,_,---, ~---, _ _.---,_.,.J--..,,_CiJ.J<i-.l;;l--~~< •'· ··:• ,. A.r.,_rJ, ' "'· • G_,., •• , -.. : • •. • rp· 0 . : · . ·-;----r::r~ -:-,r---::--: ~-"' ~>-,-__ , .,_" o-. : ' "' , ·• . 0 •. l;j • d 0 • "' 0· ",.., -.~ .. \ .0•' 0 Gl Q c:.. ; IIOV .I 'f : ... ., -· 0 0 . "(l> : l1 ·o· .. ., . ., o o e-.G .... e DEC.! ' -, -,"' ... -, ,, .... ,, .. "', -,, ............... ~_,1 DEC.! JA!'f.l n:a. 1 Upper l!hck Lake (UBL) Spring Fork Site (SFS) \ ' "'"_.., ,, , \ til ' ,-' \ ,. ... t ' .~ ... ',' , .. , ., ... , JAN. I fEB.} \ \ . ,'\I ' . I".AR. I MAR. 1 ~--~''\..,­ l-"-' ' •t APR.! APR.} - 4 - In fall, 1984, Black Bear Lake appears to have developed an ice cover on about December 16 and the ice persisted till early to mid June. In fall, 1985, Black Bear Lake appears to have developed ice cover about the lOth of November. Ice was present on the lake when we measured the temperature profile on 3-20-86, although the lower end of the lake was broken up and we made our observations from an ice floe. These contrasting fall-winter conditions affected the character of lake temp- eratures and thus both lake discharge and sub-surface temperature re- cords. The differences between temperatures at -20 feet under the outlet of Black Bear Lake (UWS) and at the Power House Site (PHS) are shown as component(a)of Figure 3. A conceptual curve of the plot is also shown, suggesting that UWS is colder than PHS during late spring to October; as much as 4°C difference can develop during summer. During fall and winter, however, the difference between stations fluctuates exten- sively, primarily as a result of either cooling or warming influence of the falls between the lake outlet and the powerhouse site. During cold winters or cold periods during winters, UWS temperatures are l°C or more higher than comparable PWS values. During "open" winters or rainy periods, UWS temperatures are l°C or more less than values at PWS. Thus the information plotted in Figure 3a suggests that the gen- eralized average of UWS values during September through March (the sock- eye salmon incubation period) are apt to be similar to the average of the more fluctuating PHW temperatures. It is possible to approximate the effect upon cumulative temperature units of drawing water from the vicinity of -20 feet below Black Bear Creek, and discharging this flow at the powerhouse location. It is assumed here that measured UWS temperatures are a reasonable approxi- mation of water temperatures in a future tailrace. The data suggest that the average temperature of water pulled from -20 feet at Black Bear Lake outlet during September and early October would reduce cumulative temperature units by around 40 T.U. 's (°C). 0· -Oc <'1.· <D2: ':t; 0 \) .0 a: w :X:(J) <ll "'Z "' w -"0 " .,._ "'Ill _, ,..-" Ill~ ~ a: a 5 <O ... WO) "' >-- ->< ~ ~~ = +3·c +z• ,..,. -t -z• -3c -t,e•c. +1 • .. ,. -z~ Figure 3: 5 Differences in water temperatures between selected stations in upper Black Bear Creek. - 6 - Thereafter, until mid-March the variable differences between UWS and PHS suggest patterns which vary according to the severity of the winter. From Late October 1984 to early March 1985 the UWS cumul- ative temperature units were approximately 30 less than for the PHS temperatures. For about the same period in 1985-86 the UWS temper- atures, accumulated about 50 more temperature units. Below the powerhouse location, discharged water would presumably pass through present surface/groundwater flow routes. This transition from the powerhous~ into the stream at the head of the Spring Fork is exam- ined in Figure 3b. It suggests that temperature differences, during fall to early spring will be small or insignificant between flows or- iginating from the outlet of Black Bear Lake as compared with flows taken from the vicinity of the UWS. Two conclusions now appear reasonable regarding the cumulative temper- ature units, September 1 to March 15, with the proposed water with- drawal below Black Bear Lake's outlet: first, significant alteration in temperature units for the present average pattern appears unlikely; and, second, less variability is likely for the date when cumulative temperature units reach the fry outmigration period. Summary figures for cumulative temperature units in Black Bear Creek are given in Table 1, below. Taole 1: Cumulative temperature units for Upper Black Bear Creek September 1 to March 15 Year 1980-81 1981-82 1982-83 1983-84 1984-85 1985-86 1/ UBL for I_! SFS and Observation Station UBL 1_/ SGS SGS not measured SGS SFSJ:j Cumulative Temp. Units 1060.8 1153.0 1046.5 not available 949.2 943.4 3 yrs. of comparison averaged 79 T.U.'s less than SGS. SGS values are considered comparative here. - 7 - During mid-March the temperature unit accumulation rate is around 2.5 -3.5°C/day. As the dates advance following mid-March, the daily accumulation would increase. This evaluation suggests that the date of reaching 1000 T.U.'s has varied more than a month in upper Black Bear Creek during the periods of observation. This compares reason- ably with variation in observed dates of pink salmon fry outmigration for other S.E. Alaskan streams as summarized below: Sashin Creek 22 years record 1 1/2 month variation Auke Creek nearly a month variation Kadashan River nearly a month variation In conclusion, it is likely that outmigration timing under regulated or partially regulated flow conditions will fall within the normal range. Late spring through summer water temperatures are likely to experience significant change downstream of the proposed hydroelectric power dev- elopment. During May through September the drainage from the powerhouse is likely to be one or more degrees centigrade less than present flows passing the powerhouse site. The temperature moderating role of flow routes between the powerhouse site and the Spring Fork during summer months is an area for speculation; presently this route, which is predominantly groundwater fed in low flows, tends to warm water flows in winter and cool flows in summer. The speculation at this time lies in estimating the degree to which a ground water flow route for the relatively cold waters discharged in summer from the powerhouse will act to raise temperatures. It is possibletherewill be little alter- ation of the powerhouse discharge temperatures, leaving the summer waters one-to-several degrees colder than normally experienced. There are periods when temperature records are defective or lacking for one station, while a nearhy station's record is good. In view of the fact that the temperature relationship between stations changes according to weather and season, a regression relation cannot effect- ively be used. For that reason, the future user of temperature data may find the plots of Figure 3 useful for inferring relationships at a specific date and condition. - 8 - 2. Lake profile measurements for late August, 1985 and late March, 1986 are provided as Figures 4,5,6, and 7. The dissolved oxygen meter failed in the field in March, preventing us from measuring oxygen levels. a. Lake temperature profiles in late summer, 1985 show both lakes with low heat content. Black Bear Lake, in particular, showed a very sharp thermocline on 8-29-85 at 30 ft. depth, below which the lake reached record low profile temperatures for the season. The March 20, 1986 temperature profile for Black Bear Lake, mea- sured from an ice floe platform, falls on the low side of observed winter profile values. Black Lake on 3-19-86 was ice-free and nearly isothermal (ca.4°C.) throughout its depth. 3. Adult salmon escapement counts were made on 8-28 and 2-29-85. These counts for sockeye and pink salmon are summarized along with compara- tive data from earlier years in Table 2. Sockeye counts for 1985 are consistent with those of earlier years. The abs·ence of sockeye adults in or below Black Lake and the distri- bution of spawners throughout the channels above Black Lake further establishes the peak of adult sockeye spawners above Black Lake as occurring the last week in August. The Klawock River hatchery counted sockeye entering Klawock Lake in summer, 1985. These data are somewhat relevant to the observations of sockeye in Black Lake. Hatchery manager Steve Hansen reports that their counting weir operations began on 7-19-1985, at which time they estimated that 55 sockeye were above the weir. Cumulative weir totals for sock- eye are as follows: c.,) 10- 0 Ql ""' ::l -1.1 cu ""' Ql 3-0. m E-t ""' Ql -1.1 cu 3: 20 40 - 9 - 9/6/84 60 Deoth. Feet 80 10/30/84 8/29/85 100 Figure 4: Profiles of Spring, Summer, Fall and Winter temperatures in Black Bear Lake. 1984 values emphasized; Fall, 1985 profile shown in red. t.J • CIJ 1-1 :l 4.J t'O 1-1 CIJ 0 e CIJ ~ 1-1 CIJ 4.J ~ -10 - Spring Summer Fall \-linter 8 10/29/84 3/19./86- 0~--------,-----------,----------.-----------~-----------~--------- 10 20 30 DeDth. Feet 40 so Figure 5: Profiles of Spring, Summer, Fall and Winter temperatures in B.lack Lak';· 1984 v~ues ~phasized;_ Fall, 198S profile shown in red. I . 5 . Q. . c. I t: 41 00 >->< 0 "0 41 > ..... 0 (Jl g) ...... Q I I 14 12 10 8 6 4 2 20 40 -11- g = Summer ~ = Fall 60 Depth, Feet 80 100 10/30/84 8/29/85 9/6/84 Figure 6: Profiles of Summer, Fall and Winter dissolved axygen ·levels in Black Bear .Lake. · 1984 values emphasized; Fall, 1985 profile shown in red. I . a . ~ ~ I c: QJ eo >. ~ "0 Q) > ...,j c tO Cll .,.... Q I -12 - 14 12 10 8 6 4 ' Spring Summer Fall ~-linter 3/26/84 10/29/84 8/28/85 .0~--------~--------~--------~----------~------~ 10 20 30 Depth. Feet 40 ·50 Figure .7; Profiles of SprinR. Summer. Fall and Winter dissolved · oxygen levels in Black Lake. 1984 values emphasized; Fa ll, 1985 profile shown in red. C"'") r-i Species Sockeye Pink Date of Observation 8/28/85 8/30/85 8/27/84 8/28/82 8/28/81 8/28/85 8/30/85 1984 1983 1982 9 I 16/81 Black Lake to W. Branch 142 255 57 176 165 200 87 I_ 121 Table 2: Counts of adult sockeye and pink salmon above Black Lake showing 1985 and earlier observations. Reach of Stream West Forks to South South Fork South Fork Spring Fork. Branch Fork dam Pond above pond above W. Br. 49 124 108 141 216 116 8 96 179 . 223 88 15 36 56 26 7 81 129 0 0 442 43 ------------337 ------------ 145 + 500 2 3 1 27 336 28 8 16 66 363 No spawning pinks above Black Lake Spawners probably present -no count made No spawning pinks above Black Lake 148 I -----------1,752-------------I 1,267 - Lake Fork 3 - 52 0 0 5 3 I 619 Total Count 783 877 571 828 1,190 574 571 3,907 f-' w July 19 29 Aug. 8 18 28 Sept. 7 17 20 -14 - 55 sockeye (above weir) 108 154 154 910 (most of these fish passed through on Aug. 27-28) 954 1020 1039 total for sockeye counted through the weir. Later examination of spawning streams tributary to Klawock Lake (above the weir) indicated considerably more fish -possibly twice as many as counted through the weir. This higher count is likely due to the percentage of the sockeye adults passing through the weir pickets. This comparison suggests that sockeye adults reaching upper Black Bear Creek (via Big Salt Lake, Black Bear Creek and through Black Lake) arrive on their spawning grounds one to several weeks before the Klawock Lake sockeye. It may be that colder temperatures for in- cubation prevail in upper Black Bear Creek than in the sockeye spawn- ing streams of Klawock Lake, requiring longer incubation periods in upper Black Bear Creek. Over the years of observing sockeye spawning in upper Black Bear Creek an apparent pattern of spawning in locations of more iron-stained gravel has emerged. This behavior suggests an hypothesis that sockeye spawners in Black Bear Creek seek out preferred spawning sites by sensing higher dissolved iron concentrations in water emerging from certain areas of the upper stream. The survival advantage of this hypothesized behavior may be in either better associated thermal re- gime or more stable (deeper fed) upwelling flows of such selected areas. Additional specialized studies would be needed to examine the accuracy of this concept. The spawning run of pink salmon entering upper Black Rear Creek in sum- -15 - mer, 1985 marks a bi-annual event. The previous observed run in 1981 followed sockeye spawning and peaked on the spawning ground during the second week in September. This run of nearly 4,000 fish spawned over the previous sockeye redds and probably induced mortality to sockeye eggs. At the time of our visit in 1985, several thousand pink salmon -we estimated in excess of 5,000 fish -were holding in Black Lake and at the mouth of Black Lake. These spawners were probably bound for the upper Black Bear Creek spawning areas, where they would again spawn over sockeye redds. An abundance of pink salmon spawning above Black Lake may have two effects: (1) reduce the number of emergent sockeye fry surviving to migrate into Black Lake next spring, and (2) add nutrients to the waters above and in Black Lake, being supplied by decaying pink salmon carcasses. Five pink salmon marked with orange plastic spaghetti in dorsal fin were seen on 8-28 and six were seen on 8-30-85. We were struck by the small size of pink salmon in the stream this year. 4. Mammal observations, spring, 1986: (fall, 1985 conditions were re- ported earlier in the interim report). Recent heavy rains contribut- ing to heavy snow melt and moderate flood conditions precluded ex- tensive tracking. Black Bear Creek was free of ice and no snow re- mained in the valley below the falls, but high water obscured the muddy streamoanks so frequently scrutinized in the past for evidence of mammal passage. Due to time and logistical constraints, no attempt was made to traverse the upper basin of the South Fork, where, seen from a helicopter flyover, winter conditions still prevailed. In light of these poor tracking conditions, mammal observations were con- fined to a cursory inspection of the main stream channel leading from the falls to Black Lake, and incidental to foot travel required for the retrieval of the thermographs from their installation sites throughout the system. -16 - Black Bear : In this late winter-early spring environment, sedges and skunk cabbage, favored early forage for bears, were only b~ginning to emerge, No bear sign was noted. It is likely that black bears in the vicinity were still hibernating, or possibly feeding in estuarine biota dowstream. Otter: Otter tracks and scats were noted in several places near the Forks of upper Black Bear Creek, particularly by the junction of the West Branch of South Fork with Black Bear Creek, and on the dam im- pounding Lake Fork pond. Beaver: The focus of beaver activity, as in the past, continued to occur in and around Lake Fork pond. Recent dam repair and fresh alder and saillmonberry cuttings were observed around the perimeter of the pond and in Spring Fork adjacent to the pond. Several of the large scent mounds throughout the pond and periphery were recently pawed and scented, indicating current beaver presence. Limited beaver feed- ing was observed along the upper West Branch and along lower reaches of Black Bear Creek above Black Lake. The South Fork. pond continued to be abandoned, with no fresh sign seen on a hike around the dam and back stretches of the limited impoundment. The break in the dam re- mained untouched. Judging by the somewhat increased activity in the West Branch area - where this channel separates from the South Fork -it is possible that this area may be the next focus of beaver expansion. Several old dams occur in this area, and one of them appeared to have been par- tially reworked in the recent past. Birds: 2 Ouzels 1 Kingfisher 1 Bald Eagle 5 Common Mergansers· 1 Common Loon 2 Goldeneye -17 - Summary: Late winter conditions prevailed in the upper Black Bear Creek basin. No black bear sign was noted in sites known to be favored for early foraging. Beaver continue to populate the area and represent a dynaminc force in the manipulation of water move- ment and aquatic habitat. No emergence of salmon fry appeared to have occurred.