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HomeMy WebLinkAboutBlack Bear Creek Environmental Status Report 1985BLA 0\4 L !13 /? -4/f t( RECEIVED BY ALAS~t~ rc~· .. ;.~ /.UT~OP'TY ENVIRQN;M~ 12175 MENDENHALL LOOP ROAD. JUNEAU, ALASKA 99801 · (907l 789-9305 Environmental status report based upon ~·~ lS•~ er._4l., Lat·e Summer Visit to Black Bear Greek -1985 - Daniel ~. Bishop October 10, 1985 ENVIRONAID 12175 MENDENHALL LOOP ROAD. JUNEAU. ALASKA 99801 · (907) 789-9305 Late Summer Visit to Black Bear Creek -1985 - This interim report follows a vis·it to Black Bear Creek in the last week of August, 1985. The work and this report are guided by contract agree- ment with Harza Engineering Company dated 13 August, 1985. I. Thermograph data were recovered August 29 and 30, 1985. These data cover the periods between October 29, 1984 and July to August, 1985. Instrument 1090564, installed at the Spring Fork Site (SFS) had a cor- roded battery terminal and was replaced by instrument 1090553. It will be seen that these thermographs operated for as long as 302 days (the entire period since Oct. 29, 1984) at the 2 hour recording inter- val - a remarkable record. The.plotted data from these records is shown in Figure 1. One objective of establishing patterns of water temperature in upper Black Bear Creek is to compare estimates of powerhouse tailrace water (from about -20 ft.~ Black Bear Lake) with natural conditions.. Exam- ination of the records for 1984-85 shown in Figure 1 (258 to 302 days long} indicates the following comparison between the UWS ~0 feet be- low the surface of lower Black Bear Lake} and the Powerhouse Site (PHS) thermographs. Fall 1984: UWS 1 -2°C > PHS UWS 1 -2°C < PHS fluctuating according to whether the waterfall acted to cool or to heat water in the course of 1400 ft. aerated fall. u 0 .., 0: ::> .. < "' "" 0. iS .. "' w .. ~ '-' c .., "' "' .... < "' ~ i5 ... "' .., ... ~ 12 !0 12 10 ~· -2- Average dailv te::I:oeratures for three sites at and l~e:!iately t-elov Slack Bear Lalr.e, Octoc-er 1984 through AU?'J6t 1985. ,0 ti' 3. ·a ~.. ... 0 rj (J) 0· ... 0·. (;., . .Q ·~ . .G. ~ . .. 0 c;' <3 <::>." Q 0 " e·e·e·e -20 ft., Black Bear Lake (U",.'S) out lee, Black !ear Lake (BEL) Powerhouse Site (PHS) 0. ~ 9 : p 0 <S' " "' d 0.. 0 "' 0 "' <;i> G 0 i:,'b· 0 0 Q- i!; 0 'f ' I '0. Q ·0 •~' I a> p "' ~~ ~<'l:' 0::/ 0 ~aG-6 ·.~ r? 6 c;' ~, oo <!>'"' I ~ ' ¢ • 'c~ <>.J 0 ' -,' , __ , '.. ~ G ~-.... -... Q:~~-0-J""-.-~ ........... " ... / ~~ (; ~-. ~-~· .. ?j •,_. "(' • -• •-~ '•· " '-• '~ ," •. o·\a __ i a." ···,• 0 _ oi---''"'"'Qf-...r... __ _, __ ~cr-_,.. ~·,."J ~ ~ ---~-"c;:FG-"'"&--/ e,Ar' ....... ,......._ .SJ-.s::::L.-_,..' .. • "'-" , .... __ ,-..._ ..,------·- .· 'a~ C>-v.·" ... ..r-...... _ ......... "'·" NOV.l ~lb: DEC. AverB~?.P dailv ter.-oerarun~s for three sites~belcw Po"'·u-house Site. Black. B~ar Creek, Novetlber 1«:181.. through August 1995. ' /'\ JA.~. l ' ' ~ \. I _ .. , A J ... , '\ fEB.l a G $ · 0 MAR.l '----/'v- APR.l Vpper Bla:k Lake (UBL) S?r 1ng Fork Si.te (SFS) StreaD Gr.:~vel Si::e (SGS) ' I \ 1\ I J / ~ ~~"' \. I \ ( ... '\... ,"'\ ,"".t\.,' \,,...--\ ,' ~ ........ \.\ ( \... •, \ \ J ._:.;-:_·,..._ • • • • \ "' ,--·---~ .... ·~ - . \ , ' ·' '' .. ~ ... ' ,, -...... ..... / \.""" ;~.. / \J,., I \I 'IJ !'f-l.'i l r, " , ....... -./ ~"'\ /~/ ; /_/ \ ,r,' ..., "'-f " .J '' '' '•~ :'"' ~ ·, ,,, ,,, ,-v' ' ··~~:/· ' __ / ~~ ~ ''J ..... I .; './ \,_.t' ~,····~~~~~~~~~~~~~~~~~~TT~~~~~~~~ JUt-;£ 1 JULY l AUG. 1 SEP'I. l /-\ r, I " \''....-. I' I',_...'-~ ..._J I ,-_.-"' I ? ;.-......." -·- \ . ' ,, 1 ... , I .. , ' I "'' \.J ~ . ..:...._-. / ..._, / \ I' ,,..,.,... \. ''"' ... , \. I \.J \ ...-_, ~ ,, ....... NOV.l DEC.l JA~:.l FEB.l MAR.l APR. l ~.AY 1 JL'~)F: l JCLY l AUG.l SEPT. -3 - Winter 1984-85: UWS occasionally l°C > PHS UWS more often 1 -2°C < PHS Spring, 1985: Summer, 1985: (variable length of records) UWS up to 5°C < PHS As in earlier water temperature records, Black Bear Creek's falls exert a strong effect on downstream temperatures, which vary (partic- ularly in fall and winter) according to the season's weather, espec- ially the air temperature. The two groundwater-influenced temperature records (SFS and SGS} showed similar patterns. II. Adult salmon escapement counts were made on 8/28 and 8/30/85. These counts for sockeye and pink salmon are summarized along with compar- ative data from earlier years in Table 1. Sockeye counts for 1985 are consistent with those of earlier years. The absence 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 Bear Lake. Hatchery manager Steve Hansen reports that their counting weir operation began on July 19, 1985, at which time they estimated 55 sockeye were above the weir. Cumulative weir totals for sockeye are as follows: Date of Species Observation Black Lake to W. Branch 8/28/85 142 8/30/85 255 Sockeye 8/27/84 57 8/28/82 176 8/28/81 165 8/28/85 200 8/30/85 87 1984 Pink 1983 1982 9/16/81 I 121 Table 1: 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 J -----------1,752-------------I 1,267 ------------------ Lake Total Fork Count 3 783 -877 52 571 0 828 ~ 0 1,190 5 574 3 571 I 619 3,907 - 5 - July 19 55 sockeye (above weir) 29 108 Aug. 8 154 18 154 28 910 (most of these fish passed through on Aug 27-28) Sept. 7 954 17 1020 20 1039 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 Rlack Rear Lake (via Big Salt Lake, Black Bear Creek and through_ Black Lake) ar- rive on their spawning grounds one to several weeks before the Klawock Lake sockeye. It may be that colder temperatures for incuhation pre- vail in Upper Black Bear Creek than in the sockeye spawning stream(s) of Klawock Lake, requiring longer incubation periods in Upper Black Rear Lake. 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 regime 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 Bear Creek in sum- - 6 - 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. III. Lake profile measurements were made of the temperature and dissolved oxygen in Black Lake and lower Black Bear Lake on 8/28 and 8/29/85. These measurements have been superimposed upon graph composite sum- maries of data prepared for an earlier report. (Figures 2,3,4,& 5). Temperatures: Both Black Lake and Black Bear Lake water temperature profiles are seen to be near-to or on the low extreme for sunnner con- ditions. The thermocline in lower Black Bear Lake was located at 25 feet in late sunnner. Dissolved oxygen: Conversely, both lakes· are seen to have had very high dissolved oxygen in late s.unnner, 1985, and, again, dissolved oxygen in Black Bear Lake jumped up markedly between 25 and 30 feet. u 10- 0 Q) "" :I ~ cc "" Q) 3 -Q. m E-t "" Q) ~ co ~ 20 40 - 7 - 9/6/84 60 Depth. Feet 3/29/84 80 10/30/84 8/29/85 100 Figure 2: Profiles of Spring, Summer, Fall and Winter temperatures in Black Bear Lake. 1984 values emphasized; Fall, 1985 profile shown in red. t) • ~ "'" :I .u "' "'" ~ Q e ~ E-< "'" ~ .u "' 3. - 8 - 16 8 4 = ~~­ Ill ~= ~= Spring Sucmer Fall tVinter 10/29/84 3/26/84 0~-------.--------.--------.--------~------~-------- 10 20 30 Depth. Feet 40 50 Figure 3: Profiles of Spring, Summer. Fall and Winter temp~ratures in. Black Lak':· 1984 values emphasized;, Fall, 1985 profile shown in red. 6 . Q. . Q. I = ill 00 >. >< 0 ~ ill > r-f 0 Cl) Cl) .... Q 14 12 10 8 6- 4 2 3/29/84 20 40 - 9 - -~~ = Summer ~ = Fall ~:~,~1 • Winter 60 Depth, Feet 80 100 10/30/84 8/29/85 9/6/84 Figure 4: Profiles of Summer, Fall and Winter dissolved oxygen ·levels in Black Bear . Lake~,. 1984 values emphasized; Fall, 1985 profile shown in red. . a . Q, . Q, c:: CIJ eo >-~ "0 CIJ > ...... c Cll Cll ...t 0 -10 - ~ = Spring II • Summer ~ • Fall 14 \-linter 3/26/84 12 10/29/84 10 8/28/85 8 8/19/84 6 4 2 .0~---------r--------~--------~----------~------~ 10 20 30 Depth. Feet 40 ·50 Figure 5: Profiles of Sorin~. Summer. Fall and Winter dissolved · oxygen levels in Black Lake. 1984 values emphasized; Fall, 1985 profile shown in red. -11 - Both water temperature and dissolved oxygen profiles reflect below- normal temperature conditions experienced this summer in S.E. Alaska. IV. Mammal observations recorded during late summer, 1985 1./ Black Bear: two bears are currently residing in the study area, with the heaviest sign occurring in the vicinity of the upper West Branch and the South Fork pond, where approximately 30 pink salmon carcasses were found partially eaten on the stream banks. Track sizes (11. 8 em.; 9.6 em.) roughly correspond with tracks. of black bears seen here last November. The larger bear was seen on 30 August, grubbing at various roots in a marsh back of the West Branch of the South Fork. This bear appeared very healthy and sleek. Limited bear sign was noted on the Lake Fork due, in part, to absence of spawning salmon and generally poorer quality grazing in the herbaceous understory. As in the past, bear activity during adult salmon escapement is predominant in the junction area and up Spring Fork and South Forks, with unusually heavy trampling and feeding along the West Branch. Beaver: very little sign was encountered while paddling up Black Bear Creek from Black Lake to the West Branch junction, but here the sign be- gan. As reported in past years, beaver have created another surprise in the fall; this time on the West Branch of the South Fork. One old dam has recently been rebuilt to a height of 2 feet and a length of 40 feet, with a smaller dam (10 feet long) above the larger empoundment, serving to hold back the marsh. A considerable amount of fresh beaver sign oc- curs in this immediate area, with five new, freshly visited scent mounds filling the air with the odor of cas-toreum, even overpowering the smell of rotting salmon carcasses. In the immediately adjacent Spring Fork, some 30 meters upstream of the West Branch junction, beaver have built a small dam 18 inches high across Spring Fork, with fresh cuttings evident on both stream banks. ll This section written by Leigh Smith. -12 - The new dam on Spring Fork, reported summer of 1984, above the SGS thermograph site, is in a state of moderate disrepair with no fresh main- tenance work evident. South Fork pond continues to drain through the previously reported dam- break, with no beaver tracks seen on or near the pond margins. New veg- etation is rapidly encroaching upon the exposed pond bottom at a rapid rate. Lake Fork pond is stable and still an important hub of activity in the drainage, with fresh alder cuttings on banks· far behind the dam, and a small winter food cache is being assembled near the center of the pond - where such caches have been found every year of the study. The large scent mound near mid-pond is well-used and reeks of castoreum. In summary, beaver presence in the study area is undiminished, with characteristic activity-shifting still· in evidence, and no obvious dimin- ution of beaver population. West Branch activity is heaviest and fresh- est, with considerable dambuilding and feeding sign observed in the marshes south of lower Black Bear Creek above Black Lake. Otter: recent heavy rains had eliminated all but very recent tracks, but scats were observed at several locations along Spring Fork, at the mouth of West Branch, and on a partially submerged log in Lake Fork Pond. Marten: fresh tracks of one adult seen in the mud near South Fork Pond. Mink: due to recent heavy rains, no fresh sign was observed. Deer: no sign was found in the lower basin, but on 8/29 one doe was seen on a cliff 200 feet above Black Bear Lake. Fresh deer tracks were also observed near the mouth of Black Bear Lake. Deer population is estimated to be somewhat lower this year than last on Prince of Wales Island CHans-en, ADF&G, FRED).