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HomeMy WebLinkAboutKing Cove Hydroelectric Project Feasibility Study 1984- - KIC 006 KING COVE HYDROELECTRIC PROJECT FEASIBILITY STUDY CONTINUED FIELD INVESTIGATIONS OF DELTA CREEK AQUATIC BIOLOGY AND HYDROLOGY Prepared for: ALASKA POWER AUTHORITY Prepared by: DOWL ENGINEERS May 1984 · .. 0.10llns81 900 ::>DI • ll.lYQ TABLE OF CONTENTS PROJECT DESCRIPTION •.•....••••..•..•..••....•.•.•••...• STUDY BACKGROUND AND SCOPE OF WORK .•.•..••...•.•..••••• PHYSICAL DESCRIPTION OF THE CREEK ..•••••..••.••.....••. Section 1 Section 2 Section 3 .......................................... 1 1 6 8 9 9 HYDROLOGY . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 FISHERIES • . . • • . • •• • . . . • • • . • . . • • . . •. . . • • • • • . . . • . • • . . • . . • 11 Spawning & Rearing . • • . . . . . • . . • • . . • • . . • . . • . . . . . . . . . 14 CURRENT UTILIZATION OF FISHERY RESOURCES •• . . .. • • . . • • . .. 19 FISHERY IMPACTS • • • • . . • • . • • • .. • • • . • • . • • • • • • • • • . • • • • • . • • • • 20 PUBLIC REVIEW NOMINATION FOR WATERS IMPORTANT TO ANAD- ROMOUS SPECIES . . . . . . . . . . . . . . . • . . . • . • . . . . . . . . . . . • . . . . . 21 REFERENCES . . . • . . . . . . . . . . . . . • . . • • . . . . . . • . . . . . • . • • . . . . . • • 21 Figure 1 2 lIST OF FIGURES Project Location Map Schematic Diagram of Delta Creek System ••.••. 2 7 LIST OF TABLES Tables 1 Water Quality Data, 1981/82, Delta Creek ...••. 12 2 Delta Creek Estimated Total Pink and Chum Salmon Escapements . . . . • . . • . . • • • • . . . • . • • • • • . . . 1 3 ' 3 Species and Numbers of Fish Caught in Delta Creek . • . • . • • . . • • • . . . • • . . . • • • . . . • . • • • . . • • • •• .• 15 4 DOWL Stream Counts, 1982 •••...•..••.•...••••• 17 LIST OF PHOTOGRAPHS Photographs 1 2 3 looking Downstream at Proposed Dam Site ...... Clear Tributary .............................. . Glacial Tributary •.•...............•.......... 4 4 5 CONTINUED FIELD INVESTIGATIONS OF DELTA CREEK AQUATIC BIOLOGY AND HYDROLOGY PROJECT DESCRIPTION The Alaska Power Authority has proposed the construc- tion of a small hydroelectric project on Delta Creek north of King Cove, Alaska. A diversion weir is proposed to be constructed across the creek, at the 400 foot elevation 1 e v e 1 • W at e r w i 11 then be d i vert e d into a pens to c k , wh i c h will lead to the powerhouse located downstream. The power capacity will be 575 kilowatts. A transmission line will lead from the powerhouse to King Cove. A road will be con- structed from the airstrip to the powerhouse, and on to the diversion weir. A project location map is provided in Figure 1. STUDY BACKGROUND AND SCOPE OF WORK DOWL Engineers initially contracted with the Alaska Power Authority to provide environmental studies including a two-day reconnaissance visit, followed by a three-to four- day trip for more detailed studies. A literature review and discussion with local residents and agency members were to be combined with field studies to obtain information on fish and wildlife resources in the area and potential effects of the project on these resources. cu - II) en c: .S! 01 II) c: z 0 cu > -Ci Q. !i u; E c: c z E .S! en <t c ->- 0 u _J cu ·= a.. ""C en c X cu ::J II) E 0 w 0 Q. c .... 0 cu cu .... ... -a.. -c en ;t ' E9 cu -cu ::J II) 0 ::J a:: 0 .c 0 .... cu ~ ~v1- 0 a. " ""C cu II) 0 Q. 0 .... a.. • ~\ ~ i .X u 0 w a:: :::::> (!) LL... Q_ <( ~ z 0 ~ u g r-u w --:> 0 0::: Q_ ~ w w z lJ z w Hydrology, land status, archaeologic and/or historic sites, and permitting requirements were to be briefly dis- cussed, as well as impacts on recreational values, air quality, socioeconomics and scenic viewpoints. The initial reconnaissance t ember 1 7-1 8 , 1 9 81 , and a more took place October 12-16, 1981. site visit occurred on Sep- detailed site investigation Delta Creek was walked from the airstrip to above the dam site with minnow traps selec- tively placed throughout its length. Photos 1, 2 and 3 show the proposed dam site and the two tributaries to Delta Creek above the dam site. Numbers and locations of wildlife, and wildlife sign, were noted. Local residents were contacted through a community meeting on September 16, 1981, and through discussions with individuals during both visits. The Alaska Power Authority held an information meeting to discuss four potential hydropower sites, including King Cove, with interested federal, state and local organizations in Anchorage on October 21, 1981. Additional contacts with state and federal resource agencies were made by DOWL on an individual basis during September, October and November of the same year. Following an April 28, DOWL, Alaska Power Authority, 1982 u.s. interagency meetinq with Fish & Wildlife Service and Alaska Department of Fish and Game, the scope of work was amended to include two additional trips to King Cove in August and October of 1982. This report incorporates the results of these further field investigations at Delta Creek during the fall of 1982, as well as updating some of the -3- - No. 1: Looking downstream at proposed dam site. No. 2: Clear tributary No. 3: Glacial tributary previously supplied data on project stream flows. recent site visit took place on January 8, 1983. The most PHYSICAL DESCRIPTION OF THE CREEK Delta Creek is groundwater supply. the two tributaries Dutton tributary is fed both by surface run-off and by The creek is glacially fed by one of from Mount Dutton; the other Mount clear and does not carry glacial debris. The proposed diversion weir site is below the junc- tion of the glacial tributary and the clear tributary. The main stem of Delta Creek continues for approximately three- fourths of a mile to an area with less gradient near the city airstrip. There the channel breaks into meanders and drops its heavy glacial sediment load. The powerhouse would be located above the meanders on the main stream channel. One tributary, Airstrip Creek, contributes flow from a swampy area, apparently part of a groundwater system gather- ed from the aquifers in the surrounding mountains. This tributary flows into one of the meanders. The river again forms a main channel before the North Tributary joins it near the Delta Creek outlet at Lenard Harbor. The total river mile distance from proposed weir to the harbor is approximately six miles. Figure 2 provides a schematic diagram of Delta Creek and its tributaries. The heavy sediment load of the glacial tributary above the weir will be an important consideration for the diver- sion weir design. Much of the sediment is picked up from the channel banks by the high surface water velocities. In general, the change in gradient and flow velocities cause much of the sediment load to be dumped at the meander area -6- MOUNT DUTTON North Tributary estimated mean onnuo I flow: \ \ Delta Creek estimated mean annuo I flow: 3 90ft. /sec. >-a:: ~ :::> m a:: 1- J: 1-a:: 0 z KING COVE + c;ffi)ENGINEERS SCHEMATIC DIAGRAM OF DELTA CREEK SYSTEM Upper De Ito Cr. estimated mean annua I f I ow: 24ft.3 /sec. 1PROPOSED POWERHOUSE AIRSTRIP CREEK FIGURE 2 below the proposed powerhouse. Approximately 70 percent of the sediment load is carried from late May to early Octo- ber. Design of the weir facility must include a method for dealing with heavy sediments and the likelihood of load dis- charge at the weir site instead of its usual discharge near Airstrip Creek. The Creek can be divided into three sections (see Figure 1): Section One includes the Glacial and Clear Tribu- taries, their confluence, and the main stream to the pro- posed powerhouse site near the airport: Section Two runs from the proposed powerhouse to the joining of Airstrip Creek; and Section Three runs from Airstrip Creek to Lenard Harbor. Section One has no historical use as navigable water and does not appear to be navigable. The lower sec- tions may be navigable but residents apparently do not use the river for that purpose. Sect ion One, above the proposed powerhouse site, includes a clear tributary and a fast moving, turbulent and silty glacial tributary. The glacial tributary has no pools or backwaters and has large unvegetated areas on both sides indicating periodic high flows. It has a streambed of pebble gravel, cobbles and boulders, the proportions of which depend upon the location in or near the channel. The gravel is densely packed. The right clear tributary has less flow than the glacial tributary with a slightly lower velocity. Substrate is similar to that of the other tribu- tary but with more pebble gravel in the slower water. Algae grows in deep, low turbulence areas. Approximately 90 per- cent of the stream is composed of riffles and ten percent of pools. Vegetation reaches the waterline and little seasonal -8- fluctuation is apparent. The confluence of the two streams forms a stem of high velocity that flows around numerous small boulders. An unvegetated strip on both banks indicate periodic high flows. Section Two, including the river below the airstrip, is differentiated by reduced velocity and division of the creek into several channels. The area is marked by gravel bars with alder growing on law stream banks. The triangular channels are highly utilized by Dolly Varden juveniles who mature in the cobble to pebble size gravel. approximately one half mile long. This section is Section Three includes the meandering channel reformed by the secondary channels' confluence below Airstrip Creek. It runs approximately five miles to seawater at Lenard Harbor. The substrate includes a mixture of cobbles and pebble gravel near Airstrip Creek and pebble gravel at the mouth of Delta Creek. Smaller gravel and sand are also intermixed with the ather substrates. Stream banks are two to five feet in height and vegetated to the edge of the channel. HYDROLOGY Delta Creek, from its inception an the slopes of Mount Dutton to its discharge paint at Lenard Harbor, drains an area of approximately 14 square miles. Approximately 71 percent, or ten square miles, of the watershed is fed into the channel below the proposed diversion weir and powerhouse sites. -9- The North Tributary (see Figure 2) flows into Delta Creek two miles upstream from Lenard Harbor. This tributary originates in the same mountain range as Mount Dutton and is expected to have considerable orographically derived stream flows. Airstrip Creek drains the slopes of the mountains facing King Cove airstrip and flows into Delta Creek approximately one-half mile below the proposed powerhouse location. Airstrip Creek appears to be the groundwater dis- charge area of a regional groundwater flow system act inq in the area. It contributes surface water inflows to Delta Creek over a longer period of time than the other tributar- ies since the swamp at the airstrip area retains most of the run-off and then slowly releases it to the river system. Stream gaging has been continually recording data since January 1982, approximately one mile do wnst ream from the proposed weir. The estimated mean annual flow far that site has been verified to be 24 cubic feet per second (cfs) for the two and one half years it has been monitored. Flows for the lower tributaries downstream from the project site include an estimated 18 cfs for North Tributary, unknown for Airstrip Creek and a total flow discharge at Lenard Harbor of 90 c fs. Flows vary monthly (as recorded at the gaqinq station) results for the two gaged years have shown the following flows (in c fs) • Jan Feb Mar Apr May Jun Jul ~ Sep Oct Nov Dec 1982 15 1 3 19 32 53 32 60 94 46 26 30 22 1983 1 3 13 18 25 35 56 70 56 37 43 32 51 -10- The mean annual discharge for 1982 is 37 cfs and for 1983 it is 38 cfs. Turbine sizing is based on flows corresponding to the 35 percent (22 cfs) to 15 percent (44 cfs) range of exceed- ance values on the Delta Creek flow duration curve. During high run-off periods (usually spring, summer, and early fall), flows over 44 cfs will spill over the diversion weir and remain in the river. The penstock flow will return the full volume of water to the channel below the powerhouse. Limited water quality information is given in Table 1 (sampling locations are shown in Figure 1). The differing characteristics of Delta Creek tributary water above and below the proposed dam site are indicated by differences in both the temperature and pH. FISHERIES Pink, chum and coho (silver) salmon are known to spawn in Delta Creek (ADF&G, 1982). The Alaska Department of Fish & Game 1960-1981 escapement estimates for pink and chum salmon in Delta Creek are given in Table 2. They made no estimates for coho escapement in Delta Creek. Pink salmon escapement ranged from less than 100 to 20,000 during the 1960-81 period. Chum salmon escapement ranged from 1,500 to 31,000. Arnold Shaul, ADF&G Fisheries Biologist in Cold Bay when originally contacted in 1981, felt that the silver run in Delta Creek was probably small. -11- TABLE 1 WATER QUALITY DATA, 1981/82 D£I T A ~R~~I< Suspended Temp. Conductivity Turbidity Solids Date location (oC) pH (Micromhos/cm) (NTU (mg/1) - 10/12/81 Glacial Tributary s.o 5.1 290 100' above Pro- posed Diversion 10/13/81 Clear Tributary, 6.0 7.0 76 1 00 • above Pro- posed Diversion 12/12/81 Gaging Station 5.0 6.4 175 10/12/82 Gaging Station 1. 0 6.1 24 1/8/83 Gaqing Station 0.5 TARLE 2 DELTA CREEK ESTIMATED TOTAL PINK AND CHUM SALMON ESCAPEMENTS Year Pinks Chums 1960 200 6,100 1 9 61 <100 20,300 1962 <100 1,500 1963 <100 12,200 1964 <100 12,800 1 965 1 , 2 DO 7,000 1966 <100 2,800 1 96 7 <1 DO 4,800 1968 <100 9,500 1969 <100 3,500 1970 <100 10,500 1 971 <1 00 6,500 1972 <100 10,900 1973 <100 3,500 1974 <100 3,800 1 975 <100 2,500 1976 <100 7,500 1977 2,700 22,800 1978 8,700 25,000 1979 1 , 2 DO 2,500 1980 4,500 11 , 8 DO 1 981 1 '400 12,000 1982 20,000 31,000 1983 200 7,800 Source: ADF&G -13- No adult fish were seen during either site visit in 1981, but the stream was not walked in its entirety below the airstrip. With the exception of the glacial tributary, juvenile Dolly Varden were captured in minnow traps throughout the creek (Table 3). Two t r i p s we r e made to King Co v e in Aug u s t and 0 c to be r of 1982 by DOWL biologists to observe the upward extent of ad u 1 t sa 1m o n m o v em en t in De 1 t a Creek • These t r i p s we r e timed to correspond with peak spawning periods as verified through discussions with Arnold Shaul of Alaska Department of Fish and Game. The year 1982 was exceptional for both pinks and chums in this area of Alaska, with estimated escapements of 20,000 and 31,000 (Shaul, 1982). Local residents felt that the silver run was also larger than usual. Spawning and Rearing Chum salmon frequently spawn in the intertidal zone but will ascend short rivers. In Delta Creek chums primarily spawn in sloughs and backwaters near Lenard Harbor, but a few will spawn as far upstream as the airstrip (Shaul, 1981). Chums begin entering Delta Creek around August first and peak spawning occurs during the last 10 days in August and the first week in September. Pebble gravel ( .25 to 2. 5 inch), is reported to be the preferred spawning substrate for chums (Wilson et al., 1981). Optimum streamflow velocity and depth for spawning is 1.0 to 2.0 ft/sec.) and 1.0 to 2.5 feet respectively -14- TABLE 3 SPECIES AND NUMBER OF FISH CAUGHT IN DELTA CREEK October 12-13, 1981 Trap Location Juveniles Below the airstrip 4 Dolly At the airstrip 6 Dolly Above proposed po we rho use site 11 Do 11 y At the gaginq station 1 Dolly Between the staff qage and weir 1 Do 11 y Glacial Tributary 0 Clear Tributary 7 Dolly -15- Cau9ht Varden Varden Varden Varden Varden Varden ( W i 1 son , e t a 1 • , 1 9 81 ) . I m me d i at e 1 y up o n the i r em e r g en c e from the gravel, juvenile chum salmon migrate to saltwater. Pink salmon normally spawn intertidally or in the lower reaches of short coastal streams. Pebble gravel is pre- ferred, with an optimum streamflow velocity of 1. 0 ft./sec. and a depth of 0.3 to 1.5 feet respectively (Wilson et al., 1 9 8 1 ) • L o c a 1 r e s i d e n t s r e p o r t e d t h a t pi n k s s p a wn i n 1 o we r Delta Creek and in Airstrip Creek, a tributary stream which joins Delta Creek about three-quarters of a mile below the airstrip. Pink salmon begin entering Delta Creek at about the same time as chums with peak spawning also occurring d u r in g the 1 as t 1 0 day s o f August and the fir s t wee k o f September (Shaul, 1981). Like chums, pink salmon migrate to saltwater as soon as they emerqe from the gravel. Optimum conditions for spawning silver salmon are reported to be gravels of .08 and 1. 3 inches, depths of . 7 to 2.0 feet, and velocities of 1.5 to 2.5 ft./sec. (Wilson et al., 1981). Shaul had no information on where silvers spawn in Delta Creek but suspected they or near Lenard Harbor (1981). Shaul spawn noted in sloughs at that silvers probably begin entering Delta Creek the last ten days of August but did not spawn u n t il the 1 ate r part o f Sept ember and into early October. 0 n Au g u s t 2 5 , 1 9 8 2 , s t r e am co u n t s we r e co n d u c t e d o n Delta Creek from approximately one mile above Lenard Harbor to approximately one-half mile above the proposed powerhouse site (Table 4). The water in Delta Creek was highly turbid with glacial flour considerably limiting visibility. Visual counts therefore do not accurately represent total numbers -16- TABLE 4 DELTA CREEK STREAM COUNTS, AUGUST & OCTOBER 1982 Date August 1982 October 1982 Location Above the powerhouse Unnamed clear tributary across & below powerhouse Mainstem, powerhouse to Air- strip Creek Mainstem, Airstrip Creek to 1st riqht tributary (unnamed) Unnamed right clear tributary partial count Estimated carcasses Estimated fish in remainder of clear tributary Airstrip Creek to Lenard Harbor -17- Count 19 pinks 165 pinks 1, 250 pinks 13 chums 1,800 pinks 1, 500 pinks 1 silver 1,000 pinks 1,000 pinks 48 pinks of fish but can be used to judge relative abundance within the various stream segments. Delta Creek was waded upstream of the powerhouse so that fish movements would aid in in- creasing the accuracy of the count. On October 13-14, 1982, stream counts were again con- ducted on Delta Creek from Lenard Harbor to the proposed dam s it e • Two o b s e r v e r s , one on e a c h s t r e am b an k , we r e used • Visibility was considerably better than in August but was hampered by inclement weather and the type of habitat where silver salmon are typically found. The majority of salmon seen were observed in deep pools often in combination with undercut banks. Water depths ranged from 3 to 12 feet or more. Silvers probably hold and ripen in these pools before ascendinq smaller tributaries to spawn. No silvers were sighted above the junction of Delta Creek with Airstrip Creek but pools are uncommon in the upper sections, and those present are small and comparative- ly shallow (<3 feet deep). When first emerqed, juvenile silver salmon stay in gravelly shallows near shore. Older juveniles prefer deeper pools, and avoid riffle areas. They are strongly terri- torial and will defend their space from other juvenile cohos and salmonids. to Delta Creek. Juvenile silvers were found in tributaries in a 0.6 Dolly Varden spawn in fairly strong current to 2.0 feet (Wilson sm a 11 g r a v e 1 ( 0 • 0 8 t o 1 • 3 i n c h ) (1.0 to 2.5 ft./sec.) in depth of et al., 1981). Juvenile Dolly Vardens are relatively inactive, often remaining on the -18- stream bottom in pools or eddies under rocks and logs or undercut banks. Several schools of 10 to 30 juvenile Dolly Varden were observed below the proposed powerhouse in 18-to 22-inch deep pools near undercut banks. Dolly Varden occur in both anadromous and nonanadromous populations. If anadromous, juveniles spend three or four years in their natal stream before enterinq saltwater. CURRENT UTILIZATION OF FISHERY RESOURCES King Cove residents occasionally sport fish for Dolly Varden in Delta Creek. Approximately five years ago, a sub- sistence fishery for silvers began in Delta Creek. Although responses from local residents were somewhat contradictory, it appears that most of the long term residents do subsist- ence fish this run with catches of up to 100 silvers in one day reported. None of the residents contacted were aware of any use butary. occurs by silvers of the mainstream above the airport tri- Some subsistence fishing for pinks and chums also in Delta Creek. Subsistence salmon fishing also occurs on the west side of Cold Bay, where both silvers and sockeyes can be taken. Pinks and chums are taken in the King Cove Laqoon and in Ram Creek, to the southeast of town (Shaul, 1981). -19- FISHERY IMPACT Construction activity may temporarily increase erosion and sedimentation in Delta Creek. Sedimentation could affect fish by interfering with or preventing respiration by incubating salmonid eqqs, loss of spawninq gravel, and physical disturbance to both adult anadromous fish and resident species. This could result in a temporary disruption of salmon runs returning to Delta Creek. Proper construction techniques and timing should minimize this impact. The diversion weir will trap some of the coarser sedi- ments carried in Delta Creek, so that water released from the powerhouse will be carrying less sediment than before project construction. Diversion of flows will also reduce the bed load and velocity in the steam between the dam and powerhouse and may improve fishery habitat. The portion of Delta Creek between the diversion weir and the powerhouse may be dewatered during low flows and a major reduction in flow will occur during plant operations. This may prevent Dolly Varden from utilizing this stream section as they now do. However, several small tributaries join Delta Creek between the diversion weir and the power- house and this may partially offset the effects of flow diversion at the weir. -20- PUBLIC REVIEW NOMINATION FOR WATER IMPORTANT TO ANADROMOUS SPECIES Based on 1981 and 1982 field observations, conversa- tions with Alaska Department of Fish and Game biologists, and interviews with local residents, a recommended deletion has been provided under Alaska Department of Fish & Game's "public review nomination for waters important to anadromous species". Results of this nomination are pending. REFERENCES Alaska Department of Fish & Game. 1982. An Atlas to the Catalog of Waters Important for Spawning, Rearing and Migration of Anadromous Fishes, Southwestern Region 3. Shaul, A. 1981-1982. Fisheries Biologist, Commercial Fisheries Division, Alaska Department of Fish and Game, Kodiak, Alaska (personal communication). Wilson, W.J., et al. 1981. An assessment of Environmental Effects of Construction and Operations of the Proposed Terror Lake Hydroelectric Facility, Kodiak, Alaska. Instream Flow Studies, Final Report. Arctic Environmental Information and Data Center, University of Alaska, Anchorage, Alaska. -21- State of Alaska Department of Fish and Game Nomination for Waters Important to Anadromous Species Naill! ~ Waterway .,.~"11'"· _D_e_l_ta_c_r_ee_k _______ _ . . Year of Revision A roved AWCI o( Waterway __ 1_1o_o_.o _________ _ Regional Supervisor AWC Volume & Number Southwestern Region 3 USGS Quad Cold Bay. Alaska Addition Correction Deletion X Change X Drafted Change to X Atlas Catalog Both Spec1es Date(sl Observed Spawn1ng Rear1na Migrat1on Chum see Below X X X Pink see Below X S i 1 ver see Below X X X Comnents: Provide any clarifying ·information. including number of fish observed. location of fish survey data, etc. The area in question was walked and/or minnow trapped September 17-18; 1981; October 12-16, 1981; Augyst 24-2~. 19~2; and October 11-15, 1982. No adult sjlyec pink or cHum saimon.were seen .an no JUvenilel were caught above an apparent velocity barrier· in Delta Creek. The velocity barrier consists of a narrow chute through which Delta Creek passes. The chute exists near the upstream end of a berm constructed to protect the King Cove airstrip from Delta Creek. On September 11. 1981. Arnie Shaul, ADE&G Fisheries Biologist in Cold Bay stated that no spawning occurs in the area in question. Attach a copy of a map showing location of mouth and upper points of each • species. specific stream reaches identified for spawning or rearing; ·locations of barriers. such as falls. Attach a copy of the fish survey data. if available. Date: 5/10/84 4040 11 811 Street Anchorage, AK 99503 . ]\ ~ 'f' -·----1 ();' '*" , .. 'I v. 3 .. 10 \ ~ -I '"' ·~ "-. .., I . ' f&.o~t)' P~ak I I c-~ 8-3 . \ I •' ' l. l I ,I ( \' ·~ ... h D. -::k• J '' ) ., t:. ~-· -~~ J • · \ ) -I -I l sOool · ·~1 t • • · i· .LL ,, 0 c. ~~ () ) 0 .I ' \( ~ ' f-l. J ·' - I ,