Chief, North Pacific Fishery Investigitions EFFECT of Mcvary FIRST-STEP COFFERDAM on UP-STREAM MIGRATION of SALMON and STEEIMAD TROUT, 1948

UNITED STATES DEPARTMENT OF THE INT'RTIOR

FISH AND WILDLIFE SET@TCF Washington, D. C.

EFFECT OF McRARY FIRST-STEP COFFERD/N ON UP-33TREAN MIGE"ITION CF SALMON AND STEELFFAD TROUT, 1,*8

Joseph T. Barnaby Chief, North Pacific Fishery Investigitions EFFECT OF McVARY FIRST-STEP COFFERDAM ON UP-STREAM MIGRATION OF SALMON AND STEEIMAD TROUT, 1948

Introduction

An act of The Congress (P. L. 14, 79th Congress) 1945, approved March 2, authorized the Corps of Engineers to a dam Columbia (from construct across the River the Washington shore to the Orego7j shore) in the approximate vicinity of Umatilla, Oregon and specified that the dam, when completed, was to be known as McNary Dam in honor of the late Sena- tor Charles L. McNary of Oregon.

Subsequently funds were appropriated to the Corps of Engineers on to carry detailed planning and to start actual construction of the dam and its appurtenances. The plans for the initial construction vided a pro- for cofferdam to enclose a portion of the river on the Washington- shore side of the river. This cofferdam, being the two be first of or three to built during the course of construction of McNary Dam, is as the "first-step referred to cofferdam". Model studies were made of the structure at Bonneville and the contract for the construction of the cofferdam was awarded Guy to the F. Atkinson Company by the Corps of Engineers on October 30, 1947. The first-step cofferdam is to be in place during 1948 and!1949, the seasons of after which it is to be removed from the river. During the course of model studies of the cofferdam, was first-step It informally decided by personnel of the state fishery agencies Oregon and of Washington, the Fish and Wildlife Service, and the Corps of Engineers that this cofferdam would not seriously interfere with the upstream either or downstream passage of fish and therefore no fish-passage facilities need be incorporated in the In be structure. contrast it might noted that all Concerned expressed verbally the need for such facilities in connection with the second-step cofferdam.

Subsequently the Nez @erce and Yakima Indians endeavored an to obtain injunction against the Atkinson Company to cause them to cease and desist the construction of the cofferdam on the grounds that it would do serious and irreparable damage to tho Columbia River salmon populations and hence to the plaintiffs. At the hearing before the Federal Court Yakima, Pistrict in Washington on April 12-15, 1948 testimony was presented to substantiate this contention. Other testimony was also presented and at the conclusion of the hearing the Court denied the plaintiff's appli- cation, ruling that the evidence presented did not warrant the contention that the fish runs would be seriously and damaged e@f irreparably as a result the first-step cofferdam. Observ,itions at the Cofferdam

In order to have first hand knowledge in re.:,ard to conditions for fish passage, in the vicinity of the McNary damsite, the North Pacific Fishery Invostigzftions of the U. S, Fish and I.-ildlife 9orvico got, ilp 9 prnarqm of observations. Mr. Joseph Gailley, Fishery Biologist, was the principal observer, aided during the season by other members of the staff. The following by days, table gives, I the names of Fish and Wildlife personnel who made observations-

19 14 April - Holmes, Barnaby June - Gauley Juno l',) - Gauloy may 8 16 - Gauley, Barnaby June - Gauley May 9 . Juno 17 - Gauley May 10 ...... 18 B - Gailley June - Gauley, arnaby May 11 - GRuley June 19 - Harnaby May 12 - Gauley June 20 - Gailley May 13 Gauley - June 21 - Gailley May 14 - Cauley June 22 - Gauley May 15 - Gauloy, Burner, Lambert June 23 - Gailley May 16 24 . June - Gailloy May 17 ...... - Gauley June 25 - Gauley May 18 26 - Gauley Juna - Gauley Ma y 19 - Gauley June '7c May 20 28 ...... - Gauley Juno - Gauley Mav 21 - Gauley Jiuae 29 - Gauley May 22 - Gailley June 30 - Gauley May 23 May 24 ...... - Gailley July I - Gauley May 25 2 - Gauley July - Gauloy May 26 3 - Gauley, Burnaby July - Gailley May 27 4 - Gauley, Barnaby July . 28 ...... May - Gauley, Barn,,by July 5 Mc@y ...... 29 - Gauley July 6 Gauley May - N . July 7 - Gauley May 31 ...... 8 ...... July - Gauley July 9 - Gauley Junc I - Cauloy July 10 - Gauley P Juno - Gauloy July 11 - Gauley 3 Julie Gauley July 12 - Gauley 4 - June - Gauley July 13 - Gauley 5 14 June - Gauloy July - Gaulcy June 6 15 ...... July - Gauloy June 7 - Gauley July 16 Gouley 8 - June - Gauley July 17 . 9 18 ...... June - Gauloy July . 10 ...... Julie - Gauley July 19 - Gauley June 11 - Gauley IC- 18 June - Gauloy Aug. - Barnaby Juno 13 ...... The first-step cofferdam extends out from the Washington-sbore side of the river a distance of some 650 feet, or more than (Figure 1). one-third of the way across the river However, the main channel at that location is close to the Oregon shore so that the constriction of the river is not tip@preciable at flows below 200,000 second-foet. Further, owing to the nature of the Oregon shore it was the concensus that, regardless of river stage. that shore would always be. pmq-qq'n1P tion of interference with fish migration, then, resolved itself gcographi.- cally to the region adjacent to the cofferdam and hydrograPhically to periods when the flow was in excess of somo 200,00( second-fee't. Thr, Columbia River, as it passes the McNary dcmsite, is relatively muddy and objects a few inches below the surface connot be seen. This situation enhanced the problem of determining the extent to which fish were being held up as a result of the cofferdam. However, observations at other locations where water is muddy nnd where a partial or total block of fish Prevailed h@tve indicated that if any quantity of fish are present some of them will "surfaco" and can be seen at, that, time.

Messrs. Holmes and Barnaby visited the cofferdam on April 16 at which time the river flow was 120,000 second-foet. No fish were seen and it was obvious that the river currents were such that fish could easily swim upstream.

On May 8, Messrs. Gauley and Barnpby visited the cofferdam at which time the river flow was 285,000 second-feet. No fish were seen and it was rc@isonably certain that fish still could casily swim upstream. Mr. Gauloy was detailed at th--, McNary dnmsitc from May 8 until July 19. During this Period particular attention was paid to the area immediately adjacent to the outer face ruid below the lower leg of the cofferdam. If fish were being held up the Point of block would be in the vicinity of cell 7 (Figure 1 & 2) and fish should accumulate in the eddy from that point downstream

Despite observations virtually every day from May 8, to and includ- ing May 26, when the cofferdam was tamped, no salmon were ever seen in the force. In this connection it is significant to note (See Figure 3) that for a Period of over a weak prior to May 26, the river flow had boon in excess of 400,000 seconi-foot so that if a flow of that magni- tude caused a block there should have been an appreciable accumulation of fish.

As will be noted in Figure 3, the river flow increased rapidly and steadily from May 17 (flow 365,000 second-feet) until May 31 (flow 980,000 second-feet). On May P6, the Corps of Engineers, realizing that the cofferdam was about to be topped, opened the gates on cell 22 and allowed water to enter the enclosed area so as to have it full at the time tho cofferdam was topped.

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FIGURE 1.

FIGURE 2.-McNery fIrst-step cofferdom. (Photo. courtesy of Corps of Engineers) /000 17 900

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600

500

FIGURE 3.

FIGURE 4. Section of cofferdam, cell 22 c e the low in the center O f the picture. By the morning of May 27, the enclosed area was completely flooded and water was flowing over some sections of the upstream leg of the cofferdam and out over cell 22 (Figure 4) on the downstream leg (river flow 720,000 second-feet). At this time fish could enter the enclosed area through the gate openings. The river level immediately above the cofferdam was some six feet above the level of the water in the enclosed area, and the water flowing in over the upstream leg of the cofferdam cascaded down the 8 or 10 foot rock and cement slope in a thin sheet in such a manner that, in Gauley's and Barnaby's opinion, fish could not swim out over the upstream leg. No fish were seen during the day.

On May 28, about the same condition prevailed at the cofferdam except that the flow over the upstream leg was greater, being to a depth of 12 to 18 inches in the deepest places. During one and one half hours' observation, salmon were seen to jump 16 times in an endeavor to ascend the lower side of the upstream leg of the cofferdam. At this time salmon could easily enter the enclosed area either through the gate openings in cell 22 or over those sections of the lower leg of the cofferdam that were then inundated. However, once in the enclosed area the fish could not got out as the upstream leg of the cofferdam was impassable. All during the day, salmon w'ere seen jumping at the upstream leg in their endeavor to pass upstream. By May 29, the river flow had increased to over 870,000 second-feet and the flow over the upstream leg of the cofferdam was such that fish could easily swim over it. Despite continued observation Mr. Gauley did not see any further evidence of salmon either in the enclosed area or below the downstream leg of the cofferdam.

The river flow reached a peak of 980,COO second-feet on May 31, and on June 13, (flow 940,000 second-feet) started to decline at a nearly constant rate of from 20,000 to 25,000 second-feet per day. During the period of high river flow the river eroded a considerable amount of rock off a 765-foot section of the upstream leg of the cofferdam. This 'break" (Figure 5) was to a depth of 10 feet and provided an easy passageway for fish out of the enclosed area, Two small breaks also occurred in the downstream leg. When the river was dropping, wire screens were Installed on cell 22 (Figure 6) in the downstream leg and on June 25 work was started on repairing the breaks. By July 3 (river flow 475,000 second-feet) water was still flowing into the enclosed area through the break in the upstream leg and any fish within the area could easily swim out through the break. At this time most of this flow was passing out through the screens on cell 22. A small flow as still going out through the break In the lower leg; however, the flow was limited and in Mr. Gauley's opinion @-.hore was little cr no attraction for salmon to enter the enclosed area at that point.

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FIGURE 5. McNary first - stop cofferdam. Note from flow pattern, location of breaks in up and downstream legs. (Photo. courtesf of Corps of Engineers)

FIGURE 6. Screens on cc// 22. A

FIGURE 7. Inshore end of upstream leg of cof ferdam.

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6 400,000 By the morning of July (river flow second-feet) the, water level in the enclosed area was 'telow the level of the top of cell 22 and also below the level of the break in the lower leg of the cofferdam, There was a small amount of water seeping through the rocks of the lower leg, this water entering the dam through the break in the upper leg which was still 75 to 100 feet wide. Thus no fish could enter the enclosed a-irea r@lnqurp, nould still leave through the break in the upper leg. Repair work was continuing and by 2:00 P.M. the break in the upper leg was repaired and fish could neither enter nor leave the enclosed area. On July 11, pumps were started to remove the water from the enclosed and (the low- area. They were operated intermittently the lock excavation est part of the enclosed area) was pumped virtually dry by August 13, Mr. Gauley and Mr. Kershaw, Game Protector of the Washington State Depart- ment of Game, saw a few hundred chubs, shiners, carp, and bass in the, Most enclosed area. No salmon or steelhead trout were observed. of the fish were "scrap fish" and it was not considered worthwhile to salvage them.

Mr. Gauley concluded his observations at the cofferdam on July 19, at which time the river flow was 250,000 second-feet. It is significant that during the entire period he was there, the only time he saw any salmon was on May 28, when conditions were such that salmon could enter the enclosed area but could not leave it. It is realized that if block conditions did prevail at the outer face of the cofferdam just prior to the time it was flooded, the interval was so short due to the rapid rise of the river, as to make detection of the condition virtually im- possible. There was considerable turbulence and upwelling of the water around the outer face of the cofferdam just prior to the time it was flooded and though no evidence of a block appeared in the form of fish surfacing, conditions for the passage of fish were not favorable.

Bonneville and Rock Island Count

Dam A part of the salmon and steelhead trout passing Bonneville proceed up the main stem of the Columbia River and are counted again as they pass through the fishways at Rock Island Dam. In the case of chinook salmon and stoelhead trout, only small fractions of the numbers passing Bonneville are accounted for again in this manner due to commercial fish- img at Celilo Falls and to many of the fish returning to other spawning areas such as those in the Snake River. Hence little or nothing can be determined by a comparison of the counts of these species. However, a sizeable fraction of the blueback salmon passing Bonneville Dam are again accounted for at Rock Island and thus a comparison of those two counts should reflect any abnormal conditions for fish migration such as might occur as a result of the presence of the first-stap cofferdam in the river. In Figure 9 are presented the weekly counts of bluebacks Bonneville and Rock Island Dams. The most striking thing about at both 1948 this graph is the similarity of the two histograms. It took the

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C4 blueback run approximately two weeks to traverse the 320 miles from Bonneville to Rock Island Don, which interval is slightly less than the average clapsed time for negotiating this di stance. Thus, neither the oatteni of the two curves of abundance nor the time interval in- volved gives any evidence of a delay in the @rpstream passage of blueback-, during the 1948 scason.

Prospects for Fish Passage During 1949 Season

With th(; knowledge gained durJr-g 1.948 we can face the coming scason with much less apprehension of thL possibility of fish loss A tried first- step McNary cofferdam th,"n was felt just a year ago. In the spring of 1948, tentative plans wore made to cxcavatc, 0, ch!innel in the unstream leg of the cofferdam in the evont that it was flooded and fish were not able to pass over it. It is now definitely known that at, certain flows, when the cofferdata is floodod, the upstrp,'M leg is irapessabIc un.Lc:ss a channel through the 1,,,g exists. In view of the unusually he@,vy snow i)tich in all aroas of the Columbia watershed, a potential flood hazard definitely prevails and there is a real likelihood that the cofferdam again will be inundated. Plans,, therefore, should be made and the necessary equipment should be on hand to excav@@te a channel in the upstream leg if mid when needed. S@,MMARY -SD CONCLUS.IONS

The first-stop McNary cofferd@im wrap, in the ('@Ol url@bil, R throughout the mericd of the 1948 Salmon runs. 2. Biologists of trial Ft, h @,nd Wildlife Service mado! observations -@fl 'IL UIN, nl@"6 "'O Trier U0, U 1111c" @lnd ru-tor the sp--ing run-off.

3. Desrite Pilot constucnL daily obsurvrltlon3 during the Period when flows of over 28.5,000 s@Xcrd-fect Drevailcd, no evidence was obt!iined (exc@pt as noted below) of a cloudy in the fish i,.O.grp-AiGn ,is a rusult of tho pr.--,sonce o' th@@ coffordam in the river,.

11. For i period of @lpproximatoly two [email protected] imiediately subsequ4mt to topping of the ccffer&n, sa-mon could ente- t-lie enclosure but c,,yald not coritinue upstre@@r,. This ccr.dition torraincted where tho river flow ( md the flow over the upstromi leg of the cofferdcii) Increased to such an extont that fish could easily .wi-,.1 ovar the upstrem leg. It is considered th;,t only s. relatively few fish were effected in this mpnner ;@nd thit no deleterious effects re- sulted from such a slight delay in their migration.

5. III,-, Prolonged high river flow cauz@od a cut or break in both legs of the cofford=, porticul@irly the, upstreen 1(@.g.

6. The bronk in the upstream Jug of t@ie cofferdam facilitf@ted the exit of fish froTa the enclosed @,,rea, payticularly during the time when the river flow write decreasing.

If' there had not bc@en a break -n the upstre-ma leg of the cofferd@Lm, it would havc been necessary to excavate a chminel throu(,,,h it to pea-,-.1it the pussage of fish. 8. The unusually heavy snow p,,,,ck In ,.ll @xe@@s of the Colwubi,,.,. Rivc@r watershed prc@,,-,nts a poll-ential flood q,,znrd end the possibility that the coffor,@,,--i will be imindatkd ag in during the 1949 serison.

9. In view -f the pro-babi-Lity th@@t the cof." erd@a@., w@ll oe flo&[@@(l @:;",in, be ma(b it is that definite, plains mi(' - equ ipmcnt b@,, on hand to uxcavute a channel in thc upstr,@@,,ji leg in order to provide 1)@,,ssnCe foi: f1sh out of ttie enclosed vx6a.