Although a crude operation, it has passed 

 considerable nunabers of fish. The nunnber of 

 shad passed has increased progressively from 

 35 in 1952 to 15,076 in I960. To increase 

 efficiency, the present system could be con- 

 verted to an automatic operation, whereby the 

 complete trap is raised to forebay level and 

 the fish automatically released directly into 

 the exit flume. 



A pool-type fishway was installed in a 7-ft. 

 high dann on the Neuse River at Goldsboro, 

 N.C., in 1952; the estimated shad passage in 

 1953 was 440 fish (Walburg, 1957). 



A vertical, baffle-type fishway was conn- 

 pleted in I960 in the Little Falls Dam, Potomac 

 River, immediately north of Washington, D.C. 

 This fishway was designed to pass fish over a 

 maximum headwater-tailwater elevation of 9 

 ft. In the spring of I960, the fishway passed 

 resident species of fish^ but shad did not 

 migrate upstream to this structure. 



Most modern fishways have a collection 

 system or channel which collects fish from 

 one to several entrances and attracts them 

 to a single fish-passing facility. Collection 

 systems for shad should have a minimum 

 width of 8 ft. and a minimum water depth of 

 4 ft. Velocities in the system should not ex- 

 ceed 2 to 3 f.p.s. (feet per second). The en- 

 trance to the collection system should be at 

 least 4 ft. wide, preferably 6 ft., and have a 

 depth of at least 1 ft., preferably 3 ft. The 

 velocity through the entrance of the collection 

 system should be about 6 f.p.s. but should not 

 exceed 7 f.p.s. nor be less than 5 f.p.s. These 

 flows, which are usually more than required 

 in the fishway, can be maintained through dif- 

 fusion grates in the floor of the collection 

 system. 



Attraction of fish from a large river into a 

 comparatively small collection system is the 

 most difficult problem to overcome. Once it 

 has been accomplished, several nnethods can 

 be used to pass fish over a dam. The pool-type 

 fishway, consisting of a series of pools, each 

 higher than the next pool downstream, is prob- 

 ably one of the oldest. Fish ascend by swim- 

 ming against the water flow from one pool to 

 the next. For shad, the difference in pool ele- 

 vation should be 0.75 ft. Minimum size pools 

 should be 8 ft. long and 8 ft. wide, and mini- 

 mum water depth should be 4 ft. Size of pools 

 depends on the number of fish expected to use 

 the facility. The weir over which water flows 

 from one pool to the next can be full width or 

 half width or can have almost any arrangement 

 that allows adequate space for fish passage. 

 Each pool must be hydraulically balanced so 

 that there is no energy carryover by the 

 cascading water from one pool to the next. 

 Velocity in resting areas of pools should not 

 exceed 1 f.p.s. This type fishway usually re- 

 quires some adjustment with changes in tail- 

 water and forebay elevations. The adjustment 

 is made by having a level flume at the upper 



end into which stoplog baffles can be placed 

 to add additional weirs as forebay elevations 

 increase. 



Fish locks also are used in some areas for 

 passage of migrating fish over obstructions. 

 These structures are similar to boat locks. 

 At tailwater, attraction water is supplied 

 through the floor of the lock and flows out 

 through a gate into the tailrace. Fish are 

 attracted into the lock chamber by this flow, 

 and a trap device prevents them from leaving. 

 At regular intervals, or when sufficient fish 

 are trapped, the lower gate is closed and the 

 lock filled until forebay elevation is reached. 

 An upper gate is then opened, and the fish are 

 free to leave. To speed operation, a brail may 

 be used to force the fish from the lock chamber 

 into the river above. When the fish are out, 

 the upper gate is closed, the lock is dewatered, 

 the lower gate is opened, and the cycle re- 

 peated. Minimum size for fish locks and traps 

 for shad passage is 8 ft. by 8 ft. with a nnini- 

 mum water depth of 4 ft. Actual size of the 

 lock depends on the number of fish to be 

 passed. 



On the Pacific coast, several different types 

 of devices are used to enable shad to migrate 

 upstream past dams. Shad ascend pool-type 

 fishways at Bonneville, The Dalles, and McNary 

 Dams on the Columbia River to elevations of 

 40 to 90 ft. {U.S. Army Corps of Engineers, 

 1959). They probably would ascend higher danns 

 if fishways were installed. Fish locks in 

 McNary Dam also have passed shad, and locks 

 in Bonneville Dam were almost as effective 

 as the pools in assisting shad over the dam 

 (Talbot, 1953). Shad in the Sacramento-San 

 Joaquin Delta water developments in Cali- 

 fornia used in experimental vertical-baffle- 

 type fishway, the type first developed at Hells 

 Gate on the Fraser River in British Columbia, 

 Canada (Fisk, 1959). 



At the present stage of engineering and bio- 

 logical knowledge, the problenn of passing shad 

 over obstructions to upstream spawning areas 

 is not too difficult. The problem of safe pas- 

 sage of young and adults back downstream has 

 not yet been adequately solved, however. 

 Usually they must pass through turbines or 

 over spillways of the dam. Both means of 

 descent can cause considerable mortality. 

 Limited studies on migrant juvenile shad 

 through a system of canals by way of low- 

 head turbines at the Hadley Falls Dam on the 

 Connecticut River indicated that the fish de- 

 scended with little mortality -'■°. 



Progress in devising methods for safe pas- 

 sage of downstream migrant fish at dams 

 has not been very successful. Many guiding 



""•^ Unpublished report. Mortality of downstream migrant 

 juvenile shad, Holyoke Water Power Company canal sys- 

 tem, Connecticut River, 1957-59 by C. H. Walburg and 

 P. R. Nichols, Bureau of Commercial Fisheries Biologi- 

 cal Laboratory, Beaufort, N.C. 24 p. 



96 



