A fixed brail was installed in the flow 

 introduction pool to limit fish movement to 

 the upper 5 feet of this pool which has a 

 depth of 14 feet. Reduction of the pool 

 depth served to discourage the fish from 

 lingering unnecessarily in this area before 

 passing outward into the exit section and 

 back into the Washington shore fishway. 



Fishway Hydraulics 



Total water fall in the 96-foot fishway 

 was 6 feet (elevation 60 feet to elevation 

 54 feet). Standard water flows were con- 

 trolled to allow for 0.8-foot head (measured 

 4 feet upstream of weir) on the weir crest 

 which was the approximate upper limit at 

 which plunging flow could be maintained on 

 the Square-crested weir. When the fishway 

 was filled with water, the approximate water 

 volume per pool (accounting for the area 

 displaced by weirs) was 585 cubic feet. 

 Calculated discharge of the test fishway was 

 15.9 c.f.s. 



Two sources provided water for the 

 experiments: (1) a water supply system 

 originating in the Bonneville Dam forebay, 

 and (2) the exit fishway which received its 

 water from the Washington shore fishway. 

 Water balance within the facility was main- 

 tained by manual control of water intake 

 and discharge valves. 



Lighting 



A constant light condition was estab- 

 lished for all experiments. Sixteen 1000- 

 watt fluorescent mercury vapor lamps were 

 hung directly over the area in the test 

 fishway. As a standard, all light assem- 

 blies were set arbitrarily at 6 feet above 

 the water surface. This provided an average 

 light intensity comparable to that which 

 might be found in an outside fishway on a 

 bright, cloudy day. Readings obtained 

 directly under lights at the water surface 

 averaged 850 foot candles. The range of 

 incident light was 350 to 1000 foot candles. 



METHODS 



Experimental Approach 



Our approach to the solution of the 

 question, "What is the capacity of a fish- 

 way?" has been based on the belief that 

 the condition can be physically demonstrated 



by the introduction of varying quantities 

 of fish into a given fishway. Thus, by 

 gradually increasing the numbers of fish 

 introduced in each experiment, eventually 

 an end point or boundary indicating maximum 

 passage per unit time would be reached. 

 Since there is no way to anticipate the par- 

 ticular point at which this will occur, it 

 will be necessary, therefore, to extend the 

 fishway beyond a hypothetical capacity in 

 order to examine the particulair reactions 

 which might develop as a result of an over- 

 crowded condition, if such develops. To 

 demonstrate this condition, the first and 

 most importEint requirement will be to main- 

 tain a constant supply of fish in excess of 

 the maximum the fishway would be capable of 

 passing per unit time — at least for a period 

 long enough to establish that certain funda- 

 mental relationships are characteristic of 

 a saturated or possible overcrowded fishway. 



The foregoing approach will lead to the 

 examination of the following concepts as 

 they are applicable to the determination of 

 capacity in an overfall, pool-type fishway: 



1. The initial factor limiting the 

 capacity of any fishway is the maximum num- 

 ber of fish that may enter per unit time. 

 Among the factors which may affect maximum 

 entry are (a) passage space, (b) entrance 

 hydraulics, and (c) differential motivation 

 among the fish on different days and within 

 the same day. 



2. Maximum exit per unit time (capa- 

 ity) can equal maximum entry per unit time. 



3. Once a maximum entry is reached and 

 maintained, the rate at which fish ascend 

 the fishway will govern the extent to which 

 they will accumulate in the fishway per unit 

 time. This accumulation will mount arithme- 

 tically as the rate of movement decreases. 

 For instance, if entry is established at a 

 maximum of 40 fish per minute and fish ascend 

 the fishway at an average rate of one pool 

 per minute, then 40 fish will be the average 

 number present in each pool. If the average 

 rate of movement decreases to an ascent of 

 one pool every two minutes or one pool every 

 three minutes, then the accumulation in each 

 at a given minute will be 80 and 120 fish 

 respectively. Exit in each instance will 



be 40 fish per minute. As long as the accu- 

 mulation resulting from a particular rate 

 of movement in combination with a fixed 

 maximum entry rate does not impair "free" 



