The characteristics of flow in the fishway entrance and in the 

 lowest two pools —'were studied under a variety of tailwater conditions 

 (Figures 13, ill, 15) • Flow patterns made with both the original 

 "flashboard" arrangement (Figure 2) and with the notched weirs installed 

 in 1937 showed only minor differences because the weirs are flooded 

 throughout most of the range of tailwater elevations at which shad enter 

 the fishway. The flow in the lowest pool and through the entrance was 

 remarkably uniform and lacking in turbulence. Velocities through the 

 entrance ranged from a maximum of 2.6 ft/sec. at a tailwater elevation 

 11 ft. (above mean sea level) to less than 0.5 ft/sec. at a tailwater 

 elevation of lit. 5 ft. (above mean sea level). The large curved rein- 

 forcements on each side of the entrance created an area with lower velo- 

 cities just outside the entrance (Figures 13> lh, 15) • 



SUMMARY 



There are a number of distinctive features of the fishway at 

 Lawrence and it is difficult to know which of these features are re- 

 sponsible for the success of the fishway in passing shad. The loca- 

 tion of the entrance certainly must play an important role. The rounded 

 form of the entrance itself and its position relative to the direction 

 of stream flow may also be critical factors. Equally significant may 

 be the low velocities (average 1 ft/sec.) and the lack of turbulence 

 with which the water flows through the entrance. There is no "jump" at 

 the entrance at the water levels existing when shad enter the fishway 

 and thusj the fish are completely in the fishway before any special ef- 

 fort to ascend is required. The size of the pools may be important 

 and the fact that the pools are usually shaded by the high walls should 

 also be considered. The rise from one pool to another is not great and 

 the relatively small volume of flow (approximately 10 cubic feet per 

 second) produces less turbulence than found in most fishways 



_/ The opening in the side of the second pool (Figure 9) was not made 

 in the model. It is not involved at tailwater elevations of 13 ft. 

 (above mean sea level) or lower and it has very little influence upon 

 the pattern of flow until tailwater elevations exceed 13.5 ft. (above 

 mean sea level). Its main effect is a reduction in the velocity of the 

 flow through the fishway entrance. 



