302 American Fisheries Society 



Build the ladder of sound and durable two-inch plank- 

 ing, of as long lengths as it is possible to use, and of the 

 widths shown on the drawing. Make all longitudinal joints 

 over the steps or baffles of the ladder. Bolt together 

 thoroughly at the junction of the horizontal part of the 

 ladder with the inclined part. This junction should be re- 

 inforced with wide iron plates as shown, as this is the 

 weakest place in the structure. Use plenty of spikes through- 

 out the entire construction. 



The drawing shows the inclined part of the ladder sup- 

 ported and held in position by a framework loaded with 

 rock. A better means of support would be masonry piers 

 in case the bed of the stream is rock or ledge, or pile trestle 

 bents in case the stream bed is soft. Whatever the method 

 used, the supports should be of such a character and should 

 be near enough together to securely hold the ladder in place 

 against the uplifting force of the water during floods. 



The upper and lower ends of the fishway must be kept 

 clear of all mud and drift and other debris, and open to the 

 passage of fish. In case sticks or stones are washed into 

 the fishway and become lodged in the pockets of the baffles, 

 these should be removed by hand through the openings be- 

 tween the cover planks. 



The cost of the structure will depend, of course, on the 

 height and character of the dam and other local conditions. 

 No general estimates can be made, but the following bill of 

 materials required in the case of a masonry or concrete 

 dam five feet wide on the crest and with a difference of 

 eight feet between the water level above and below the 

 dam, may be given as an example. In this it is assumed 

 that the pool below the dam is four feet deep and that three 

 supports like that shown in the drawing are required : 

 For fishway : 



438 lineal feet of 2 in. by 12 in. planking. 



225 lineal feet of 2 in. by 10 in. planking. 



2 bent iron plates 16 in. by \s in. by 5 ft. 



2 in in straps 3 in. by l /2 in. by 7 ft. 



X anchor bolts % in. by 12 in. 



40 bolts Ys in. by 3 in. Spikes as needed. 



