21 



Figure 9. — <;!oIlectiiig basin constructed outside the ponds. 



To every outlet box there is attached a kettle or 

 catch basin, which should be about 10 inches deep and 

 should extend above the bottom of the pond. Experience 

 has shown that most of the fish can be removed with a 

 seine as the water is being drained, but some receptacle 

 should be provided for the last few fish. The catch 

 basin and outlet combination should be set at the toe 

 of the levee and halfway down one side of the pond at 

 the deepest end. 



An alternative type of construction involves the 

 use of an outlet box and the catch basin at some point 

 outside the pond. The outlet box is similar to that 

 designed for a natural pond and does not require the 

 use of a screen. All the water is drained through the 

 outlet to a catch- basin outside the pond (fig. 9). 



The outside seining or catch basin is a concrete 

 1>ank constructed in such a way that water from the pond 

 outlet flows into it. Grooves are provided for a screen 

 and dam-boards. Where the outlet from the pond comes 

 into the seining basin, it is provided with an irriga- 

 tion gate or valve which may be shut when desired. 



780060 0-48-4 



