POND CONSTRUCTION 



FiGUBE 3. — Pond located in a natural gully, using runoff as a source of water. 

 (Photograph courtesy of the U. S. Department of Agriculture.) 



area should be greater. It is par- 

 ticularly desirable that drainage be 

 from good pastureland, a stable for- 

 est area, or other well-covered land. 

 Eroded or improperly tilled soils 

 allow rapid runoff, which results 

 in silty waters and gradual filling 

 of the pond. Some operators who 

 must take waters from tilled land 

 construct a small settling pond or 

 silt basin above the regular pond. 

 The lower end of the pond site 

 should be of sufficient width to pro- 

 vide an adequate auxiliary spillway 

 to carry off occasional floodwaters 

 (fig. 4). 



Pond construction 



The da/in. — Small impoundments 

 are generally made by building a 

 dam across a narrow gully where 

 the banks are of sufficient height to 

 provide water deep enough for fish 

 (luring winter. The depth at the 

 dam should be from 5 to 15 feet, de- 

 pending on the severity of winter 

 weather and the topography of the 

 pond bottom. In northern Illinois, 

 the depth should be at least 10 feet; 

 the farther north the pond, the more 

 this figure should be increased. 



First consideration is given to 



POND 





BAD 



Figure 4. — A spillway with a flat design, as on the right, is less likely to wash out 

 when heavy rains come than is the badly designed, V-shaped spillway on the left. 



