in economical construction and satisfactory operation. 

 Time spent in surveying possible sites before a final 

 selection has been made will pay dividends. Many 

 failures are traceable to a compromise in design features 

 because of the cost difficulties involved. Selection 

 of a site on which favorable local conditions can be 

 utilized will preclude excessive expenditures and 

 impractical installations. 



After a suitable water supply has been located, 

 other details of site selection may be considered. The 

 area must be relatively flat and large enough to include 

 all the ponds, buildings, and other structures required 

 for a modern hatchery. The ground should slope gently 

 from the upper end, which is slightly below the source 

 of water, to the lower end, where water is drained from 

 the individual ponds into a convenient watercourse. 

 The main objective is to select a site of suitable size 

 for anticipated need and where topography is such that 

 ponds can be constructed without moving or hauling too 

 far an excessive amount of dirt. Any good engineer can 

 make a topographic survey to determine the feasibility 

 of constructing a pond system on a piece of land. 



The most satisfactory ponds are constructed on 

 impervious soil. Clay soils or soils with a high clay 

 content are most desirable. fl?he best material consists 

 of approximately two-thirds sand and gravel and one- 

 third clay, but generally some compromise in quality 

 has to be made. It is good practice to have the soil 

 tested. I f there is any doubt as to the porosity of the 

 structure, borings should be made to determine the depth 

 of the impervious layer. Care should be taken that 

 there are no rock strata reaching the surface or beds 

 of gravel anywhere in the pond bottom. Water follows 

 these formations readily with considerable loss to the 

 pond. 



Where an extensive pond system is not desired, 

 small impoundments for the propagation of minnows may 

 be located in an area much more restricted than a 

 hatchery-pond system would require. These ponds may 

 be located in a natural gully where the land slopes 

 from three directions into the pond area and where the 

 dam will be neither so long nor so high that the cost 

 of construction will be excessive. The shape of such 

 a pond depends entirely upon the topography. 



It is not desirable under any circumstances to 

 dam a stream to make a pond or locate the pond where 

 it is subject to regular floods. The best impoundments 

 are supplied by just sufficient spring water to maintain 



