ESTABLISHING THE HATCHERY 



results in economical construction 

 and satisfactory operation. Time 

 spent in surveying possible sites be- 

 fore a final selection has been made 

 will pay dividends. Many failures 

 are traceable to a compromise in de- 

 sign features because of the cost dif- 

 ficulties involved. Selection of a 

 site on which favorable conditions 

 can be utilized will avoid excessive 

 costs 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 the ponds, build- 

 ings, and other structures required 

 for a modern hatchery. The ground 

 should slope gently from the upper 

 end of the site, which is below the 

 source of water, to the lower end, 

 where water is drained from the in- 

 dividual ponds into a convenient 

 watercourse. The main objective is 

 to select a site of suitable size for an- 

 ticipated need and of such topog- 

 raphy that ponds can be constructed 

 without moving or hauling an ex- 

 cessive amount of dirt too far. Any 

 good engineer can make a topo- 

 graphic 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. The 

 best material consists of approxi- 

 mately two-thirds sand and one- 

 third clay, but generally some com- 

 promise in quality has to be made. 

 It is good practice to have the soil 

 tested. If there is any doubt as to 



the porosity of the soil structure, 

 borings should be made to deter- 

 mine 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, as water follows 

 these formations readily with con- 

 siderable 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 (fig. 

 3). The shape of such a pond de- 

 pends entirely on the topography. 



It is not desirable under any cir- 

 cumstances to dam a stream to make 

 a pond, or to locate the pond where 

 it is subject to regular floods. The 

 best impoundments are supplied by 

 just-sufficient spring water to main- 

 tain the pond level, or are located 

 high enough on the drainage basin 

 that the water level is maintained 

 by runofl^ from surrounding land. 



In sections of the country where 

 rainfall is relatively high, as in the 

 Gulf States as far west as Louisi- 

 ana, the drainage area should be 

 about 5 acres for each acre-foot of 

 water in the pond. In those sec- 

 tions where rainfall is lower — as in 

 southeastern AVisconsin and south- 

 ern, central, and western Minne- 

 sota — the proportion of drainage 



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