The Farm Pond 19 



built primarily for sport fishing, the engineering considerations for each 

 section of the country would be highly variable. 



United States Geological Survey quadrangle maps are very helpful for 

 locating sites suitable for ponds. These maps show 5- or 10-foot contour 

 lines on relatively small areas of land, so that it is possible to select on 

 these maps locations for dams on intermittent water courses, to outline 

 die pond shore line above each selected dam site, and to estimate the 

 approximate acreage of land sloping toward the pond site from which 

 surface water will drain into the pond. Once the prospective builder 



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Figure 2.2. A partially drained pond. The deep area near the center of the 

 picture was specially constructed to permit fish to congregate there in winter. 



has located all possible sites for his dam, then a local engineer experienced 

 in pond construction can look over the actual sites, select the best ones, 

 make test borings to determine soil strata under the dam sites, and plan 

 the dams and spillway structures necessary to handle the estimated runoff. 

 Many ponds have been built without engineering assistance, and some 

 of them have been successful. However, do-it-yourself pond building is 

 not recommended beyond the preliminary steps described above, because 

 of the close tolerances between the runoff water handled and the type and 

 size of spillway structure required for it. Thus, if the spillway is of the 

 wrong type or is too small, the first flood may wash away the dam. On the 

 other hand, if the watershed is not large enough in relation to the storage 

 capacity of the pond, the pond may be full or nearly full only in wet 



