70 BULLETII^ 414, U. S. DEPARTMENT OF AGRICULTURE. 



be made to ascertain that there are no probable sources of future con- 

 tamination which may be beyond the power of the camp officials to 

 correct. Chief of such sources of contamination are privies, stables, 

 barnyards, hog pens, pastures, and manured fields; and water sup- 

 pHes which can not be protected from the surface washings or direct 

 ground leachings from these sources should not be used. 



Springs. 



Twelve of the camps investigated obtained their water from springs. 

 As a rule, springs form excellent sources of water supply, since they 

 usually come from distant sources and are filtered through sand, 

 gravel, and soil before reaching the siu^ace; but occasionally they 

 may originate not far away, and in such cases the water is more likely 

 to be poorly filtered and easily polluted. Springs of the former class 

 usually may be distinguished by the fact that they show a steady flow 

 in both wet and dry weather and are not much influenced by the dif- 

 ferent seasons, while springs of local origin tend to disappear in dry- 

 weather and come up rapidly again immediately after a rain. 



Though spiings usually are of a high degree of purity in the absence 

 of human settlements, when one of them is adopted as a water supply 

 for a convict camp it may become subject to poUution from the camp 

 itself, and unless its purity be safeguarded properly it may shortly 

 become unfit for use. This poUution may occur by the seepage of the 

 liquid contents of a privy, cesspool, sink, stable or garbage pit 

 through the soil into the water vein, or by surface washings, from these 

 and other soinces, into the spring pool. 



Contamination by seepage can be prevented only by locating 

 the camp buildings, stock corrals, and other sources of pollution at a 

 sufficient distance from the spring to make sure that any hquids 

 which reach the ground water previously shall have become purified 

 by filtration through the soil. In general, none of the structures or 

 waste deposits should be located within a hundred yards of the spring 

 and, if possible, they should be located on another slope. 



For protection from surface pollution, the spring should be inclosed 

 in a brick masonry or concrete box provided with a pipe inserted 

 in the side for the overflow of the water; and as a further protection 

 it is advisable to dig a ditch on the slope above the spring, so as to lead 

 the surface water aroimd the spring and into the overflow, as shown 

 in Plate II. On no account should buckets or vessels be dipped into 

 the spring for filling, but aU water should be taken from the overflow- 

 pipe. If the spring water be used for the coohng of food, a separate 

 box shoiild be built especiaUy for that purpose; and water for other 

 purposes, such as the soaking of tubs and buckets, may be obtained 

 from the overflow a safe distance below. 



Spring water supphes in hmestone regions are subject to poUution 

 carried from distant sources through the fissures and crevices in 



