70 BULLETIN 414, TJ. 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- 
plies 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 surface; 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 springs 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 pollution from the camp 
itself, and unless its purity be safeguarded properly it may shortly 
become unfit for use. This pollution 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 sources, 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 liquids 
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 around 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 all water should be taken from the overflow- 
pipe. If the spring water be used for the cooling of food, a separate 
box should be built especially 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 supplies in limestone regions are subject to pollution 
carried from distant sources through the fissures and crevices in 
