IMPOUNDED WATER. 
SURVEYS IN ALABAMA AND SOUTH CAROLINA DURING 
1915 TO DETERMINE ITS EFFECT ON PREVALENCE OF 
MALARIA. 
The investigation of the effect of impounded waters on the inci¬ 
dence of malaria, begun in 1914 and reported in the Public Health 
Reports, 1 was continued during 1915. Surveys were made of the 
following bodies of water: The pool of Lock 12 on the Coosa River; 
the pool of Lock 17, Black Warrior River; the pond of the Parr 
Shoals hydroelectric power plant; and the pond of the Georgia and 
Carolina hydroelectric power plant at Stevens Creek. The first two 
are in Alabama and the last two in South Carolina. In addition, a 
cursory survey, but sufficient for the purpose intended, was made of 
two ponds of water of the Tennessee Coal, Iron & Railroad Co. near 
Birmingham, Ala. Incidental to other work a survey was also made 
of three small ponds in Virginia. Practically this was a physical 
survey, as it was too late 2 for the biological survey to be satisfactory, 
though such a survey was carried out so far as practicable. 
It had been planned to make surveys of typical areas showing the 
following conditions: 
(1) An area to be covered, but as yet not covered, by a large pond 
and its environment, the dam to make the pond being in process of 
construction (or soon to be constructed). Comparison of this sur¬ 
vey of the locality in its natural condition, with subsequent sur¬ 
veys after the pond was filled, would give exact data on the change 
in conditions produced by the pond. 
(2) A pond in its first year. 
(3) A pond in its second year. 
The last two were to be selected in environments as nearly alike 
as obtainable, and these surveys were intended to determine the 
change in the pond from the first to the second year, as there was 
some reason to believe that this change might be considerable. Three 
suitable units were selected in Alabama. 
A physical survey of the ponds at Parr Shoals and Stevens Creek 
in February, 1915, however, had shown that they presented some 
1 Reprints No. 244, 248, and 257, U. S. Public Health Reports. 2 October. 
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