22 BULLETIN 1098, U. S. DEPARTMENT OF AGRICULTURE. 
cussion varied greatly at times, due to failure to make such provision. 
However, from this variable level which occurred, the experience was 
gained that such fluctuation in level operated as an aid in the control 
of the marginal vegetation which otherwise would have gained a foot- 
hold and would have required an expenditure for the maintenance of 
clean margins. The suggestions are made that the crawfish injury 
‘ean be prevented by a core wall through the center of the fill to 
either side and below the box of the spillway in the dam, and that a 
variable water level can be secured by a sluiceway, with control gate, 
through the fill and core wall. ; 
Advantages to the plantation from the impounding work, apart 
from the control of Anopheles breeding, are a permanent supply of 
good water for live stock during the dry season; an extension of the 
land available for pasture; the deeper and more extensive water of 
the impounded area, which offers a favorable place for game fish and 
thus furnishes a source of food; and the lake-like body of water which 
offers recreation to the plantation people and adds to the attractive- 
ness and value of the property. 
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WASHINGTON : GOVERNMENT PRINTING OFFICB : 1922 
