IMPOUXDIXG WATER TO COXTEOL BREEDING OF MOSQUITOES, 19 



of a variable water level on marginal vegetation and marginal breed- 

 ing. This is obtained by a change in the water level from time to 

 time. This can be accomplished bv a sluiceway through the fill below 

 the level of the floor of the spillway. The flow of water through the 

 sluiceway can be controlled by a gate. If the sluiceway is placed at 

 the level of the bed of the bayou, in the center of the fill, it will act 

 efficiently in lowering or raising the water level above the dam, and, 

 also, the current of water through the sluiceway at this point will 

 flush out and carry away the mud and sediment that tend to accumu- 

 late in the bed immediately back of the fill. 



ADVANTAGES OF I3IP0UNDING, APART FROM PREVENTION OF 

 ANOPHELES BREEDING. 



A special advantage to the plantation, apart from the control of 

 Anopheles breeding in the baj'ou, is the fact that the impounded 

 water gives an ample supply of good water for the live stock through- 

 out the dry summer season. The land lying between the roadway 

 and the bed of the bayou is ordinarily used for pasture purposes by 

 the tenants living along the stream. Except in some instances where 

 clearing has been done in a comparatively wide strip of land found 

 between the road and the channel of the bayou, the pasture along the 

 stream is limited in extent and the grasses are crowded out by weeds, 

 bushes, trees, and vines. During the seasons of dry weather the 

 water in the natural bayou is shallow and stagnant. The supply is 

 often difficult of access by reason of the tangle of overhanging and 

 aquatic vegetation. The animals often become bogged in seeking 

 the water, and the more shallow and isolated pools are converted 

 into wallows, particularly where hogs are pastured along the bayou 

 side. The situation under these conditions is unsightly and insani- 

 tary and the supply of water is limited in amount and of the 

 poorest quality. With the limited pasturage the animals do not 

 thrive, and often die. The pasture for the plantation stock — that not 

 owned by the tenants — is the wet land lying between the cultivated 

 areas and the timber and swamp. These pasture lands extend into 

 the timber and the live stock depend upon the swamps and the shal- 

 low lakes in the basins of same for water. In any prolonged dry 

 season this supply becomes greatly restricted and as objectionable 

 in quality as that in the bayou. When this situation becomes acute 

 it is necessary for the plantation to drive wells throughout the 

 pasture areas and pump water. This adds greatly to the expense of 

 taking care of the stock. On Hecla plantation, following the clear- 

 ing of the section in Bayou Walnut and impounding the water, the 

 management not only extended the fencing to include the entire im- 

 pounded area, but also arranged the fencing of the pastures in one 

 section of the plantation so that by a system of gates the live stock 



