18 BULLETIN 652, U. S. DEPARTMENT OF AGRICULTURE. 



In the planning of gravity drainage districts the common Interests of adjacent 

 districts in securing good outlet facilities have long been recognized in all 

 parts of the country. Experience has shown cooperation between such districts 

 to be necessary. As yei mosl of the reclamation districts that secure drain- 

 age by pumping are independenl of each oilier, and. as pointed out above, those 

 Which are fortunately situated will remain so. On the other hand, interior 

 sections will eventually need better outlet facilities to the Gulf if the present 

 policy of developing small independent districts is continued. 



It is evident that the various districts should be so correlated that there 

 will be no interference between the different interests. This makes necessary 

 a general survey of this district, covering the topographic and hydrographic 

 features. A survey of this scope would show the probable future necessity of 

 increasing the present capacity of the natural drainage channels, or perhaps of 

 providing additional outlet channels for some of the more isolated sections. 

 It is quite likely that such additional channels could be used as commercial 

 canals, thus making them doubly valuable. The section of the country lying 

 between Bayous Lafourche and Terrebonne, in the parishes of the same names, 

 is an excellent illustration of an area that eventually will need better outlet; 

 facilities, parts of this area now discharging drainage water through Si) miles 

 of natural drainage channel to reach the Gulf. As shown by the gage at Lock- 

 port, the natural water surface in the swamps already has a large fluctuation, 

 and any further extensive reclamation will considerably increase this fluctua- 

 tion. 



The drainage of nearly all the land in the above-mentioned section is now 

 effected, and the owners of land now drained by gravity should cooperate with 

 those owning pumping districts to improve the main drainage channels or con- 

 struct new ones. The responsibility for improving and maintaining these main 

 channels rests equally on all land in this area, although the assessments for 

 the work would be made according to benefits. It would be far better to take 

 proper action in time to prevent loss due to poor drainage, rather than to delay 

 action until crop yields are decreased and land values depreciated. 



RlVEB OVEKFLOW. 



Like all delta regions, this one originally was subject to pei'oidic overflow. 

 The smaller floods of the Mississippi River were confined within the natural 

 levees that the stream itself has built up, but at irregular intervals of some 

 years great floods would cover practically all of the delta for months. As soon 

 as any serious attempt was made to bring this land under cultivation, levees 

 were built along the Mississippi River banks to protect the lands from overflow. 

 Finally districts were organized which included long stretches of river, and 

 millions of dollars have been spent in levee improvements. This expenditure! 

 with such Federal aid as has been available, has built a continuous levee 

 system on both banks of the river throughout its length in the district under 

 consideration. The levees have been increased in size as fast as the protected 

 land could supply the money. In the earlier years, owing to insufficient cross 

 section of levees and low grade line, crevasses were of frequent occurrence in 

 limes of high water. As more and more work was done on the levees a greater 

 degree of protection was secured, and now crevasses are rare, although the 

 levees are not yet up to the full height planned. However, the amount of culti- 

 vated land protected by these levees is increasing very rapidly, thus not only 

 enhancing the security for bond issues necessary to finish the levees, but also 

 increasing the revenue-producing power of the land to pay the annual tax to 

 retire such bonds. The agricultural developments of southern Louisiana, which 



