22 BULLETIN 71, U. S. DEPARTMENT OF AGEICULTUEE. 



root of the area. Thus, if the cost for levees on a given district is $10 per acre, 

 the charge on an area four times larger and of the same shape would be $5 

 per acre. Moreover, the doing of work along broad lines and the handling of 

 earth work in large quantities would reduce somewhat the unit costs of con- 

 struction. A levee location along the coast would have the advantage of a more 

 or less continuous chain of islands, some of which are never overtopped by 

 high tides, and many of which are nearly high enough at present to prevent 

 overflow. That such a levee would not need to be as high, in order to keep out 

 all tides, as one farther inland is proven by the high-water records of the storm 

 of 1009. and those of earlier storms ; this fact is also shown by the action of 

 the natural levee along the coast of Vermillion and Calcasieu Parishes. By 

 inclosing large natural depressions, such as bays and salt-water lakes, a consid- 

 erable reservoir capacity could be secured by regulating the stage of water in 

 them through the use of gates and locks in the levee. This would form basins 

 into which the main drainage channels of the interior could discharge. A levee 

 in such an exposed location must necessarily be capable of resisting the direct 

 action of the waves, and steps would have to be taken to check the present cut- 

 ting away by the Gulf currents of these natural levees. The oyster and fish in- 

 dustry of this portion of the coast would be greatly affected, as practically all of 

 the oyster beds would be inclosed by such levees. However, if the proportion of 

 salt water could be so regulated as to insure safety to the oyster beds the 

 plan would be of benefit to the industry, as it would protect them from the 

 damaging action of storms. The inclosing of such bodies of open water as 

 Timbalier or Terrebonne Bays would not entirely eliminate storm tides in them ; 

 Lakes Ponchartrain and Maurepas, although well inclosed by the natural land 

 surface, showed strong tidal action during the storm of 1909. 



DESCRIPTION OF RECLAMATION DISTRICTS. 



Previous to about 1907 there had been no active movement in the drainage of 

 the wet prairie lands of Louisiana. The older plantations had extended their 

 clearings back to the belt of cypress swamp that usually lies between the ridge 

 along the Mississippi River and the grass-covered prairie; there, owing to the 

 expense of clearing such land, further progress was usually checked. At some 

 points, however, where this belt of timber was narrow, the plantations have 

 been extended to include relatively small areas of prairie land. Such areas 

 were inclosed with levees, ditches were cut, and pumping plants installed. The 

 land thus reclaimed on such a small scale has proved to be very fertile and has 

 been farmed with entire success. About 5 years ago the present movement for 

 reclaiming large areas of wet prairie land began, and districts consisting 

 entirely of wet prairie land were inclosed by levees and drainage systems 

 installed. The degree of success attending these early reclamations interested 

 people from many points outside as well as within the State, and at present the 

 work is being prosecuted with an ever-increasing vigor. From the drainage 

 engineer's standpoint the work has passed the experimental stage, and by fol- 

 lowing the best methods used on existing districts the successful drainage of 

 the average type of wet prairie land seems assured. However, owing to the 

 comparative newness of the work, many problems have yet to be satisfactorily 

 worked out. 



The degree of success attained in the various methods used in the reclamation 

 of these lands has been quite closely investigated by this office. This investiga- 

 tion has included studies of the natural features of a number of drainage dis- 

 tricts and of the levees, reservoir canals, field laterals, pumping plants, and 

 methods of cultivation, as well as the records of rainfall and run-off. A large 

 number of districts have been examined closely, and practically every district 

 within the State has been inspected. 



