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



becomes somewhat deeper during heavy and continued rains. There often 

 are periods of a month or two when the surface is dry. 



Experience in other districts has been such thai the locating of the reservoir 

 canal Immediately <>n the inside of the levee, using the material excavated 

 from the canal In building the levee, mighl be expected to give trouble in 

 causing a great deal of seepage through the levee into the canal. However, 

 because of the great width and height of tins levee the seepage is not noticeable. 

 The subsoil under this levee is rather better than usual. 



KESERVOIB CAN U.S. 



By using these canals as a reservoir it was necessary to construct only a 

 comparatively short canal into the interior of the district to give outlet to the 

 collecting ditches. These are mostly about 5 feel deep, with 10-foot top widths 

 and 3-foot bottoms, and serve as outlets for the small laeral ditches. 



Until the levee was increased in height in 1912, the canals had not been 

 cleared of silt since their construction, about 1S90. They had needed clearing 

 and deepening very badly for several years, as the water could not get to the 

 pumping plaid very rapidly after the level was reduced to about 2 feet 

 below the land surface. Moreover, there was very little reservoir capacity 

 available, and the canals had to be kept almost dry to afford a proper depth 

 of drainage. After the material was taken out of the canals to increase the 

 size of the levee they were of ample size. The pumping plant now can be op- 

 erated at nearly full capacity until the water in the canal is reduced, to a very 

 low level, and the water comes from the farthest portion of the canal quite 

 rapidly. Therefore it is not necessary to start the pumps so soon to take out 

 the small amount of water that collects from ground-water drainage. 



A considerable portion of the front of this plantation is high enough to drain 

 by gravity. A diversion canal should be run across the front of the property 

 so as to carry the water toward the eastern side of the plantation and thence 

 into a canal which leads to land about 1 or 2 feet above Gulf level. This di- 

 version canal or ditch should be connected with the outside of the district by 

 means of a self-acting sluice gate which would insure against water coming in 

 from the outside. The ditch would keep the water from the high land from 

 pouring rapidly back toward the lower land near the pumping plant as it does at 

 present. At times of very heavy rainfall a considerable area in the vicinity of 

 the pumping plant is flooded for periods of from a few hours to more than a 

 day. After most of the water from the higher land had been diverted outside, 

 the district gates could be opened in the lower side of the diversion canal so 

 that the low-water How could go back toward the pumping plant and allow 

 the canal to be drained completely. This improvement would save many flood- 

 inu r s of the lowest portion of the plantation and also a considerable amount of 

 fuel for pumping-planl operation. It is a feature which should be Investigated 

 very carefully when making a study of the best plan for draining lands of tins 

 character. 



DITCHES. 



The ditches on this plantation are of about the usual cross section on such 

 lands, having depths of 3 feet, top widths of .", feel, and bottom widths of 14 

 feet. The spacing Of the ditches varies with the character Of the land. Thus, 

 on the front lands, which are rather impervious, the spacing is about 100 feet, 

 while on the newer lands taken in from the prairie the spacing is from 200 to 

 ."<M> feet, (in the front lands the laterals between collecting ditches are about 

 2,000 feet long; small, considering the large slope of the land. Conditions on 

 similar plantations where the ditches are twice as long indicate that the laterals 



