142 FARM DEVELOPMENT 



Cultivating lands which drain into sloughs sometimes 

 results in so much less water seeping downward into 

 the slough that it does not thereafter need drainage. 

 The cultivation evidently results in more of the water 

 percolating into, and being stored in, the upper several 

 feet of the surface of fields and being from there trans- 

 pired back into the air by the rapidly growing plants, 

 which usually are more luxuriant than were the native 

 grasses or other native plants. 



Ponds, swamps and sink holes. Glaciers, in some 

 northern districts, in depositing debris, glacial water in 

 assorting and spreading out the solid materials, and 

 water from snow and rain where there was no glacier, 

 have caused many flat or saucer-shaped places to be 

 formed on the surface of the land. If beneath these low 

 areas there are layers of impervious clay, water accu- 

 mulates, making them too wet for the growing of cul- 

 tivated crops. Drainage through open ditches, tile 

 drains, or vertical drains, must be resorted to for the 

 removal of surplus water which accumulates in these 

 places. In some cases these low areas are so situated 

 that drainage is impractical or too expensive to be 

 profitably executed. 



Lake borders. Many lakes are bordered by lands 

 which lie at or very little above the level of lake water. 

 These may be drained by lowering the lake, or, in some 

 cases, conducting the surplus water away from the lake. 

 In many cases it is impractical to drain these lands. 

 The government holds that bodies of water of consider- 

 able size belong to the public at large and not to private 

 individuals. When the national government surveys 

 new territory preparatory to its settlement, all water 

 areas of considerable depth and size are carefully sur- 

 veyed and their borders are accurately mapped by the 

 surveyors. This surveying and mapping is called 

 " meandering," and no one has a right to lower the 



