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THE IRRIGATION AGE. 



IRRIGATION AND DRAINAGE 



By Samuel H. Lea, State Engineer of South Dakota.* 



Irrigation in the United States is largely confined to 

 the great region situated west of the Missouri River. This 

 area includes the western portions of North and South 

 Dakota, Nebraska, Kansas and Texas, all of Montana, Wyom- 

 ing, Colorado, New Mexico, Idaho, Arizona, Utah and 

 Nevada, the most of California, and much of the eastern 

 portions of Washington and Oregon, and a small portion 

 of Oklahoma. 



The aggregate area embraced in this list is about 1,- 

 260,000 square miles, equal in extent to thirty states the 

 size of Ohio, or about two-fifths of the continental United 

 States. 



In this immense area there are now in operation, under 

 construction and projected many irrigation projects of 

 various degrees of importance, ranging from the small in- 

 dividual diversion works to the great projects of the United 

 States Reclamation Service. The expenditure of many 

 millions of dollars has resulted in the reclamation of vast 

 areas of arid lands, transforming barren wastes into green 

 fields yielding bountiful harvests. 



As a rule the irrigation of land is effected from flow- 

 ing streams, the water being diverted from the channel and 

 conveyed over the land through ditches, flumes and conduits. 

 In some cases reservoirs are prepared for storing the water 

 when it is not required for immediate use, thus utilizing as 

 nearly as practicable the full flow of the stream. Other 

 systems of irrigation comprise pumping from a stream or 

 lake or from an underground source of supply. 



The area of land under irrigation is constantly increas- 

 ing and in course of time the limit of water supply available 

 for such use will be reached. This is already the case in 

 some sections and the problem confronting 'the irrigator 

 under such a condition is where to obtain a supply of 

 water for irrigation. In some localities away from flow- 

 ing streams irrigation is carried on by the use of water 

 obtained during flood periods by storage in small reservoirs. 

 Such reservoirs, while having small individual capacity, will 

 in the aggregate store large volumes of water that would 

 otherwise go to waste in periods of flood or heavy rain- 

 fall. In this way some good results are obtained in mitigat- 

 ing the effects of overflow and inundation in the larger 

 streams. Of course, no great quantity of water in any one 

 stream is thus held back, but is is expected that eventually 

 a decided benefit in this respect will be effected when the 

 number of reservoirs for impounding storm water has been 

 increased to the maximum limit. 



Development of Irrigation. 



According to the last national census, the total acreage 

 under irrigation in the arid and semi-arid states is given 

 as 13,739,499 acres. This is an increase of 82.5 per cent in 

 the last decade, and 278.3 per cent in the last two decades. 

 The total area of irrigable land in the United States in- 

 cluded in present projects and yet to be irrigated, comprises 

 31,112,110 acres This vast area does not contain the total 

 irrigable land we have ; it is probably about half of what 

 will ultimately be irrigated in the arid region. Prof. 

 Fotrier, an authority on irrigation matters, estimates that 

 the area susceptible of successful irrigation in this coun- 

 try, about 50,000,000 acres of land in the arid region, this 

 area being all that the visible water supply in the territory 

 designated will cover to advantage. When the ultimate de- 

 velopment in irrigation in the West is reached, say in about 

 20 years, the irrigated section will support a population 

 several times greater than at present, and land values will 

 be proportionately higher. 



The extension of irrigation will result in a better con- 

 servation of our water supply, also in a more economical 

 and effective use of irrigation water than is now practiced. 

 As land values increase, improved methods of irrigation will 

 be adopted and water will be made to perform a much 

 greater duty than at present. 



Regulation of Stream Flow. 



With the development of irrigation, involving as it does 



* Address delivered at the Second National Drainage Congress, New 

 Orleans, La.. April 10-13, 1913. 



the conservation of flood waters, we may expect one 

 beneficial result in a greater degree of continuity of flow in 

 our streams. In the navigable rivers a reasonable regula- 

 tion of flow is a consummation that is accomplished, would 

 ir.ean much to navigation. Nature provides through the 

 snow and rainfall a supply of water to the drainage area 

 of a stream system, that with proper conservation, could 

 be distributed along the main channel throughout the season 

 to great advantage. 



In diverting water from a stream channel for irriga- 

 tion purposes the stream flow is not permanently depleted 

 as would at first appear. While a considerable portion of 

 the water so diverted is consumed by evaporation and by 

 the growth of plants, a large percentage collects on the lower 

 levels of the adjacent land in the form of seepage, and this 

 water eventually finds its way back to the channel. 



We are looking forward to the day when our large 

 rivers shall become as easily and effectively managed as the 

 water in the distribution pipes of a large city. This is the 

 highest conception of water conservation, and when it is 

 accomplished, the problems of flood prevention, navigation, 

 irrigation, water power and municipal water supply will be 

 largely solved. In the course of time we may reasonably 

 hope that by the extension of irrigation, the improvement 

 of methods of using irrigation water, and the conservation 

 of flood waters, the great Missouri River may have its 

 flood height reduced and its high water period materially 

 shortened. 



Eventually, from the same source, we may expect to see 

 the low water stage improved by the return of seepage 

 water to the river from tributary streams and reservoirs 

 after this water has performed useful work in the way of 

 irrigation. The regulation of stream flow in other than ir- 

 riated sections may be effected by other agencies, as will 

 be seen later on. 



Reclamation by Drainage. 



Vast as is the area that will be ultimately reclaimed 

 by irrigation in the United States, it is not as great as that 

 which requires drainage. While irrigation is considered 

 necessary in only a portion of the area covered by the 

 continental United States, drainage reclamation is required 

 in forty-one states of the Union. From this we can readily 

 see that in the work of reclaiming agricultural lands, and 

 the drainage of swamp and overflowed lands may be con- 

 sidered as being fully as important as irrigation. Both are 

 important factors in the development of our country and 

 both deserve recogntion and attention by all who have the 

 welfare of our country at heart. Irrigation is receiving 

 national assistance, and deservedly so; now let us have 

 equal recognition for drainage. 



Conditions in South Dakota. 



In South Dakota, as in other western states, there are 

 considerable areas of splendid agricultural lands that are 

 either partially or wholly under water and that can be re- 

 claimed only by drainage. The cost of drainage with us is 

 relatively small when compared with the present value of 

 the land. In many instances, however, the cost per acre 

 would be prohibitory were it not the case that the lands 

 have a high intrinsic value. As is generally the case where 

 agricultural lands require drainage, the wet areas comprise 

 some of the best lands we have and we cannot afford to 

 leave them undrained. We now have proposed and under 

 way many important projects for drainage reclamation, and 

 hundreds of miles of ditches will have been constructed 

 when present projects are completed. 



The general supervision of both irrigation and drain- 

 age work in South Dakota is under the State Engineer's 

 department. While the western half of the state is con- 

 cerned largely with irrigation, in the eastern half drainage 

 problems require our attention. Under the provisions of 

 the state drainage code, petitions have been filed in the 

 State Engineer's office calling for the establishment of drain- 

 age over an area comprising about 330,000 acres of land ; 

 and involving the construction of 425 miles of main ditches 

 and about 1,000 miles of laterals; this area is distributed over 

 27 counties in the state east of the Missouri River. 



Some of our drainage problems are complicated and 

 require considerable engineering skill to design and carry 

 nut. One project that was completed about two years ago, 

 drains several thousand acres in the Sioux River valley. 

 This project, which was designed in the State Engineer's 

 office, requires a main canal haying a capacity of about 2,000 

 second feet of water. The discharge is through an outlet 



