OCR Text |
Show is 500 sec.-ft. or 360,000 acre-ft. annually. Without seepage water this area would have only a flood-water supply and its economic importance would shrink at least one-half or probably from $40,000,000 to $20,000,000. Seepage or return waters have attained such volume on the U. S. Reclamation Service projects that the Federal Government now makes specific claim for such waters on the various projects. On the North Platte Project in Wyoming and Nebraska, the Shoshone Project in Wyoming, and others, the volume and value of such waters is so great that litigation has resulted. Source of Return Flow-In the process of conveying water to land in unlined canals and its application to crop production there are excessive losses. Roughly they may be tabulated as follows: Range Average Conveyance or seepage losses by deep percolation from unlined canals and laterals ........................ 20-50 35* Field losses by deep percolation and surface waste in application ............................................ 10-20 15 Evaporation losses from canal water, saturated ground surfaces and irrigated fields .................. 10-30 20 Plant evaporation or transpiration (actual water consumption) ........................................................ 20-40 30 *Mean of 21 U. S. Reclamation Service projects, 7 years' record, 1912 to 1919, inclusive. From the foregoing table it is evident that the plant consumption of water is, roughly, only from one-fifth to one-third of the water diverted at the river headgate; also it is evident that (excluding lined canals) deep percolation losses in canal, lateral and field, amount to 50 per cent of the water diverted. Probably 50 per cent is a general figure for large areas and varied conditions. Where water is scarce and application is made with good hus- |
Source |
Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : California exhibits. |