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Show gineering and land phases must be represented. Results from an experiment station conceivably could effect great savings in planned expenditures. 2. Conflicts Between Navigation and Other Uses of Water The Problem Extent of conflict between navigation and other water uses, and possibilities of resolving such conflicts. The Situation The main stem of the Missouri River is legally considered navigable from the mouth to Fort Ben- ton, Mont. This was the portion of the river actually navigated by commercial boats in the past. The reach from Sioux City to the mouth, a distance of 760 miles, is currently under authorized improve- ment for navigation. The project provides for an open channel 9 feet deep and 300 feet wide. A proposal is under consideration to extend the project upstream from Sioux City to Yankton, S. Dak. In addition to providing a navigable channel, the project would prevent loss of some valley lands, create new land, and eliminate the threat of bank erosion which has deterred use of the land and depressed its value. The navigational works consist of permeable pile dikes to shape and contract the waterway, bank revetments, and other improvements. In its nat- ural state, the wide and shallow river was con- tinually cutting its banks. About 10,000 acres of high land were destroyed by erosion each year. A similar amount of sand-bar land was formed. Thus the total area of land, though not its quality, remained fairly constant. Old maps and records indicate that an area of over 600,000 acres near the river was subject to periodic erosion and gradual rebuilding. The bank- stabilization works are to guide the river into a single channel which scours deeper than under natural conditions, and prevents bank erosion and land loss. In addition, sedimentation is induced behind the structures, which will build usable land. Approximately 190,000 acres of this accretion land will be reclaimed from what would otherwise have been channel area. Upstream and downstream interests have been in controversy from time to time because of geo- graphic, climatic, economic, and political diversities in the basin, coupled with periodic deficiencies of natural (unregulated) wate*- supply for present and planned water uses in one or another part of the basin. These deficiencies »iay extend for over a decade. Apparent conflicts between the most important of these uses have included -especially that between water use upstream for irrig-ation and maintenance of adequate supplies of navigation water down- stream. This controversy became very serious in the early 1940's when new plans proposed doubling the amount of irrigation in. the upper basin, and converting the Missouri Ri^ver navigation project between Sioux City and the mouth from a 6-foot to a 9-foot channel. Intensity of the controversy was increased by the fact tr*at stream flow records for the Missouri River then publicly available com- menced about 1930, covering a decade of very low flows. This major basin-wide controversy over use of water of the Missouri River lias subsided somewhat as a result of independent water supply and res- ervoir capability studies by engineers from all the basin States, which concluded that, while no definite estimates of requirements for the several purposes could be made at the time of study, the authorized plans permitted adjustment to more accurate deter- minations later. Other factors affecting the con- troversy have been (a) authorization of the large main stem reservoirs (now under construction) with about 74 million acre-feet of multiple-purpose stor- age capacity to carry water over from wet years to meet low-flow deficiencies, supplemented by tribu- tary reservoirs with large irrigation storage capacity, and (b) congressional recognition of the impor- tance of water to the semiarid western regions through the O'Mahoney-Millikin Amendment in- cluded in the 1944 Flood Control Act and the 1945 River and Harbor Act.2 This amendment assigns priorities in water use in the basin. It specifies that use for navigation, in projects authorized by the act, of waters arising in States lying wholly or partly west of the ninety- eighth meridian shall not conflict with any beneficial consumptive use in those States of such waters for domestic, municipal, stock water, irrigation, mining, or industrial purposes. The constitutionality of the amendment has not been tested. The compatibility of navigation with other water uses must further be considered in the light of: (a) reservoir operation for multiple purposes as affect- 2 Act of December 22, 1944, § 1, 58 Stat. 887; Act of March 2, 1945, § 1, 59 Stat. 10. 198 |
