plan of flood control and water conservation, separate consideration of which was warranted. The proposed interim report gives separate consideration to such channel training and bank-protection works. Completion of the comprehensive report on the resurvey is awaiting approval of the proposed interim report and availability of information developed in the concurrent hydrologic investigation of the Salinas Basin by the State Division of Water Resources. FEATURES OF PLAN The proposed plan of improvement consists of correction and stabilization of about 93 miles of the Salinas River between its mouth at Monterey Bay and a point about 3 miles south of San Ardo, and of about 1 mile of the Arroyo Seco above its confluence with the river. The improvements are designed to confine floods not in excess of 50,000 cubic feet per second to the stabilized channel. The proposed dimensions of the rectified channel vary from 1,100 by 7 feet in the upper reaches about Soledad to 540 by 15 feet in the lower reaches below Spreckels. The principle elements of the plan of improvement are set forth in paragraph 70 on page 31 of the proposed report as follows: "The plan provides for clearing the channel of willows and other native vegetation; construction of about 80 bank-miles of channel-training works, consisting of jacks anchored by dolphins and cables; the construction of about 60 bank-miles of flexible-type bank-protection works along present or later-established bank lines where required, and along the upper and lower parts of the channeltraining works where needed for protection of the cable-anchor zones; the construction of about 12 bank-miles of a lighter type wire-mesh bank revetment along the convex side of bends and at other places where the banks are not subject to major attacks by the current; the construction of about 10 miles of earth dikes across swales and along low-bank areas to assist in confining the current to the main channel of the river; excavation of about 1.5 miles of pilot channels, about 20 feet wide across points near river miles 20 and 50; and protective planting of willows, baccharis, and other native vegetation on the banks and in the areas behind the channel-training works and bank-protection works." The proposed plan of channel improvements will not entail any alterations to bridges or other existing facilities. Cost of proposed works. The project first cost of the Salinas River channel-improvement works is estimated in the report under review at $1,960,000. The cost therein are based on present conditions for construction work. The amount opposite each feature of work below includes contingencies, overhead, and supervision. (a) Federal first costs: (1) Channel clearing and maintenance during construction__ (3) Flexible type of bank-protection fence_ (4) Wire-mesh revetment (5) Earthwork for dikes and pilot-channel construction__. Total Federal first cost_ (b) Non-Federal first costs: Easements for channel-improvement construction and maintenance (total non-Federal costs). $20, 800 975, 300 645, 300 84,000 97, 400 82, 200 1,905, 000 55, 000 1,960, 000 The total annual charges for the Salinas River channel-improvement works are estimated in the proposed interim report at $95,100, which are divided as follows: (1) Federal annual charges interest and amortization--. (2) Non-Federal annual charges: (a) Interest and amortization. (b) Maintenance__ Total annual charges. $76, 300 2, 600 16, 200 95, 100 The life of the project for purposes of maintenance estimates in the report under review is assumed to be 50 years. The maintenance estimates are based on further assumptions of replacement of 50 percent of the works during that time and complete channel clearing equivalent to once in every 10 years during the life of the project. A break-down of the annual maintenance estimate follows: Subitem (1) Channel clearing. (2) Channel-training works. (3) Flexible type of bank-protection fence_. (4) Wire-mesh bank revetment__ (5) Earthwork for levee and pilot-channel construction_. (6) Protective planting for bank and bay reaches-- Total annual maintenance cost.. ANNUAL BENEFITS Annual cost $1,300 7,700 5, 100 700 800 600 16, 200 The average annual benefits from flood damages prevented, including the existing bank-protection expense saved, are estimated in the report under review as follows: (1) Reduction in average annual damage from inundation_-_. $37, 350 (2) Average annual damage prevented in bank cutting and loss of protection works (3) Average annual damage prevented to railroads_. 38, 850 9,700 (4) Average annual damage prevented to roads and bridges_. 0 22, 600 Total annual damage prevented_--- 108, 500 On a basis of the foregoing estimates, a favorable ratio was found of annual benefits to annual costs of 1.14 to 1.00. PRIOR REPORTS No prior War Department report has been submitted for flood control on the Salinas River drainage basin. The Division of Water Resources, Department of Public Works, State of California, published a report in 1933, entitled, "Report on Salinas Basin Preliminary Investigation." This report refers to and summarizes the unpublished report by Geologist Chester Marliave on the geology of dam sites in the Salinas River stream system. A summary of hydrologic information on the Salinas Basin is set forth in the report. It sets forth a conclusion that the average long-time natural replenishment of the underground basin is probably sufficient for a water demand based on use in 1932, but if the demand from 1928 to 1931 was to recur continuously there would exist a permanent overdraft which must in time be remedied. The peak demand of 1931 on ground water in the Salinas Basin was exceeded in 1939, 1943, 1944, and 1945. Manifestations of overdraft in the ground water in the delta area became serious early in 1944. The field work has been completed on an investigation of the water problems in the Salinas Basin commenced by the State Division of Water Resources in July 1944. A report on the results of the investigation is in the course of preparation. Six early reports on conditions in Salinas Valley have also been reviewed. These are: (1) Charles D. Marx: Report on Irrigation Problems in the Salinas Valley. This report covers problems incident to gravity diversion systems in Salinas Valley in 1901. Pumping from ground waters was unimportant at that time. There is little helpful information in this report on present problems. (2) Homer Hamlin (1904): Water Resources of the Salinas Valley-Water Supply Paper 89. Good information on a few possible reservoir sites are set forth. These were considered from the standpoint of water conservation. (3) W. O. Clark (1916): Measurements of Depth to Water in Wells in the Salinas Valley-unpublished. These records were obtained from the United States Bureau of Soils and included in the supplement of the Division of Water Resources' report in 1933. (4) M. H. Lapham and W. H. Heilman (1901): Soil Survey of the Lower Salinas Valley. This early soil survey covered the area from King City to Monterey Bay in Salinas Valley. 87116-46-33 (5) E. J. Carpenter, A. E. Kocher, and F. O. Youngs (1924); Soil Survey of the King City Area. This is a resurvey of the area from Soledad to King City and new survey from King City to Wunpost. (6) E. J. Carpenter and Stanley W. Crosby (1925); Soil Survey of the Salinas Area. This is a resurvey of the area from Soledad to Monterey Bay. CALIFORNIA STATE HIGHWAYS The State division of highways reports that major State highways run along the course of the Salinas River and cross it at a number of points. This State division has been assured by the district engineer that arrangements will be made for inspection by its representatives of the detailed plans during their preparation. The division of highways expects to be notified and to cooperate as soon as details of the proposed works become available. FISH LIFE The State department of natural resources recommends that, if the proposed interim report is adopted by Congress and appropriation made therefor, construction be so conducted that fisheries resources may not be injuriously affected by the interruption of the surface flow in the Salinas River. CONCLUSIONS The State division of water resources has conducted a hydrologic investigation of water problems in the Salinas Basin, involving water conservation, concurrently with the survey by the district engineer for flood control and related matters. The hydrologic investigation has revealed need for water conservation in the basin in addition to necessity for solution of the general flood-control problem. The proposed interim report covers a plan of initial improvement, which would be an integral part of any comprehensive basin plan for flood control and water conservation. Formulation of plans for a comprehensive multipurpose project are pending approval of the initial improvement set forth in the interim report under review. The review and study of the proposed interim report included consideration of the following matters: 1. Necessity for the proposed works. 2. Effect of proposed improvements on an ultimate comprehensive basin plan. 3. Effectiveness and feasibility of the proposed works. 4. Economic justification of the proposed project. Based upon the review and study of the proposed interim report, and the reports of the Board of Engineers for Rivers and Harbors, division engineer and district engineer, and an analysis of pertinent reports, data and information in the files of the State Division of Water Resources, and an examination of trial installations of proposed type of works in the affected area, is concluded as follows: 1. The necessity for the proposed channel training and bank protection works is of an urgent nature. Local interest therein is unquestioned. 2. The proposed plan of improvement consisting of correction and stabilization of the lower 93 miles of the Salinas River and the lower 1 mile of its tributary Arroyo Seco will not entail any alterations to bridges or other existing facilities. 3. Substantially the entire economy in the Salinas Basin is based on an adequate supply of ground water. An area of 125,300 acres was irrigated from ground water in the basin in 1944 between Monterey Bay and river mile 93. All water requirements in the basin for domestic, municipal and industrial purposes are supplied from ground water. The principal source of replenishment of the ground water is percolation from stream flow in the channels of the Salinas River and the Arroyo Seco. An analysis of the proposed work in relation to contribution to ground water indicates that consummation of the plan of improvement would induce a more favorable rate of river percolation between river miles 46 and 93, and the remainder of the area probably would not be affected. 4. Results of recent investigation by the State Division of Water Resources of problems in the Salinas Basin relating to conservation indicate present combined demand for water on 50,000 acres in the pressure area between Monterey Bay and river mile 34 exceeds the rate of safe yield of the principal aquifer that supplies about 95 percent of the draft. This has resulted in marine intrusion in the waterbearing formation near the bay shore. The proposed plan of improvement would probably result in a deepening of the channel of the Salinas River about 2 feet in the vicinity of river mile 34, which will tend to cause a corresponding drop in elevation of the water table at the fountain head of the pressure area. This may decrease the rate of safe yield of the principal aquifer in the pressure area, on which an overdraft presently exists, between 1 and 2 percent. This slight disadvantage will have no material effect on the solution of the existing water conservation problem, and will largely be offset by anticipated additional percolation benefits between river miles 46 and 93 as above set forth. 5. Structural features and effectiveness of design of the type of channel training works proposed are not clearly beyond the experimental stage. While estimated performance cannot be guaranteed, the favorable ratio found of annual benefits to carrying charges, and beneficial results of trial installations justify expenditure of public funds for the channel improvements as proposed to perfect this type of works by elimination of defects, if any, revealed in a complete and full demonstration. The benefits of perfecting this type of channel improvements would be available for other areas throughout the country where similar works are required. 6. The local interests should not be required to assume, after the period of construction, more than ordinary maintenance charges in the order of the annual amount estimated as $16,200 in the proposed interim report, until such time as the works are perfected and the adequacy thereof is completely and fully demonstrated. Any unusual costs for maintenance after the 5-year period of construction that may be chargeable to experimental work, which would result in benefits to other areas, should be borne by the Federal Government until such time as the designs are declared by the Secretary of War to be perfected. 7. There are water-conservation problems in the Salinas Basin, in addition to the general flood control problem, that require early solution in order to maintain the present economy of the area. Approval of the proposed channel improvement plan appears to be prerequisite to the formulation of plans for a comprehensive multipurpose project for the basin. RECOMMENDATION In view of the foregoing, it is recommended that the project as set forth be approved and be authorized by Congress for immediate construction and at the appropriate time that full consideration be given the matter of classification of costs for maintenance incurred after the 5-year period of construction, properly chargeable to experimental work, as a Federal obligation. The CHAIRMAN. The committee stands adjourned. |