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<br />. <br /> <br />. <br /> <br />- 2 - <br /> <br />The structural works include 388 water-spreading and diversion structures at <br />a total cost of $322,000 and 2,800 small detention dams at a total cost of $1,464,000. <br />It is thus apparent that about two-thirds of the cost of installing the program is <br />charged to structural works of engineering rather than agricultural nature. The <br />report claims these works are necessary to afford immediate relief to the people in <br />the area until the vegetal measures included in the program become fulJy effective. ." <br /> <br />The Bureau of Recl8lp.ation is concerned primarily with the impact of the pro- <br />posed United States Department of Agriculture program for the Fountain River Water- <br />shed upon the operation of existing irrigation projects and upon the planning, design, <br />and operation of proposed Reclamation projects in the Arkansas River Basin. The <br />items of principal concern are: <br /> <br />a. Effectiveness of the proposed program upon the reduction of floods. <br /> <br />b. Effectiveness of the proposed program upon reduction in sediment load <br />of Fountain River and its tributaries. <br /> <br />c. Net effects of the proposed program upon stre,am flows, particularly <br />their availability for irrigation and municipal water supply. <br /> <br />d. Determination of whether the proposed program will conflict .vi th the <br />law of the River for the Arkansas River as represented by the Arkansas River <br />Compact approved May 31, 1949 (Public Law 82--81st Congress) and the- pertinent <br />State Laws of Colorado and Kansas. <br /> <br />In evaluating the effectiveness of the proposed program upon the reduction of <br />floods, the report has presented a theoretical hydrologic analysis based on data <br />from infiltrometer tests on areas representing present and improved vegetal cover <br />conditions. No firm data of flood runoff from water studies comparable to the plains <br />area of the F'ountain River watershed are included in the report for both present and <br />improved cover conditions. We question that the theoretical hydrologic analysis <br />based dB infiltrometer data provides a realistic estimate of the reductions in flood <br />flow which would result from the proposed program. The Bureau of Reclamation has <br />made considerable use of infiltrometer tests as a basis for deriving infiltration <br />rates in plains areas. However, we have found such infiltrometer tests to be not <br />app:j.icable directly' as true retention ra. tes. They are useful only as indices of such <br />rates. Our experience has been that such infiltrometer data are on the average about <br />1-1/4 times the actual retention rates experienced during major storms covering <br />major watersheds. The subject report has apparently applied the infiltrometer rates <br />directly without any reduction for retention on a watershed basis. If such a re- <br />ductton were applied, the resultant surface runoff volumes from the design storms <br />would be increased and the percentage spread between runoff from the present and <br />improved conditions would be considerably decreased. Also, it has been our experience <br />that infiltrometer tests as a basis of predicting retention rates for mountain water- <br />sheds bear vcr'J' little similarity to the results obtained by hydrograph analysis <br />of actual flood events. <br /> <br />While the Survey Report indicates that the program of soil and cover improvement <br />will reduce surface runoff flood volumes by from 5 to 12 percent, the major reductions <br />in flood volume and flood peak are claimed to result from the many small detention dams. <br />Thus, the average reduction in flood peak for the entire l"ountain Hiver Watershed <br />