| OCR Text |
Show The Bureau of Reclamation published a repo River Water Quality Improvement Program. "•*• " Prior to their authorization, it was known that the Colorado River Storage and participating Projects, Navajo Indian Irrigation Project, San Juan- Chama Project, and the Fryingpan- Arkansas Project would cause significant increases in salinity levels. This was expected to arise primarily from the increased consumptive use of water and transport of high quality water out of the basin. Recognizing the concern of the Colorado River water users, Congress stipulated that studies be made of the water quality in the basin and that control plans be developed. The stipulation was expressed in the authorizing legislation for the projects." 1" A salinity control study for the entire Colorado River Basin is in progress. Basically this study is designed to investigate ways to reduce the salt load in the lower portion of the river to offset the affects of the upstream depletion associated with authorized developments and to determine if such salinity reduction measures are economically feasible. A basic network of water quality stations has been established at principal points throughout the entire basin to facilitate the study and to help identify high saline sources that might be intercepted, and removed from the river system. The Bonneville Unit impact on water quality of the Colorado River would be to increase the average concentration of dissolved solids below Hoover Dam about 10 mg/ l to Ik rag/ l as estimated by the Bureau of Reclamation and the Environmental Protection Agency, respectively. Historically, the average annual salinity concentration of the Colorado River below Hoover Dam has varied from a low of 6l0 mg/ l in 19^ 9 to a high of 839 mg/ l in 1956. Based upon present modified conditions, the average salinity below Hoover Dam is estimated to be 7*+ 5 mg/ l. The anticipated salinity increase due to future developments will range from 171 mg/ l to 226 mg/ l which would increase the average concentration from 7*+ 5 mg/ l to the 9l6- to 971- mg/ l range. The amount of increase attributable to the Bonneville Unit would be 10 to lU mg/ l or about k percent of the total estimated increase. Thus, the Bonneville Unit, separately, would have only a minor effect on the salinity increase. However, its contribution to a serious and cumulative problem is recognized. Recently the Environmental Protection Agency estimated an annual cost of $ 1+ 1,^ 00 per mg/ l increase to water users below Hoover Dam for salinity increases from the Bonneville Unit. Using this estimated • cost, the annual economic impact attributable to the Bonneville Unit would range from $ 1+ 1^, 000 to $ 580,000 for salinity increases of 10 mg/ l and Ik mg/ l, respectively. The salinity problem of the Colorado River as it relates to the Bonneville Unit is discussed in Sections B through F, of the final statement, under the heading of Water Quality. in 1972 entitled " Colorado This report states, 658 |
