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<br />Desalinization <br /> <br />Investi gat ions into the constructi on of a 1 arge-sca1 e seawater <br />desalting plant have shown that high construction costs and the energy <br />intensive nature of the desalting process make this alternative <br />infeasible. Geothermal studies undertaken by the Bureau of Reclamation <br />have also concluded that the use of b ri nes for s i ng1 e pu rpose water <br />augmentation cannot be justified economically. <br /> <br />Evaporatian Suppression <br /> <br />The Bureau of Reclamation has conducted research on ways to reduce <br />evaporation loss from reservoirs. Investigations involved the use of a <br />thi n fil m to cover water surfaces. Researchers found that wi nds Clnd <br />wave action break up the film and move it across the reservoir, reducing <br />its effectiveness. It was the general conclusion that evaporation <br />suppression would not be effective for the foreseeable future. <br /> <br />Vegetation Management <br /> <br />The United States Forest Servi ce has conducted studi es of vegeta- <br />tion management on forest watersheds to increase runoff. The most cost- <br />effective management measures for increasing water yield are c1earcutting <br />timberlands and conversion from vegetation types. Studies have shown <br />that the combined effects of weather modification and vegetation modifi- <br />cat i on on the same area increase streamfl ow more than if the two prclC- <br />tices are applied separately. <br /> <br />Weather Modification <br /> <br />The technology of modifying wintertime orographic cloud systems to <br />increase mountain snowpack has been developing over the past 30 years. <br />Both research and operational projects have contributed to a better <br />understanding of weather modification. The accumulated evidence is that <br />seeding under favorable conditions will increase seasonal snowpack which <br />in turn will increase streamflow. <br /> <br />Background <br /> <br />The evidence that the precipitation process can be significantly <br />altered by carefully control1 ed seedi ng is primarily based on stati sti- <br />cal indications which do not yet have all the necessary physical support <br />to exp1 ai n and veri fy cause and effect re1 ati onshi ps. Where preci pita- <br />tion increases have been suggested, confirmatory experiments are <br />requi red before -any of the technol ogi es can be consi dered sci entifi cally <br />proven. However, despite uncertainties in the evidence for cloud <br />seeding, it is generally supported that seasonal increases in precipita- <br />tion on the order of 10 to 15 percent can be produced in cold orographic <br />cloud systems under favorable conditions with existing technology. <br /> <br />,'Ji...; i <br />