WSP12061 - Laserfiche WebLink

Home Browse Search

111-4 I I I I I I I I I I I I I I I I I I I Domestic Non-Central The U,S. Department of Agriculture computed the estimated water use from non-central systems for domestic use. Less than 20 percent of the people in the Missouri River Basin use self-supplied water and the effects on total water supplies of this use are insignificant. Manufacturing The Bureau of Domestic Commerce of the U.S. Department of. Commerce computed current and projected manufacturing water use for the MCC. 1. Manufacturing water demands are related directly to the output of manufacturing products and have no direct relationship to employment or population. 2. Because of the variety and multitude of products, a proxy for production must be substituted. 3. The gross product originating, a constant dollar measure of the output of an industry, may serve as a proxy. This can be derived from OBERS constant dollar earnings with coefficients provided by OBERS. 4. Manufacturing economics dictate that the least-cost method of providing for the water demand (gross water demand) will be selected from the array of water management options ranging from once-through use (by which gross demand and withdrawal are the same), to a completely closed system in which water is continuously recirculated and, in which after the initial provision of water, withdrawals are reduced to zero, 5. Gross water demand, with its relatively fixed relation to 'production or its proxy, is the key parameter for assessment of industrial water demand. The withdrawal demand is an element of the gross demand dependent on the degree to which the water is reused or recycled in the production process. 6. Consumption of water in manufacturing is also related directly to the output of manufactured products, Thus, consumptive use increases with the growth of the manufacturing sector and its output. Consumptive use, which results mainly from evaporation, may be slightly higher in a plant that recycles water than in one that does not, 7. Because it is anticipated that manufacturers will practice water recycling to an increasingly greater extent, withdrawal demands may be expected to decrease in most cases in the near future, even though gross water demands increase. 8. There are limits to the degrees of recycling that can be achieved, which, once reached, result in the rates of change in withdrawals returning to parallel the rates of change in gross demand. These limits are consumptive losses which impose a minimum requirement below which withdrawals cannot fall, and the buildup of dissolved solids in the recycled water. g. The central case information includes the water demands of small water users as well as large, It was assumed that small water users obtain water from public systems and will discharge to public waste treatment facilities, generally not recycling treated effluents in their plant processes, Nationally, the small water users account for only two percent of the total manufacturing demand.