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Colorado Drought Hazard . Bureau of Land Management . Bureau of Reclamation . Private Interests Task force members utilize their various informa- tional resources to develop water availability statisti- cal data and trends. Data collection, evaluation and reporting activities focus on major problem areas across the state. When activated, the Task Force col- lects water availability data, evaluates these data, and makes assessments regarding changes in avail- ability and trend projections. Key areas of water shortage are identified and these assessments and projections are reported to the Task Force Director. Surface Water Supply In.dex (SWSI) Colorado's droughts of 1976-77 and 1980-81 prompted the development of a Surface Water Supply Index. SWSI and the Palmer Index are currently the two in- dices recognized in the Colorado Drought Response Plan for officially monitoring drought conditions, and then activating appropriate impact task forces to deal with drought effects. (The Palmer Index is described in detail in the Ahnnt n......ldd pamphlet). Develop- ment of the SWSI is a cooperative effort between the Colorado State Engineer's Office and the Soil Conser- vation Service. SWSI is a weighted value derived for each major basin that generally expresses the poten- tial availability of the forthcoming season's water sup- ply. The components used in computing the index are reservoir storage, snowpack water equivalent, and precipitation. The SWSI number for each basin ranges from a -4.00 (prospective water supplies extremely poor) to a +4.00 (prospective water supplies plentiful). The SWSI number is only a general indicator of sur- face water supply conditions. Further data analysis may be required in specific situations to more fully understand the impacts of abnormally dry or wet co.n- ditions suggested by the SWSL Emphasis is placed on those areas dependent on surface water supplies origi- nating as snowmelt in the mountains and classified as mountain water dependent. Nevertheless, the SWSI is a year-round assessment tool that is adapted to Colo- rado's overall environment. Water Use in Colorado During 1985, an estimated 20,800 million gallons of water per day was used in Colorado (based on the re- port RlIiIti"lllAtAd llllA of Water in ("A)lnl"'Adn lARA. n.R ("......1,.,;.....1 SU1'Va)' Rilport AA-41011. Of this quantity, 89 percent came from surface water sources and 11 percent came from groundwater sources. COLORADO WATER USE OTHER 3% POWER 35% Of all water used, 60 percent was used for irrigation, 35 percent for power generation, and the remaining 5 percent for commercial, domestic, industrial, livestock, mining, and other uses. Public supply systems pro- vided only 4 percent of all water used in Colorado, but provided 80 percent of all commercial, domestic, and industrial water used. Ninety-three percent of the people in Colorado obtained their domestic water from public water sources. For the entire state, an esti- mated 4,840 million gallons per day of water was con- sumptively used during 1985. Return flows were about 16,000 million gallons per day. Water-use information is needed for two reasons: - First, it is needed by people seeking to understand the hydrologic system. In order to construct a water budget for an area, it is necessary to know how human activities affect water entering and leaving an area. Such an understanding is useful to . the citizen as well as to the scientist because water is a necessit]l for daily life. - Second, water-use information is needed by those who wish to plan for an area's future needs. Analy- ses of patterns and trends in water-use data can aid in developing an understanding of the nature of 16