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Reservoir Storage Reservoir storage remains above average in all of the major river basins, The highest storage volumes, as a percent of average, are in the Arkansas Basin, where storage is 261 % of average, The Rio Grande Basin is also reporting well above average storage at 160% of average, Statewide storage remains well above average as well at 140% of average, This volume exceeds the average by slightly more than 1.2 mi lIion acre-feet of water. While all basins are reporting above average storage, all basins are also reporting volumes near or above last year's storage on this date, Again. the Arkansas Basin is reporting the greatest increase over last year, at 121 % of last year, Statewide storage is 11 % above last year's, Much of this additional water was stored during last summer's wet monsoon season and will be increasingly valuable as we enter a potentially very dry summer in 2000, Streamflow While the additional snow pack has helped ease concerns about summer water supplies, they have certainly not eliminated it. Nearly the entire state can continue to expect below average streamflow volumes, Conditions worsen across the southwestern portion of the state where well below average runoff is forecast. Of greatest concern, are those streams in the Animas, San Juan, and Rio Grande basins, where forecasted spring and summer runoff ranges from only 30% to 50% of average, Along some of the smaller streams and tributaries in these basins, forecasted runoff is the lowest since the drought years of 1977 and 1981. At this time in the winter accumulation season, water users in these basins should make preparations for a dry runoff season, with low peak flows that rapidly recede after the meager snowpack melts, SURFACE WATER SUPPLY INDEX FEBRUARY 1, 2000 Abundant Supply Near Normal Moder.te Drought Severe Drought Extreme Drought The Surface Water Supply Index (SWSI) is a weighted value derived for each major basin which generally expresses the potential availability of the forthcoming season's water supply. The components used in computing the index are reservoir storage, snowpack water equivalent, and precipitation. The SWSI number for each basin ranges from a -4.0 (prospective water supplies extremely poor) to a +4.0 (prospective water supplies plentiful). The SWSI number is only a general indicator of surface water supply condition. Further data analysis may be required in specific situations to more fully understand the impacts of abnormally dry or wet conditions suggested by the SWSI. Development of the SWSI has been a cooperative effort between the Colorado State Engineer's Office and the Natural Resources Conservation Service.