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I I I I I I I I I I I I I I I I I I I 1998 OPERATIONS SUMMARY AND RESERVOIR STATUS Water year 1998 observed near normal hydrologic conditions in the basin with near normal precipitation translating into average snowpack. At the beginning of the runoff season the basin wide snowpack was near normal. Great media and public attention focused on the strong EI Nino Southern Oscillation (ENSO) anomaly present in the equatorial region of the Pacific Ocean and the potential effect this might have on the Colorado River Basin. Reservoir drawdowns in the winter of 1997-98 were slightly greater than normal in a conservative attempt to prepare for potential high spring runoff. However, water year 1998 did not have the spring precipitation, cold temperatures, and extreme runoff that characterized water year 1983 (another strong ENSO year) and the spring runoff did not cause significant operational problems. Unregulated inflow into Lake Powell was 16,850 MCM (13.660 MAF) in water year 1998, approximately 116 percent of average. Releases in response to this inflow resulted in a drop of approximately 491 MCM (0.398 MAF) of storage in Lake Powell. Approximately 418 MCM (0.339 MAF) of storage was lost in upstream reservoirs, approximately 1,723 MCM (1.397 MAF) was gained in Lower Basin reservoirs, and the total Colorado storage system gained approximately 814 MCM (0.660 MAF) during water year 1998. It is estimated that with average inflow during 1999, the system will remain relatively full. During 1998, all deliveries of water to meet obligations pursuant to "The Law of the River" were maintained. Tables 1 (a) and 1 (b) list the October I, 1998 reservoir vacant space, live storage, water elevation, percent of capacity, change in storage, and change in water elevation during water year 1998. 3