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Shortages Based on Districts' Predicted WY 2001 Operations (Dry Year Prediction) Yeriod (kafl Cont. Average IFR Dry IFR Shortage # of Shorta¢e Total Shortage Total Period Davs Per Dav Shortaee Per Dav Shorta¢e '6-1 to 6=30 -A44. , 17.85 0 0 8-1 to 8-31 " 31 0,44 12:30 0 0 9-1 to 9-15 23.80 0.79 11;90 9-16 to 9=30 15 ' 1.19 17.85 0.40 5:95 Total 405.22 151.14 Water Year 2001 Environmental Account Release Priorities Numerous hydrologic and biologic conditions must be considered throughout the year for determining EA releases. The duration and quantity of water to be released will depend on historic and existing conditions, Service target flow recommendations, EA volume, and release priorities identified in this AOP. Based on predicted "dry" conditions for the 2001 water year and projected flows for the central Platte, the Service identified priorities for each seasonal period (Table 1). Winter/Early Spring (December-March): Central Nebraska experienced another mild winter during the 2000 water year with moderate temperatures, little or no river ice formation or plains snow cover, and little precipitation. As a result, no beneficial pulse flows (e.g., ice scour for channel maintenance, sediment supply, sandbaz formation) occurred during the 2000 water year. In the absence of scouring and/or longer duration pulse flows, in-channel vegetation establishment was extensive. Therefore, high priority will be given to using EA water to augment river flows and promote ice movement and scour to facilitate removal of in-channel vegetation if and when conditions are conducive. Ice and snowpack formation throughout winter and spring and late February and early March precipitation will also be monitored for the effects that river flow management could have on wet meadow hydrology. Whooping Crane Migration Season (March 23-May 10): Flow projections indicate that average and/or dry targets may not be met. Flow augmentation during this period will be prioritized if it is determined that low flow conditions are not providing stop-over opportunities in the Central Platte River for migrating whooping cranes. Late Spring (May/June): If conditions during winter/early spring (with or without EA augmentation) have not resulted in beneficial pulse flows which promoted natural river processes (e.g., ice scour, enhancement of riparian wetland systems, sandbar formation), opportunities to augment May/June pulse flows will be prioritized. Improvement of late spring pulse events is the Service's highest flow priority (Bowman 1994; Bowman and Carlson 1994). Existing long-term averages for pulse flows are well below Service targets and current projections suggest that below Water Year 2001 EA AOP 7 January 3, 2001