PRRIP Draft Environmental Impact Statement Summary

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Platte River Draft Environmental Impact Statement Summary of Impacts of Each Alternative Compared to the Present Condition (Impacts are quantified on an annual basis, unless otherwise noted) Resources, Lower by Significant Indicators, and Governance Geographic Areas Committee, 14 percent Scenario 1 Central Platte Basin Nearly 60 percent About 50 percent Lowe Lake McConaughy storage 14 pei Number of spills and amount About 55 pert( of water spilled.5 Total flows Inc Irrigation delivery shortages; island leveling of number of years for the 2 mor Western Canal Improvement toward 142,000 target flows at Grand Island River H,. Mean annual flow at Increase Overton, Nebraska 1.5 -year peak flood at Increase Overton, Nebraska 24.7 percent Channel restoration No island levelinj At 13 years, sand augmented 0 by land plan (tons) At 61 years, sediment eroded Decrease from channel bed at river 1 percent mile (RM) 234 At 61 years, median grain size Increase for channel bed39 18 percent Alternatives Governance Water Wet Water Committee, Leasing Meadow Emphasis Scenario 2 r by Lower by Lower by Lower by ent 11 percent 14 percent 11 pe r Increase Nearly 60 percent About 50 percent About 45 percent nt fewer spills fewer spills fewer spills fewer spills rease average annual flows, especially in spring and summer years I no change acre -feet 1 148,000 acre -feet 1 118,000 acre -feet 1 185,000 acre -feet draulics and Sediment Transport 3,687,000 tons I 3,580,000 tons Decrease Decrease Decrease Decrease 25 percent 30 percent 33 percent 1 percent Decrease I Decrease 11 percent I no change 1 percent 5Spills include spillway flows and releases to prevent violating the FERC limits on maximum reservoir elevation. 6Out of the 48 -year period of record used for the hydrologic analysis. 'Cumulative sand augmented is a measure of the sand input to the channel through mechanical island leveling activities. 'Assuming that no channel restoration or sand augmentation occurs after the 13 -year First Increment of the Program. Increase Increase Increase ;.7 percent 7.7 percent 1.8 percent 5.8 percent Increase Increase Increase Increase 70.7 percent 75.3 percent 69.6 percent 76.2 percent Clearing and island leveling of Clearing and island leveling of 417 acres at six locations 482 acres at two locations 3,687,000 tons I 3,580,000 tons Decrease Decrease Decrease Decrease 25 percent 30 percent 33 percent 1 percent Decrease I Decrease 11 percent I no change 1 percent 5Spills include spillway flows and releases to prevent violating the FERC limits on maximum reservoir elevation. 6Out of the 48 -year period of record used for the hydrologic analysis. 'Cumulative sand augmented is a measure of the sand input to the channel through mechanical island leveling activities. 'Assuming that no channel restoration or sand augmentation occurs after the 13 -year First Increment of the Program.