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SEellONTWO EnVironmental Setting I I I ,I I I 1 1 I 1 I 1 occurs in midsummer and early fall, when river discharge is low and it is possible to drive equipment across river channels (Trust] 998). Other clearing methods have included logging; chainsawing, burning, use of dozers and excavators, and herbicides (FWS 1998). River clearing efforts have concentrated on islands within the main channel. However, vegetation along the banks also has been cleared in some areas to achieve a minimum unobstructed channel width of 1,000 feet. Periodic maintenance of cleared river channel is necessary to remove newly established seedlings. High instream flows remove new seedlings, but the frequency with which they occur is too low to maintain cleared areas without periodic mechanical intervention. Therefore, clearing or discing usually is repeated every 2 to 5 years. The Trust has cleared river channel habitat on its own property and on property belonging to The Nature Conservancy, National Audubon Society, and private landowners. Cooperation with private land owners has been accomplished by Third Party Agreements with the Trust and the FWS. Such agreements facilitate the pennitting process with the U.S. Army Corps of Engineers (CO E), since COE permits need to be approved before river work can begin. Nesting habitat for least terns and piping plovers has been created within the Platte River in several areas. The Trust created four sandbar islands in 1990 using an SC Underwater Pump dredger to dredge sand from the river bed and create new sandbar islands (Trust 1998). Four sandbar islands were created at the Trust's Wild Rose, Shoemaker, and Uridil properties, and another was created at Overton in a cooperative agreement with Nebraska Public Power District (NPPD). These sites are maintained by discing. NPPD has created three nesting islands (NPPD 1998). The first was at Elm Creek Island in 1991, and it was created using vegetation clearing, importing of clean sand and gravel, and cutting of a new channel to create an island (FWS 1998). The Overton nesting island was created using a combination of clearing and dredging of sand and gravel from the river channel. These nesting islands are maintained by a combination of methods including pre-emergent herbicides, discing, and mowing. All of the NPPD nesting islands have changed in size and shape since construction, due to erosion and deposition by the Platte River (NPPD 1998). NPPD has also developed and managed three sand pits as nesting habitat (NPPD 1998). Most of the bottomland grassland restoration conducted to date was also done by the Trust. Restoration of grassland and wet meadow has been done to increase the availability of these habitat types, and to convert cropland to wildlife habitat. The Trust has established 1, I 07 acres of grassland and wet meadow habitat along the Platte River, all within 1.5 miles of the Platte River. (Trust 1998; Pfeiffer 1998). Several techniques have been used, including groundwater pumping, dam and dike construction, land contouring, and a variety of reseeding strategies (Currier 1994, 1997). Methods for re-establishing bottomland grasslands and wet meadows are still being evaluated. Two of the largest remaining bottomland grasslands/wet meadows in the Platte River Valley are used as benchmarks for evaluating success: Monnon Island Crane Meadows (a high diversity, very wet site) and the Binfield Site (a lower diversity and drier site). The majority of the remaining cropland owned by the Trust (1,490 acres) is slated for grassland/wet meadow restoration in the future. Seeding strategies have included low diversity (3 to 6 species) Conservation Reserve Program (CRP) type grass plantings on crop fields; clearing, spraying, and burning of riparian forest to IRIS ~ IMt..JwanfI:l1* 2-12 "FOD9nOSOO/n doC 6/21'999(9," AM)/URS"""FS12 Feder.II SIll iIfI:es