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. Horseshoe Bend Bottomland -Horseshoe Bend provides another opportunity to experiment with a longer levee removal area. A cut extending 1000' along the lowertwo-thirds of the bottomland has been proposed (see sheet B-2). Approximately 70'-100' of the width of levee will need to be removed to connect the river to the bottomland. The controlling flooding elevation of 4698.9 will be set 50' back from the bank cut of 4697. The center of the Horseshoe bottomland is a mudflat area with no significant wetland or any type of vegetation. It has been proposed (Alternative 1) to place the majority of the spoils pile in this center part of the pond, as it would be desirable to raise the elevation of the pond. The fill material provided by Altemative 1 would only raise the lowest elevation of the pond by one foot. Yet, Alternative 2 of placing the large volume of spoils material above of the high water mark would require approximately 52,500 square feet of land and great expense. Assuming Alternative 1, some of the spoils will still need to be placed above the high water mark to bury the cut vegetation. With either spoils placement alternative, the pile should be revegetated and aesthetic concerns addressed. The estimated construction cost of restoration activities at Horseshoe Bend is $41,000.00 Stirrup Bottomland - A smaller channel cut has been proposed for the Stirrup Bottomland site. An existing swale which is filled with debris from historic floods, was located in the field during the topographic mapping of the site. It has been proposed to connect this swale to a channel cut to the river designed to flood at 13,000 cfs. The proposed 20' wide channel extends 480 lineal feet from the river to where the swale matches an existing grade which provides a hydraulic connection to the bottomland (see sheet B-3). The mouth of the channel will be 40' wide and will neck back to 20' at the flooding elevation location 100' back from the river. Existing cottonwood logs will be embedded into the channel and set to the 4686.5 flooding elevation. The spoils can be placed up along the side of the channel cut which would be out of the high water mark, The approximate cost of restoration activities at the Stirrup Site was $10,000.00 This Stirrup design provides a narrower but longer hydraulic connection, utilizes a historic connection, and provides a greater ease of construction. In addition, high voltage power lines exist along the site which actually cross over the lower extent of the site. As a safety and liability concern, potential scouring of areas adjacent to the power poles wi(I be avoided by this design as opposed to a larger scale levee removal upstream. Baeser Bend Bottomland - A narrow breach has been proposed at the Baeser Bend Bottomland. Several large cottonwoods, and a heavily vegetated levee presented several design constraints at this location. The width of the Baeser Bend cut would be 20' wide and extend back approximately 200' to connect the river to the approximate center of the bottomland (see sheet B-4). Spoils would be placed along the adjacent levee which is well above the high water mark. The equipment access to this site is more difficult due to the heavy vegetation. The thick vegetation along this levee may help to reduce large scale scour along the levee. The flooding elevation will be set back 50' from the river and armored with available material embedded into the channel. The bank cut will be 2.5' lower than the flooding elevation. The success of the bottomland floodplain habitat restoration activities will be assessed before modifications to Baeser Bend are enacted. Construction activities are not planned any earlier than the fall of 1997, and are subject to the success of the other restoration activities. The estimated cost of construction activities at Baeser Bend is $14, 000.00. Above Brennan Bottomland -The Above Brennan bottomland currently functions with flooding initiating at approximately 12,900 cfs. No floodplain restoration activities are planned for this bottomland prior to the 1997 runoff season. This bottomland will act as a control for research purposes at least through the 1997 runoff season. Potential flooding enhancement at a lower drain location has been proposed for the future. At the lower extent of the bottomland a drainage outlet exists (see sheet B-5). It has been proposed to lower the elevation and widen this drain to function at 13,000 cfs. The inundation elevation for this drain (4675), will be set back 50' from the bank cut which is 2' lower. Depending on the 1997 studies, this design may be modified to enhance habitat. The estimated cost of construction activities to restore Above Brennan • is $14,000.00. 56