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Title: Supplemental Environmental Assessment : West Bank & Vicinity Hurricane Protection Project, Implementation of Previously Authorized Mitigation Plans, St. Charles, Louisiana : SEA #498A
Authors: United States. Army. Corps of Engineers. Mississippi Valley Division
Keywords: New Orleans (La.)
Environmental management
Flood control
Publisher: United States. Army. Corps of Engineers. New Orleans District.
Abstract: The proposed action would modify the St. Charles Mitigation plan discussed in accordance with Supplemental Environmental Assessment #498 (SEA #498). In SEA #498 the proposed action for mitigation at the St. Charles (STC) site was: “…the STC site would include preserving through acquisition alone approximately 1,211 acres of existing cypress Swamp/BLH [bottomland hardwood], while an additional 90.9 acres would be preserved through active management activities after acquisition. Management construction activities would include selective tree removal and tree girdling and/or injection to enhance snag numbers, as well as planting with desirable species in selected areas. Additionally approximately 12.8 acres of BLH dry species would be planted in areas previously cleared for roads as part of the Willowridge subdivision, Phase 6... A total of 1,321 acres would be acquired at the STC site.” (USACE 2012) The STC project was approved and authorized with a Finding of No Significant Impact (FONSI) on July 13, 2012. SEA #498 is herein incorporated by reference and can be found in Appendix F. The new proposed action would modify the previously developed and approved mitigation plan to enhance, and re-establish swamp and BLH habitat due to changes at the STC site. The proposed action would achieve the same amount of mitigation but requires additional actions due to changes in conditions at the mitigation site. Since the release of SEA #498 (2012) there has been obvious tree mortality. This mortality seems to have been induced by increased inundation over time due to a new pumping station and the existing berm impeding water exchange. Therefore, modifications to the plan are required for the STC mitigation site to achieve mitigation. The goal of the proposed action is to improve hydrology, and re-establish approximately 74 acres of BLH and swamp tree species native to southern Louisiana. Actions to restore the hydrology of the mitigation site and maintain the prescribed habitat for mitigation includes, constructing twelve 100 foot cuts in the existing berm at 500 feet intervals to improve the exchange of water. Additionally, to address the current loss of trees, approximately 74 acres of BLH and swamp species would be planted in areas described in section 2.3 and in Figure 3 of Appendix A. Acquisition, preservation and management would remain as described in SEA #498. The purpose of the proposed action is to restore the exchange of water within the wetlands by constructing berm cuts and to plant approximately 74 acres of BLH and swamp species to re-establish BLH and swamp species lost to mortality. These actions would satisfy the mitigation requirements related to the West Bank and Vicinity Project as authorized prior to Hurricane Katrina. Mitigation requirements, plans, and designs were originally defined in the three FR/FEIS for the West Bank and Vicinity, New Orleans, Louisiana Hurricane Protection Project and in SEA #498 (2012). Changes in the environment since the release of SEA #498 have necessitated a reassessment of the mitigation plan at the St. Charles site. This SEA supplements SEA #498 (USACE 2012).
Description: Supplemental Environmental Assessment and Finding of No Significant Impact
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Environmental Documents

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