WATERWAY AND LOCATION: The project would affect waters of the United States (WOTUS) associated with an approximately 58-acre parcel adjacent to the existing Nahant Marsh Complex, including wetlands. The proposed site is located within Section 5, Township 77 North, Range 03 East, Scott County, Iowa at Latitude 41.496501 and Longitude -90.633716.
EXISTING CONDITIONS: The site consists of undeveloped areas of emergent, scrub-shrub, and forested wetlands as well as subsurface drained uplands used for row-crop agriculture. Land surrounding the proposed bank area is currently part of the Nahant Wetland Mitigation Bank (Phase I – Ruhl Property), Nahant Stream Mitigation Bank (Phase II), and the broader Nahant Marsh Complex.
PROJECT PURPOSE/BANK OBJECTIVES: The fundamental objective of compensatory mitigation is to offset environmental losses resulting from unavoidable impacts to waters of the United States authorized by Department of Army Permits. Other Objectives include: provide economically efficient and flexible mitigation opportunities when wetland mitigation is required, support the national goal of no net-loss of wetlands, contribute to the long-term health of Iowa’s waterways, provide additional flood storage capacity, and offset small aquatic impacts at an ecologically significant scale that improves landscape connectivity, supports regional biodiversity, an delivers long-term ecological functions that align with watershed-scale conservation priorities. The sponsor also plans to expand the existing Nahant Marsh complex by restoring and enhancing approximately 57.62 acres of adjacent degraded farmland to native emergent and forested wetland, thereby increasing the overall size, habitat diversity, and ecological functions of the marsh, including improved flood storage, water quality, and wildlife habitat connectivity.
PROJECT DESCRIPTION/BANK ESTABLISHMENT: The purpose of the Bank is to provide mitigation credits to satisfy compensatory mitigation requirements for adverse impacts to wetlands and Waters of the United States (WOTUS) within the Mississippi Service Area. The sponsor proposes to complete activities on 57.62 acres of property owned by the Nahant Marsh Education Center that would result in the establishment of wetland mitigation credits.
The goal of the bank is to perform emergent wetland restoration and enhancement as well as forested wetland enhancement with buffer areas on 57.62 acres to generate an estimated 34.63 wetland credits. By restoring degraded farmland and enhancing existing wetlands, the bank will expand wetland area and function within a priority landscape, reduce habitat fragmentation, filter nutrient and pollutant runoff, and improve flood attenuation through increased floodplain connectivity. Because the Nahant marsh is hydrologically connected to the Mississippi River via surface water, anticipated water quality improvements are expected to extend to the river.
The bank sponsor would use restoration and enhancement methods including shallow excavation, subsurface tile removal, shallow embankment construction, installation of a water control structure, reduction of invasive species, installation of native seed mixtures, and management of tree species diversity and densities through timber harvest and plantings. All restored areas, including buffers will be seeded with appropriate native seed mixes.
SERVICE AREA: The proposed bank service area will be the Mississippi Service Area in Iowa.
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