What is Wetland Mitigation?
Wetlands have watershed functions such as, flood retention, nutrient transformation, water treatment and wildlife habitat, and society places values on these functions and therefore a functional assessment is generally conducted to identify these functions and value to determine what needs to be mitigated.
Simply, wetland mitigation replaces wetlands lost due to construction, grading or other activities. Specifically, wetland mitigation is the creation, restoration, or enhancement of wetlands, to compensate for wetlands that were or will be lost due to regulated and permitted activities or non-exempt agricultural activities, that under 404(b) (1) alternatives analysis were found to be the least environmentally damaging practical alternative. Most individual state definitions of wetlands correspond to the Federal definition of compensatory mitigation. Wetland creation projects establish wetlands on upland sites or restore and enhance existing degraded wetlands. These projects usually involve lowering the elevations of uplands by grading the soil for the purpose of increasing the frequency of soil saturation, flooding, and ponding. Wetland restoration projects may reestablish wetlands within the affected watershed on sites where they were formerly located. For example, the removal of drainage structures from agricultural fields can result in wetland restoration if natural ponding and hydrology induce wetland vegetative conditions. Wetland enhancement projects provide additional protection to, or improve the functions of existing wetlands. Planting wetlands that are farmed or dominated by grasses are the most common type of enhancement projects, although do little to replace watershed functions and values. Stream restoration projects, such as stabilizing the banks or restoring the natural meander pattern to a channelized stream, are examples of projects that can enhance existing wetlands. Enhancement projects generally do not increase the acreage of wetlands, they rather improve the natural functions of the resources.
Mitigation is required to compensate for authorized activities which will cause unavoidable losses of wetlands and the Corps of Engineers and EPA 404(b) (1) alternatives analysis.
TYPES OF ACTIVITIES THAT REQUIRE MITIGATION: 1) Removal, excavation, or dredging of soil, sand, gravel, minerals, organic matter, or materials of any kind; 2) Changing existing drainage characteristics, sedimentation patterns, flow patterns, or flood retention characteristics; 3) Disturbance of the water level or water table by drainage, impoundment, or other means; 4) Dumping, discharging of material, or filling with material, including the driving of piles and placing of obstructions; 5) Grading or removal of plant life that would alter the character of a wetland; 6) Agricultural activities in undisturbed wetlands and sometimes in formed wetlands under 404(f).