05/08/17 - Laserfiche WebLink

Home

1.4.2 Wetland Buffer Standards Wetland buffer standards were developed with the focus on the buffer widths necessary for protecting water quality and for providing wildlife habitat. Suggested wetland buffer standards in Table 1.1 were developed based on a review of the scientific literature. The literature shows that the effectiveness of wetland buffers in removing sediments and nutrients from surface runoff varies widely due to many factors which include but are not limited to: slope, vegetative cover density, vegetation types, and width. Typically, buffers are established for their water quality improvement potential. High quality wildlife habitat requires significantly wider buffers and higher vegetative diversity/integrity. Results from numerous studies on the effectiveness of buffers for improving water quality were 9 compiled in a report prepared for the Minnehaha Creek Watershed District. This data suggests that buffer widths of 50 feet generally will provide adequate protection from suspended solids for maintaining high water quality. The data for phosphorus removal shows a slightly stronger, although not statistically significant, trend. Buffers wider than 60 feet showed considerably greater total phosphorus reductions than narrower buffers (69 percent of those buffers reduced total phosphorus by more than 70 percent). Another major function of wetland buffers is providing wildlife habitat. Recommendations in the literature for wetland buffer maintenance for optimal wildlife functions range from an absolute minimum of 50 feet up to 600 feet. In general, wider buffers are suggested as providing greater wildlife benefits. Reasonable wildlife benefits can be realized with the retention of 100-foot wide buffers. Several communities in the Twin Cities Metropolitan area have enacted wetland buffer ordinances with required buffer widths up to 100 feet. 1.4.3 Wetland Sequencing and Mitigation Standards The wetland sequencing and mitigation standards presented are suggestions based on interagency discussions and experiences with Comprehensive Wetland Management Plans. The goal of the recommended standards is to provide incentives to protect high quality wetland resources while realizing that low quality wetlands would not receive as stringent protection. There are specific standards that must be met according to state and federal rules (WCA, 404, etc.). They can be varied by local plan and these management standards could serve as a basis, but not a substitute, for a local plan. Some management prescriptions suggested here could be implemented without a formalized local plan but all local, state, and federal rules would still apply. The COE could use these standards to vary replacement ratios on a case-by-case basis. 1.4.4 Stormwater Treatment Standards Stormwater treatment management standards were developed to protect wetlands from water quality impacts. Various levels of pre-treatment of conveyed stormwater are recommended based on wetland management classification. 9 EOR, 2001 Management Classification 9