5.2. SR 09-08-1997 - Laserfiche WebLink

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Minnesota Department of Natural Resources 500 Lafayette Road St. Paul, Minnesota 55155-40__ 10 August 13, 1997 Stephen Rohlf, Administrator Elk River Building & Zoning 13065 Orono Parkway Elk River, MN 55330 RE: Elk River Urban Service Area Environmental Assessment Worksheet (EAW) Dear Mr. Rohlf, The Department of Natural Resources (DNR) has reviewed the EAW for the Elk River Urban Service Area project. We offer the following comments for your consideration, which focus upon how the project could affect the water quality of the Mississippi River, specifically pollutant and nutrient loading from stormwater runoff originating from the development area. The Mississippi River is designated as a Wild and Scenic River at this stretch and supports an excellent smallmouth bass fishery from the site to (at least) Dayton, Minnesota. Therefore, project aspects that could influence the Mississippi River's water quality, and therefore affect the quality of this fishery, are of concern to DNR. Item 18, Surface Water Runoff, indicates the projected 25 % increase in runoff production will be treated through a combined use of sedimentation ponds and wetlands prior to discharge to natural waters. Although such an approach can prove effective, it is uncertain how effective the approach will be given the level of detail available in the EAW. In general, the success of runoff retention and treatment depends greatly upon the rate of discharge from the sedimentation basins to the wetlands in question. Also, to provide adequate treatment, detention times within the basins should be sufficient to allow the settling of most of the runoff's sediment load. It should be noted that the capacity of wetlands to "filter out pollutants" and nutrients prior to discharge to Trott Brook is limited. Historically, the land in the project area has been in agricultural use and ag-related runoff has been entering the wetlands. Given this history, the ability of these wetlands to serve the proposed function of "filtering out pollutants" associated with new development (i.e., lawn chemicals, road salts, dust, oil, greases, household chemicals)may be limited. We recommend that runoff quality reflect improvement relative to the current condition. Use of nutrient loading models run on similar wetlands may offer an opportunty to determine the loading potential to downstream waters so that improvements to runoff quality can be realized. Thank you for the opportunity to review this project. We do not recommend preparation of an environmental impact statement (EIS) based upon natural resource considerations. We look forward to receiving your record of decision and responses to comments. Minnesota Rules part 4410.1700, DNR Information: 612-296-6157, 1-800-766-~000 · TTY: 612-296~5484, 1-800-657-3929 An Equal Opportunity Employer ~,.~ Printed on Recycled Paper Containing a Who Values Diversity ~l~l~ Minimum of 10% Post-Consumer Waste