1311-004 Central Park Lake Watershed Final Report

(2016) 1311-004 Central Park Lake Watershed Final Report. Agriculture and Land Stewardship

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Abstract

The Central Park Lake Watershed Assessment and Management Plan identified four categories where improvements are needed to remove the 23 acre lake from the impaired waters list. These include the wastewater system, runoff from surrounding lands, in-lake nutrient re-suspension and runoff from hard surfaces within the park. The lake is currently impaired for bacteria, algae and pH. Through outcomes of the Watershed Assessment and Management Plan, this proposal includes the construction of two sediment and nutrient retention basins in the most critical drainages in the watershed affecting Central Park Lake. These two retention basins will treat and filter runoff from 218.1 acres, or 56% of the lake watershed. They are estimated to reduce sediment flow into the lake by 479.6 tons per year, reducing the annual sediment flow by 84%. By reducing the sediment loading by 84%, nutrient loading from particulate phosphorus will also be significantly reduced, leading to a reduction in algae concentrations and de-listing of the lake as an impaired water. This project is part of a $1.7 million lake restoration effort to reclaim the 47 year old lake. The lake has a positive economic impact of more than $7.3 million annually and supports an average annual visitation of 58,145, according to the Iowa Lakes Valuation Project, conducted by Iowa State University.