Minnesota Pollution Control Agency

Media contact: Cathy Rofshus, 507-206-2608 Rochester, Minn. -- A public comment period will be held from May 26 through June 26 on water-quality standards proposed for Byllesby Reservoir on the Cannon River in Goodhue and Dakota counties. The proposed standards are specific to the reservoir site and address nutrient levels and water clarity. Created by a dam in 1911, the Byllesby Reservoir is a shallow basin covering 1,400 acres. The land that drains to the reservoir totals about 730,000 acres, representing 1.3 percent of the State of Minnesota. With many boat accesses and two county parks, the reservoir is popular for swimming, boating and fishing. However, because of sediment, nutrients and other pollutants entering the reservoir, Byllesby suffers from cloudy water and algal blooms that harm fish and wildlife habitat. The lower water quality also decreases recreational opportunities. The Minnesota Pollution Control Agency (MPCA) with the Cannon River Watershed Partnership is conducting a study of the reservoir. This study, called a Total Maximum Daily Load, includes setting water-quality standards specifically for Byllesby. The MPCA is setting these standards because Byllesby presents unique conditions as a reservoir and because its watershed drains more than one type of geographic area. The proposed standards for summer months include:
-- Ninety parts per billion (ppb) or less of total phosphorus. Phosphorus is an essential nutrient for plants, but too much fuels algal blooms. Total phosphorus includes both the amount dissolved in the water and attached to sediment (soil) particles. Eight summers of measuring the levels in Byllesby found a range of 200 to 250 ppb, well over state water-quality standards.
-- Thirty ppb or less of chlorophyll-a, the main pigment in algae. The water-monitoring study found the average level in Byllesby to be 47 ppb, with about 60 percent above 30 ppb, a level associated with severe algal blooms.
-- Water clarity of at least 0.8 meter. Water clarity is an important measurement of a lake or river's health. The study found that water clarity in Byllesby ranged from 0.6 to 0.9 meter, with poor water clarity where water flows into the reservoir and better water clarity near the dam.
The MPCA believes these site specific standards will result in fewer and less severe algal blooms in the reservoir. If adopted, they will become part of the pollution study and cleanup plan for Byllesby. Details of the proposed standards can be found on the MPCA Web site at www.pca.state.mn.us/water/tmdl/tmdl-draft.html. To receive more information or submit comments on these site-specific standards for the Byllesby Reservoir, contact Justin Watkins, MPCA, 18 Wood Lake Drive S.E., Rochester, MN 55904; telephone 507-206-2621 or 800-657-3864; e-mail justin.watkins@pca.state.mn.us.