Minnesota's Impaired Waters and TMDLs
TMDL Project: Byllesby Reservoir — Excess Nutrients
Background
This project addresses two impairments for excess nutrients, Byllesby and Chub lakes, located in the Cannon River watershed in the Lower Mississippi River basin.
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.
Map and location
Byllesby and Chub lakes are located in southern Dakota County, within the Cannon River Valley, near Cannon Falls. These lakes are in the Cannon River watershed in the Lower Mississippi River basin.
- For a map containing Byllesby and Chub lakes, see the
Lower Mississippi and Cedar River Basins map (tmdl-lm-lakes-06).
TMDL report and implementation plan
The MPCA has prepared a draft report on the Byllesby Reservoir TMDL. The report is open for public comment May 13 – June 14, 2013. After receiving comments, revising the report and receiving federal approval of the report, the MPCA will work with local partners to develop strategies to reduce pollution throughout the watershed.
The Byllesby study included setting water quality standards specifically for the reservoir:
- 90 parts per billion (ppb) or less of total phosphorus. 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 parts per billion, well above state water quality standards.
- 30 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. Levels above 30 ppb are associated with severe algal blooms.
- Water clarity of at least 0.8 meter (2.62 feet). 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 (1.97 to 2.95 feet).
The MPCA believes these site specific standards will result in fewer and less severe algal blooms in the reservoir.
The study indicates that significant reductions in nutrients will be needed to meet these standards. Urban changes will include addressing stormwater runoff and reducing wastewater nutrient loads from communities in the watershed. Some cities, including Northfield, Faribault and Owatonna, have already taken steps to reduce phosphorus in their wastewater discharges. Rural changes will include managing manure and fertilizer as well as reducing erosion and runoff to local waters.
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Fact sheet on Byllesby Reservoir TMDL (wq-iw9-10i) - Lake Byllesby Site Specific Standard (wq-iw9-10h)
- Draft TMDL (wq-iw9-10b)
- Public Notice open for comment May 13 – July 15, 2013
- The public comment period has been extended to July 15, 2013.
Meetings and events
Mike Peterson, who farms in the Cannon River watershed near Northfield, is reaping benefits for his soil and for downstream waters from conservation practices. See his story in the MPCA’s Minnesota Water Stories online.
Northfield farmer David Legvold is using on-farm research to fine-tune his nitrogen applications to increase his profitability while reducing the impact downstream. See his story in the MPCA’s Minnesota Water Stories online.
Links
Information contact
Justin Watkins, Project Manager
Minnesota Pollution Control Agency
18 Wood Lake Drive SE
Rochester, MN 55904
507-206-2621
justin.watkins@state.mn.us