Photo caption: Algae in the Shell Rock River
Lakes and streams in the Shell Rock River watershed in southern Minnesota are suffering multiple stressors that hurt fish and other aquatic life, according to a study by the MPCA.
This drainage area totals about 254 square miles, all in Freeborn County, with the largest city being Albert Lea, population 18,000. The majority of the watershed is farmed for corn and soybeans with an extensive drainage system. Fountain Lake, in the center of Albert Lea, is popular for boating, fishing, and other recreation. Myre-Big Island State Park owns 40 percent of the shoreland of Albert Lea Lake, which is the first lake in Minnesota to greet travelers on Interstate 35.
High levels of nutrients
Excessively high levels of nutrients cause severe algal blooms that stress fish and aquatic life. Algal blooms also make the water unsightly and smelly for recreation. Some forms can even be harmful to humans and animals. The sources of nutrients include agricultural fertilizer running off or leaching from fields, manure runoff, and wastewater.
- Low or fluctuating levels of dissolved oxygen needed to sustain aquatic life.
- Low flows and high water temperatures during dry conditions contribute to fluctuations in dissolved oxygen levels.
- pH levels high enough to harm fish and other aquatic life by damaging gills and other effects.
- Lack of habitat due to sediment, which is soil and other particles that cloud the water and build up on lake and stream bottoms, making it hard for aquatic life to breathe, feed and reproduce.
- Imbalance of dissolved salts and minerals that can be toxic to aquatic life.
- Changes in stream flow to accommodate drainage.
To improve water quality in the Shell Rock watershed, the MPCA recommends:
- Major reductions in nutrient levels in the watershed’s streams and lakes by better management of fertilizer and manure throughout the watershed.
- The Albert Lea wastewater treatment plant will also need to remove more phosphorus from its discharge to the Shell Rock River.
- Preventing erosion from streambanks, driven by increased flow from drainage, to reduce the sediment levels in water bodies.
For more information
The MPCA and local partners will include more detailed recommendations in the Watershed Restoration and Protection Strategies, the document that culminates this first cycle of intensely studying the watershed.
Media coverage of the watershed: