The Minneapolis Park and Recreation Board (MPRB) performs and documents extensive water quality monitoring and data collection as part of efforts to protect and care for the 13 lakes, three creeks and the Mississippi River in Minneapolis.
The Annual Water Resources Report is a comprehensive technical reference of water quality information. The report is available on the MPRB website as well as at Minneapolis public libraries.
Lake Water Quality Monitoring Program
MPRB monitors Minneapolis lakes for water quality to track trends, as long-term monitoring is important because lakes can change from year to year. Analyzing years of data together must be done to see trends that will determine if the water quality is improving or not. This is also used to develop water quality goals and evaluate the effectiveness of Best Management Practices.
The Minneapolis Lake Water Quality Monitoring Program began in 1991 as part of a study for the Chain of Lakes Clean Water Partnership, including Brownie, Bde Maka Ska, Cedar, Harriet and Isles, Diamond, Hiawatha, Loring, Nokomis, Powderhorn, Webber, Wirth and Spring Lakes.
Stormwater can contain waterfowl and pet waste, which can contribute to increased bacteria levels in the Mississippi River, as well as the lakes and creeks of Minneapolis.
Water from public beaches is monitored weekly and checked for bacteria throughout the summer, as high bacteria levels can pose a health risk for swimmers. If high bacteria levels are present in the water samples from a public beach, MPRB may close the beach until the water is safe for swimming.
Best Management Practices (BMP) Monitoring
Public Works first installed grit chambers in 1915, and currently maintains 145 grit chambers. Private grit chambers exist in Minneapolis, as well as grit chambers owned by Hennepin County and the Minnesota Department of Transportation.
Grit chambers are large underground concrete boxes with baffles, which allows the water to slow down, while sediment and heavy materials settle to the bottom of the chamber before exiting. All grit chambers remove sediment, trash and debris from stormwater runoff, keeping this material out of receiving surface waters, while some grit chambers filter stormwater as well.
Public Works and MPRB began monitoring grit chambers in 1998, developing goals that include:
- Measure effectiveness for specific units and applications
- Determine optimal cleaning schedules (If the chamber is full, the device will stop working, possibly resulting in material washing out of the grit chamber)
- Develop specification requirements and selection criteria for future installations, for both public and private construction in Minneapolis
The following list shows additional MPRB monitoring and water quality data collection:
- NPDES stormwater monitoring
- Watershed outlet monitoring programs
- Wetland health evaluations
- Stream bank erosion surveys
- Beach studies
- Lake levels
- Minnehaha Creek levels
- Ice on/out dates
- Rain data
- Macrophyte (algae that is visible to the naked eye) surveys
- Macroinvertebrate (aquatic animals without backbones visible to the naked eye) surveys
- Winter dissolved oxygen monitoring
- Audubon certification monitoring
- Groundwater and drinking wells
- Irrigation and augmentation wells
Additional monitoring is performed by individual watershed management organizations in Minneapolis.