Large river water quality monitoring

Today, Metropolitan Council Environmental Services monitors more than 150 river miles in the Twin Cities metro area via 15 long-term monitoring sites on 4 rivers: the Mississippi, Minnesota, St. Croix, and Crow rivers. We monitor these large rivers for a variety of physical, chemical, and biological variables. The goal is to document long-term changes in water quality and assess and characterize biological communities and riverbed sediments.
Large river water quality monitoring allows us to:

  • Measure compliance with state water quality standards and criteria
  • Meet National Pollutant Discharge Elimination System (NPDES) permit requirements
  • Assess the operations of our wastewater treatment facilities
  • Determine the biological health of large river ecosystems
  • Obtain information on the sources and water quality impacts of nonpoint source pollutants
  • Document long-term trends and changes in water quality

Large River Water Quality Monitoring Sites

Note: Automatic monitoring stations measure temperature, pH, dissolved oxygen, and specific conductivity at 15-minute intervals. Biological monitoring is conducted at 8 sites (6 on the Mississippi River and 2 on the Minnesota River) where macroinvertebrates are collected and sent to a lab for identification.

Water quality paramters and frequency of measurement

(Frequency is weekly during March – October and biweekly during November – February)
Frequency Analyte
Bi-Weekly Biological Oxygen Demand, Total (In-situ 5-day)
Biological Oxygen Demand, Carbonaceous (In-situ 5-day)
Weekly Temperature
Dissolved Oxygen
Specific Conductivity
Chloride, Total
E. coli
Fecal Coliform
Nitrogen - Ammonia
Nitrogen - Nitrate
Nitrogen - Nitrite
Nitrogen, Total Kjeldahl
Nitrogen, Total Kjeldahl, Dissolved
Phosphorus, Ortho, Dissolved
Phosphorus, Total
Phosphorus, Total Dissolved
Solids, Total Suspended
Quarterly Alkalinity, Total
Ions - Calcium, Dissolved
Ions - Magnesium, Dissolved
Ions - Silica, Dissolved
Ions - Sodium, Dissolved
Ions - Sulfate, Dissolved
Ions - Potassium, Dissolved
Solids, Total Dissolved
Carbon, Total Organic
Trace Elements - Aluminum, Total
Trace Elements - Antimony, Total
Trace Elements - Arsenic, Total
Trace Elements - Beryllium, Total
Trace Elements - Cadmium, Total
Trace Elements - Chromium, Total
Trace Elements - Copper, Total
Trace Elements - Iron, Total
Trace Elements - Lead, Total
Trace Elements - Mercury, Total
Trace Elements - Nickel, Total
Trace Elements - Selenium, Total
Trace Elements - Silver, Total
Trace Elements - Thallium, Total
Trace Elements - Zinc, Total

Additional resources