General water quality concerns Historical perspectiveLocal water quality goalsWater quality standardsRegional patterns in sediment phosphorus and
nitrogen pollutionReasons for differences among watershedsSources of pollutionImplementation strategyEffects of BMP's on water quality
The Minnesota River basin encompasses a large area in the state of Minnesota covering roughly 10 million acres, with approximately 700,000 rural, municipal, and urban residents. It drains 12 major watersheds. The predominant land use in the basin is agricultural.
Like many Minnesotans, you may be concerned about water quality in the Minnesota River basin. You may have heard that it is ranked as one of twenty rivers in America which is seriously threatened by pollution. During spring and summer especially, water quality in the Minnesota River can be severely impacted by:
Concerted efforts are needed by town dwellers, farmers, municipalities, and industries to reduce pollution of the river and its tributaries. Degraded water quality in the Minnesota River has a significant impact locally, as well as regionally and nationally.
Regional effects are common during summer when the river is low, in both Lake Pepin and the Minnesota River between St. Peter and Ft. Snelling. Further downstream, there is growing concern that the hypoxic zone (an area of very low dissolved oxygen levels in water) in the Gulf of Mexico is caused by nitrate nitrogen from the Upper Mississippi basin, including the Minnesota River basin. Low oxygen levels in water, whether fresh or sea water, causes fish and other organisms to die.
While the public has a right to expect improved water quality in the Minnesota River, goals need to be realistic. The Minnesota River never will be a crystal clear running stream. Serious degradation in water quality has, however, occurred in the Minnesota River over the last 150 years due to significant changes in land use. The Minnesota River basin once was a prairie and wetland landscape that supported a thriving population of birds and bison. As European-Americans moved in, they established many towns and cities, plowed the prairie, and drained the wetlands. The Minnesota River basin is now dominated by two major features. First is the vast agricultural landscape which contributes billions of dollars to the economy of Minnesota. Second is the large urban population center of the Twin Cities at the mouth of the Minnesota River where it enters the Mississippi River. Approximately 700,000 people live in the Minnesota River basin. These two features help explain the poor water quality and loss of wildlife habitat in the Minnesota River basin.
Goals for the river clean-up are often driven by concerns about local water quality. The day to day concerns of people for the river could include the following questions:
These concerns have less to do with water quality standards and more to do with quality of life. People want to use and enjoy the rivers. People are also concerned about specific areas within the broader watershed. For instance, there may be strong local concern about an individual lake or small stream.
These concerns can be used to develop local water quality goals as citizens and landowners develop local organizations which work cooperatively through individual county Comprehensive Local Water Plans and watershed management projects. To enhance this effort, the Minnesota River Basin Joint Powers Board has endorsed a strategy known as "Watershed Implementation from the Local Level" (WILL), designed to build on the framework of individual county water plans. After a WILL watershed management plan is developed in each of the major watersheds of the Minnesota River Basin, its goals and objectives will become part of individual county water plans. Together these 12 WILL plans will become the implementation "road map" for the Minnesota River Basin.
While local perceptions about the river are important, the state and federal governments have developed specific water quality standards for rivers that indicate the extent of pollution. Water quality in the Minnesota River and its tributaries has been monitored by collecting several hundred samples at various locations by state and federal agencies for the last 30 or so years. The key water quality standards for rivers are given below, along with a listing for the percent of water quality monitoring samples which violate these standards (Table 1):
Table 1: Percent of water quality monitoring samples taken in the Minnesota River at various locations from 1968-1994 that violate water quality standards for fecal coliform bacteria, turbidity, nitrate and nitrite nitrogen, and dissolved oxygen. Also, percent of samples for total phosphorus that exceed 0.25 mg/L, the mean concentration in the river.
| Parameter | Fecal | Turbidity | Nitrate and | Dissolved | Total |
| Coliform | Nitrite -N | Oxygen | Phosphorus | ||
| Water Quality Standard | 200 CFU/100 mL | 25 NTU | 10 mg/L | 5 mg/L | none* |
| Minnesota River Location | |||||
| % of samples violating standard | |||||
| near Milan | 2 | 16 | 0 | 4 | 31 |
| near Morton | 31 | 24 | 0 | 0 | 37 |
| near Courtland | 52 | 36 | 1 | 1 | 60 |
| near St. Peter | 48 | 42 | 10 | 1 | 63 |
| near Jordan | 31 | 38 | 11 | 0 | 37 |
| near Shakopee | na | 36 | na | 2 | 33 |
| near Ft. Snelling | 32 | 33 | 5 | 4 | 73 |
* Values in this column represent the percent of samples that exceed 0.25 mg/L, the mean concentration of total phosphorus in the Minnesota River.
Low dissolved oxygen levels are often caused by the decay of algae, which grow rapidly in water with high levels of phosphorus. There are currently no state-wide water quality standards for phosphorus levels in rivers. Streams and rivers in the Minnesota River basin have an average phosphorus concentration of 0.25 mg/L, and this level is frequently exceeded in the Minnesota River near Ft. Snelling and between Courtland and St. Peter (Table 1).
Table 1 shows the percent of water quality samples that violate standards. According to Table 1, water quality standards in the Minnesota River downstream of Morton are frequently violated, causing local concerns for human health, and affecting fish and other aquatic life. Major reductions in pollution from all sources will be required to protect human and aquatic health, to meet water quality standards, and address local concerns for pollution. To help achieve these pollution reductions, an interim target for a 40% reduction in sediment and phosphorus loads entering the Minnesota River and its tributaries has been recommended by state and federal agencies, and endorsed by the Minnesota River Basin Joint Powers Board. Specific goals for other pollutants will be established in the future.
Water quality standards are frequently violated in the Minnesota River from Morton downstream to Ft. Snelling, as well as in the tributaries to the river. Thus every one of the 12 major watersheds in the Minnesota River has local effects on water quality. There are, however, differences in the regional effects of each watershed on pollution in the Gulf of Mexico, Lake Pepin, or the stretch of the Minnesota River near the Twin Cities. The primary parameters of concern at the regional level are sediment, phosphorus, and nitrogen.
Water quality monitoring data collected by various state and federal agencies from 1968-1994 provide a comprehensive framework for understanding which watersheds have the largest regional effects. Sampling locations for this analysis were mostly at the mouth of major tributaries near the point where they enter the Minnesota River.
The loads of total suspended solids (TSS) in the Minnesota River at Ft. Snelling are controlled primarily by three watersheds. These are the Blue Earth and Le Sueur watersheds, and the Lower Minnesota watershed, which includes contributions from Rush River, and from High Island, Sand and Bevens Creeks. Combined, the Blue Earth, Le Sueur, and Lower Minnesota watersheds drain an area which represents roughly 25% of the total area in the Minnesota portion of the basin. This relatively small area generates two-thirds of the TSS load in the Minnesota River upstream of Ft. Snelling. The rough breakdown for TSS loads generated is:
Sediment loads from the other nine watersheds generate one-third of the basin wide load. This is an important load, and causes significant impacts on local water quality. The sediment loads from these nine watersheds cannot be overlooked in efforts to clean up the Minnesota River basin.
Roughly 64% of the total phosphorus (TP) load at Ft. Snelling comes from the Lower Minnesota, Le Sueur, and Blue Earth watersheds. The distribution of phosphorus loads in these three watersheds is:
From 1968-1994 about one-third of the phosphorus generated in the Lower Minnesota watershed was produced by the Blue Lake and Seneca wastewater treatment plants. Recently, biological phosphorus removal procedures have been adopted at these plants which has reduced phosphorus loads from wastewater effluent by 60-70%.
The other nine watersheds in the basin drain three-fourths of the total basin, and generate one-third of the total sediment and phosphorus loads. Again, loads from these nine watersheds have important local water quality effects, and cannot be overlooked in efforts to clean-up the Minnesota River basin.
Roughly 63% of the nitrate-nitrogen load at Ft. Snelling comes from the greater Blue Earth watershed, which includes the Blue Earth, Le Sueur, and Watonwan watersheds. The distribution of nitrogen loads in these three watersheds is:
Three other watersheds, namely; the Lower Minnesota, Middle Minnesota, and Cottonwood watersheds generate another 31% of the nitrate-N load.
Results of the sediment and phosphorus evaluation for the Minnesota River basin show significant increases in both loads and yields going from the western to eastern portion of the basin. The three primary reasons for this increase from west to east are:
Pollutants of concern in the Minnesota River basin include bacteria and other disease causing organisms, suspended sediments, excess nutrients, and decaying organic matter responsible for low levels of oxygen. These pollutants come from a variety of sources including runoff and erosion from agricultural fields, stream banks and stream channel scouring, city streets, construction sites, feedlots, and the effluent from wastewater treatment plants and septic systems.
There are significant agricultural and non-agricultural sources of pollution that degrade water quality in the Minnesota River basin. To the best of our knowledge, municipal and industrial wastewater discharges account for about 10% of the loading during high flow years, and for about 65% of the total phosphorus loading in the Minnesota River during low flow years. Indirect measurements suggest that non-agricultural sources of sediment (stream bank erosion, erosion from construction sites) account for about 25% of the total sediment loading in the Minnesota River. These estimates are subject to refinement as better information becomes available. These data show that both point-source and non-point source efforts are going to be required to clean up the Minnesota River.
A clean-up strategy must target the locations in the basin which have the greatest impact on water quality, as well as the most important sources of water quality degradation. The most important sources of pollution are:
There are about 179 municipal wastewater treatment plants and 103 industries in the Minnesota River basin which, taken together, discharge significant quantities of phosphorus. Occasionally, these plants may malfunction, discharging bacteria into surface water. It is estimated that there are also 30,000 septic systems in the basin which illegally discharge bacteria and pathogens directly to tile drains, ditches, and streams. Minnesota spends millions of dollars every year to reduce pollutants in the effluent from municipal wastewater treatment plants and from septic systems.
Minnesota agricultural producers also spend millions of dollars every year on a wide array of Best Management Practices (BMPs) for agricultural land. Since agricultural production contributes several billion dollars annually to Minnesota’s economy, any changes in agricultural management practices made for the sake of improving water quality in the Minnesota River must be economically feasible and reasonable. Some of the BMPs most effective at protecting water quality include:
The BMP selected will depend upon site specific characteristics, as well as individual attitudes and financial or labor constraints. Assistance in selecting among the various BMPs can be obtained from the Minnesota Extension Service (MES), Soil and Water Conservation Districts (SWCD), Minnesota Department of Agriculture (MDA), the Natural Resources Conservation Service (NRCS), or the Minnesota Pollution Control Agency (MPCA).
There are reasons to be optimistic about improving water quality in the Minnesota River and its tributaries. Recent studies by the University of Minnesota and the MPCA found a significant reduction in sediment and phosphorus loads in the Minnesota River during the last twenty years. This improvement was due to a combination of factors including: accelerated adoption of BMPs by farmers (including conservation tillage), improved manure management, the installation and upgrading of wastewater treatment plants, and septic system improvements. Just in the last year, there have also been significant reductions in phosphorus concentrations of effluent from the Blue Lake and Seneca wastewater treatment plants. These results show that it is possible to clean up the Minnesota River by adoption of BMPs and by improved waste management and wastewater processing. Additional efforts are needed so that Minnesotans can regain their pride in a Minnesota River that is swimmable, fishable, and unpolluted.
This document was created in partnership with the following groups: University of Minnesota Extension Service, Minnesota Agricultural Experiment Station, Minnesota River Basin Joint Powers Board, Minnesota Pollution Control Agency, Minnesota Department of Agriculture, Minnesota Board of Water and Soil Resources, U.S. Geological Survey, Minnesota Department of Natural Resources, USDA Natural Resources Conservation Service, Metropolitan Council Environmental Services, Mankato State University Water Resources Center, Minnesota River Citizens Advisory Council, and Coalition for a Clean Minnesota River. Data processing, graphics and formatting by A.P.Mallawatantri, and technical editing by D. J. Mulla, Dept. Soil, Water, and Climate, University of Minnesota.
