Minnesota Milestone River Monitoring Program

Minnesota may be home to 10,000 lakes, but it is also home to more than 92,000 miles of rivers! Minnesota is also home to the headwaters of one of the most important rivers in the World; the mighty Mississippi. The rivers in Minnesota are important for recreation, transportation, agriculture, drinking water, and wildlife. Minnesota’s rivers are one of our most treasured and valuable natural resources so the need to monitor and protect them is essential.

About the Minnesota Milestone Program

The Minnesota Milestone Program was designed to collect water quality data at designated river sites over a long period of time. This data is then used to get an understanding of the overall health trends of Minnesota’s rivers. The Minnesota Milestone Program was eliminated in September 2010 and replaced with an intensive watershed approach of assessing the rivers in Minnesota.

History

The Water Pollution Control Commission was monitoring the water in Minnesota's streams starting in 1953. The Minnesota Pollution Control Agency took over this duty in 1967, when it was created. The current sites and sampling rotations were selected in 1994. The river sites were selected based on how well they represent a particular river reach and were not selected to monitor any particular pollution source. Many sites had been monitored since 1953, although some sites were dropped and others added over the years based on the amount and quality of previous data.

Chemicals Analyzed and Data Collected at Milestone Sites

The Minnesota Milestone Program sampled each of the ten Minnesota basins twice in a five-year period. The river sites in that basin were then sampled monthly for one year. (January 15 through December 1). The chemicals analyzed changed slightly throughout the years although the following chemicals were almost always checked year-round:

• transparency
• turbidity
• conductivity
• nitrogen
• temperature
• pH levels
• dissolved oxygen

Sometimes other parameters were measured if another MPCA study was ongoing. The following parameters were commonly measured:

• fecal coliform
• E. coli
• chlorophyll
• total suspended solids
• biological oxygen demand
• mercury
• phosphorus
• chloride
• sulfate
• carbon
• color

Also, most sites have some method of determining the water level at the time of the sampling. Some of the methods include taking a tape-down reading from an established location, using an installed wire-weight, or using an automatic gage installed at the site. This information can help in determining the flow during the sampling.

The data collected is stored in a database that can be used by researchers, professors, students, water planners, interested citizens and environmental agencies all over the country to use. To view data specific to the Minnesota Milestone Program, visit the Minnesota Milestone Monitoring Sites web page.

Detailed Descriptions of Parameters Measured

Transparency. The transparency measurement provides information as to the clarity of stream water; how much sediment, algae, and other materials are suspended in the water.

Turbidity. The turbidity of water is attributable to suspended and colloidal matter, the effect of which is to disturb clearness and diminish the penetration of light. It is a measure of the extent to which the intensity of light passing through the water is reduced by the suspended colloidal matter. Turbidity may be caused by micro-organisms or organic detritus, silica or other mineral substances, including zinc, iron, and manganese compounds, clay or silt, industrial and municipal wastes, and natural erosion products. High turbidity has the following effects: It is esthetically undesirable with respect to recreational use and palatability of water, interferes with industrial processes such as laundries, laundering, bottling beverages, brewing, production of various textiles, production of pulp and paper, is lethal to fish life at very high concentration, interferes with biological productivity, and modifies the temperature structure of ponds.

Conductivity. Conductivity is the measurement of electrical current flow. Pure water has very low conductivity because it has few contaminants to conduct an electrical current flow. When water is contaminated, the foreign molecules dissociate easily in the presence of water and create positively and negatively charged ions. These charged ions conduct electricity and therefore increase the conductivity of the water. Thus conductivity is an indirect measure of the level of contamination in the water.

Nitrogen. Nitrogen is a nutrient required for the growth of terrestrial and aquatic plants. While phosphorus is usually the nutrient limiting growth of aquatic plants, nitrogen may be the limiting nutrient in some situations. Certain forms of nitrogen, however, may also be toxic to various organisms. Toxicity concerns are described in the descriptions of the specific nitrogen forms. The nitrogen cycle is quite complex in that several forms of nitrogen are present in the environment. The presence of these forms is affected by biological, chemical, and physical processes including oxidation state, temperature, pH, and bacteria. Evaluation of the concentrations of each form can sometimes be used to assess how recent or how far from the sampling site the pollution source was located (State of Washington 1988).

Nitrogen, Kjeldahl, Total. Total kjeldahl nitrogen (TKN) provides a measure of the free-ammonia and organic nitrogen in water (USEPA 1983). TKN concentrations may be used in project analyses; however, it is more commonly used as an intermediate value to calculate the concentrations of other forms of nitrogen. The total amount of nitrogen in water is usually considered to be the sum of the TKN and nitrate+nitrite nitrogen concentrations. Organic nitrogen concentrations are calculated by subtracting the ammonia nitrogen concentration from the TKN concentration.

The total amount of nitrogen present is used to compute phosphorus; nitrogen ratios for lakes to document which nutrient is probably limiting algae growth. Organic nitrogen concentrations are useful primarily in indicating the presence of organic pollutant sources.

TKN concentrations are dependent on biological activity and the sources of the pollution. Given a certain pollutant load, TKN will tend to decrease with time as ammonia nitrogen is converted to nitrate and nitrite nitrogen. Factors to consider when evaluating the nitrogen compounds include type of pollutant source, source location, water characteristics (temperature, dissolved oxygen, depth, velocity), season, and bacterial activity.

Nitrogen, Ammonia, Total

Un-ionized Ammonia. Ammonia-nitrogen (NH 3-N), an inorganic form of nitrogen, is contained in fertilizers, septic system effluent, and animal wastes. It is also a product of bacterial decomposition of organic matter. NH 3-N becomes a concern if high levels of the un-ionized form are present. In this form, NH 3-N can be toxic to aquatic organisms. The presence of un-ionized ammonia is a function of the NH 3-N concentration, pH, and temperature. Conversion of NH 3-N to nitrite nitrogen by nitrification requires large quantities of oxygen which can kill aquatic organisms due to the lowered dissolved oxygen concentrations in water.

Changes in concentration are a result of pollutant loading, bacterial decomposition of organic-N to NH 3-N, and oxidation of NH 3-N to nitrite nitrogen. These changes are affected by the type of pollutant source, source location, water characteristics (temperature, dissolved oxygen, depth, velocity), season, and bacterial activity.

Due to the bacterial conversion of NH 3-N to nitrate and nitrite nitrogen, the proximity of a sampling station to a nutrient source will affect analysis results. If a station is located close to an NH 3-N source, NH 3-N levels may be high while nitrate+nitrite nitrogen concentrations are not elevated. Conversely, if a station is located far enough downstream for biological activity to have converted most of the NH 3-N, the NH 3-N concentration may be low and the nitrate+nitrite nitrogen high (State of Washington 1988).

Nitrogen, Nitrate plus Nitrite. Nitrate and nitrite are inorganic forms of nitrogen present in the environment. They are formed through the oxidation of NH 3-N by nitrifying bacteria (nitrification). They are converted to other nitrogen forms by denitrification and plant uptake. While nitrate is one of the primary forms of nitrogen used by plants for growth, the greatest pollution concern is high nitrate concentrations in drinking water which can result in methemoglobinemia (“blue baby syndrome”). The primary concern for high nitrate levels is found in ground water. Nitrite concentrations are generally small in natural waters and, therefore, not a major concern for individual analysis. For this reason, laboratory analysis of these is combined as nitrate plus nitrite nitrogen (NO 3 + NO 2 - N).

NO 3 + NO 2 - N concentrations vary seasonally with biological activity and nutrient inputs. The factors affecting concentration variations are the same as described above for TKN and NH3-N. These factors should be considered when evaluating sampling results.

Temperature. Water temperature affects aquatic productivity, lake stratification, and water chemistry. Temperature extremes are especially important in determining productivity of aquatic life from algae to fish. Temperature combined with lake morphometry and other physical or climatic factors affects the mixing characteristics of lakes. Temperature affects water chemistry, including the levels of DO and un-ionized ammonia.

Temperature varies spatially and temporally. Stream temperatures will vary due to air temperature, water sources, water velocity and depth, and streambank cover. Lake temperatures will vary due to air temperature, water sources, depth, and mixing characteristics of the lake. These factors should always be considered in sampling site selection and data interpretation.

pH. pH is a term used to express the intensity of the acidity or alkalinity of a solution. It is obtained by measuring the activity of hydrogen ions (H+). pH is impacted by the types and concentrations of acids and bases in the water. pH affects the toxicity, reactivity, and solubility of many chemical compounds, and thus has a wide impact on the relative health of the water system. pH values should not go below 6.0 or above 9.0.

pH is affected by various environmental factors. A few of these factors include changes in production and respiration rates of aquatic plants and animals, type of water body, and physical watershed characteristics. Care in sampling and analysis is needed to provide consistency in the measurements over time and location of sampling

Dissolved Oxygen. Dissolved oxygen (DO) is important because adequate DO concentrations are needed for the growth and reproduction of fish and other aquatic life, DO plays an important role in the chemistry and natural degradation of pollutants in a water body, reduced DO concentrations can lead to taste and odor problems in water and DO concentrations in ground water yields information on recharge/discharge relationships, potential nitrate formation, and the chemical stability of a discharging water well.

Bacteria. The most common type of bacteria which is monitored in rivers and lakes is fecal coliform and fecal streptococcus, which are present in the intestines of all warm-blooded animals, including humans. These bacteria are obviously not harmful to animals or humans, but they do indicate that sewage contamination has occurred and suggests the presence of disease-causing bacteria and viruses such as E. Coli, salmonella, and cryptosporidium.

Considerations: The presence of fecal coliform and fecal streptococcus bacteria in water is affected by several environmental factors, including sunlight, nutrient levels, temperature, amount and character of sediment, predation by other organisms, flow, and amount of runoff. The proximity of the sampling station to upstream pollution sources along with the environmental factors listed above will influence bacteria concentrations in water. These factors will vary spatially and temporally and, therefore, should be considered in sampling site selection and data interpretation (State of Washington 1988).

Chlorophyll- a. Chlorophyll-a is the most common biological parameter measured in lake monitoring in lake monitoring programs. To help standardize the data, it is recommended that chlorophyll-a samples be collected from the top two meters of the water column with an integrated sampler.

Chlorophyll-a samples must be filtered through a glass-fiber filter immediately in the field and then the filter should be frozen and stored in a dark container (wrap with aluminum foil) until analyzed. Use stainless steel forceps when handling the filters. If raw water samples are simply cooled and stored for a period longer than a few hours prior to filtration, pigment can break down. Under no circumstances should raw water samples be held longer than 24 hours or frozen prior to analysis.

Total Suspended Solids. Total suspended solids (TSS) is a direct measurement of the concentration of suspended particulates, inorganic and organic, in water. Particulate matter directly affects aquatic environments by decreasing light availability, interfering with the filter feeding mechanisms of aquatic animals, and covering bottom habitats. Other pollutants are also often absorbed on to the particulate matter. These pollutants include nutrients, pesticides, other organics, bacteria, and metals.

Considerations: TSS concentrations vary with physical factors such as soil and land cover characteristics, quantity of runoff, and stream flows. Changes in these factors over time and space must be considered in sampling site and frequency selection and resulting data interpretation. Mass loading calculations, using TSS concentrations and corresponding stream flows, are important in evaluating the magnitude of particulate sources.

Biochemical Oxygen Demand. Biochemical oxygen demand is a non-specific measure of the organic matter in waste or water which can be degraded and utilized for food by living organisms. In effect, the organic matter is oxidized by these organisms, and dissolved oxygen is used in the process. A high biochemical oxygen demand may result in the complete depletion of the dissolved oxygen in the water followed by fish kills and the growth of anaerobic organisms which, in turn, produce unpleasant odors. However, a high biochemical oxygen demand may be offset by a high rate of re-aeration so that the actual dissolved oxygen in the water is maintained at satisfactory levels. Biochemical oxygen demand limits cannot be set without consideration of re-aeration rates.

However, even if oxygen can be maintained, the high concentrations of organic matter reflected by high biochemical oxygen demand can produce high bacteria populations, turbidity, and other undesirable effects.

Heavy Metals. The heavy metals are among the most harmful of all of the elemental pollutants. These metals, which are in general the metals in the lower right hand corner of the periodic table, include essential elements like iron, as well as toxic metals such as arsenic, cadmium, chromium, copper, lead, mercury, and selenium.

Most heavy metals have a high affinity for sulfur and attack sulfur bonds in enzymes, thus immobilizing the enzymes which are essential for many cellular activities. Cadmium, copper, lead, and mercury ions bind to cell membranes which can hinder important transport processes through the cell wall. The major health effects that have been associated with heavy metals are neurological damage and reproductive effects.

Polychlorinated Biphenyls. Polychlorinated biphenyls (PCB’s) are very stable materials of low flammability, which contain from 12 to 68 percent chlorine. They are exceptionally persistent in the environment. In the past, they have been used as insulating materials in electrical capacitors and transformers, as plasticizers in waxes and paper manufacturing, and for a variety of other industrial purposes.

Although PCB’s are no longer produced in the United States, a number of factors have led to their widespread occurrence in soil and water. Three main factors accounting for their distribution in the environment are their chemical diversity, the large quantities that were produced, and their stability. Investigators have shown that PCB’s interfere with reproduction in wildlife and in experimental animals. Other adverse effects are possible because of the tendency for PCB’s to accumulate in fat tissue.

Phosphorus, Total. Phosphorus is present in the environment in several forms. The analysis for total phosphorus (TP) provides a measure of the total concentration of phosphorus present in a water sample. Only a portion of the TP is readily available for use in algae growth; however, TP does give an indication of the total amount of phosphorus contained in the various forms of phosphorus. TP is also used in many eutrophication models.

Considerations: TP concentrations are affected by biological, chemical, and physical activity, as well as the various inputs described above. Variations in concentration caused by these things can be expected spatially and temporally. These changes must be considered in sampling site and frequency selection and resulting data interpretation. Mass loading calculations at stream sites, using TP concentrations and corresponding stream flows, are important in evaluating the magnitude of phosphorus sources.

Ortho Phosphorus. Soluble reactive phosphorus consists of the dissolved, inorganic phosphorus in the water. Soluble reactive phosphorus is often referred to as orthophosphorus (OP). It is the only phosphorus compound readily available for use by algae or other aquatic plants. As such, it provides a measure of the phosphorus immediately available for plant growth. Particulate, inorganic and organic forms of phosphorus can be transformed for use by plants, but the rates are dependent on various factors. The sum of the amounts of particulate, inorganic and organic phosphorus present can be determined by subtracting the OP concentration from the TP concentration.

Chloride. Chloride is a binary compound of chlorine, a highly irritating greenish-yellow gaseous halogen capable of combining with nearly all other elements. Chlorine is produced principally by electrolysis of sodium chloride and used widely to purify water and as a bleaching agent. Chloride is present (generally as sodium chloride) in all natural waters, although the concentration can vary from a few milligrams per liter or less, to several thousand milligrams per liter in some ground waters. Reasonable amounts of chlorides can be tolerated in many industrial waters and in potable supplies. The chloride ion is small, highly mobile, and will accelerate corrosion reactions in proportion to its concentration because of its ability to penetrate and increase solution rate of iron, and its contribution to electrolyte content. For this reason, brines can corrode a system at a rapid rate. Chlorides can accelerate stress corrosion of stainless steel allows and must be carefully controlled in systems where these metals are used. Recent testing of the toxic action of hydrogen-ions on fish show that the toxic effect of acid pH values is enhanced at low concentrations of sodium and chloride. The addition of sodium chloride to raise the sodium content increased the survival of several species.

Pollution Trends at Milestone Sites

• . These maps show whether or not there has been a trend, over the last 40 years, for particular parameters.
• Milestone Trends by Decade (milestonetrendsbydecade) - This spreadsheet shows the average values, by decade, over the last 40 years at each site for particular parameters.
• for streams are prepared to estimate the extent that they will meet federal and state water quality standards.

Common Pollution Sources

Source: Wisconsin Extension Service

Indicators of a Healthy River

• River water is cool and clear
• River flow is varied
• River meanders naturally with minimal erosion on banks
• River sustains diverse native plant and animal communities over time
• Abundant tree cover and vegetation to stabilize stream banks and keep water cool
• River is resilient to natural or man-made disturbances
• The watershed feeding the river is healthy

How You Can Help a River?

• Courtesy DNR Adopt-a-River Program
  Keep wastes away from streams and storm sewers such as motor oil, antifreeze, grass clippings, pet wastes and carpet cleaning water.
• Avoid draining pool water directly into a stream or storm sewer
• Wash vehicles on lawn to avoid soaps and vehicle grime from going directly into stream or storm sewer
• Practice good septic system maintenance
• Minimize use of pesticides and fertilizers
• Volunteer to mark storm drains with messages such as, “Don’t Pollute! Drains to River!”
• Clean-up debris in a river by “Adopting a River.”
• Volunteer to become a Citizen Stream Monitor.

Related River Links

• Adopt-A-River
• Wild and Scenic Rivers in Minnesota
• Mississippi River Critical Area Program
• Friends of the Mississippi River
• Metropolitan Council Rivers
• Citizen Stream Monitoring program
• American Rivers

More Information

If you need additional information or assistance, contact:

• Sandra Bissonnette, Minnesota Milestone Program, 651-757-2230
• Beth Endersbe, Minnesota Milestone Program, 651-757-2338