Watershed Pollutant Load Monitoring Network
The Watershed Pollutant Load Monitoring Network is a long-term program designed to measure and compare regional differences and trends in water quality from Minnesota’s rivers and the outlets of tributaries draining to these rivers.
Pollutant load monitoring sites in Minnesota
Click on the map to see details and data from the monitoring sites.
Overview
The Watershed Pollutant Load Monitoring Network (WPLMN) is designed to measure and compare regional differences and long-term trends in water quality among Minnesota's major rivers including the Red, Rainy, St Croix, Minnesota, and Mississippi and the outlets of major tributaries (8 digit HUC scale) draining to these rivers. Since the program's inception in 2007 with an appropriation from Minnesota's Clean Water Legacy Fund, the network has adopted a multi-agency monitoring design. Site-specific stream flow data from United States Geological Survey (USGS) and Minnesota Department of Natural Resources (DNR) gaging stations is combined with water quality data collected by the Metropolitan Council Environmental Services (MCES), local monitoring organizations, and WPLMN staff to compute annual pollutant loads at river monitoring sites across Minnesota.
Program goals
The Watershed Load Monitoring Network is tied to the goals of the 1972 Clean Water Act for restoring and protecting the multiple beneficial uses and ecological integrity of America's waters.
Primary goals:
- Measure and compare regional differences in water quality.
- Determine long-term trends in water quality.
Data will also be used to assist with: impaired waters assessments; watershed and water quality studies and reports; watershed modeling efforts: and to measure the ongoing effectiveness of major watershed protection and restoration plans.
Location of monitoring sites
There are currently 79 monitoring sites within the Watershed Pollutant Load Monitoring network. Design scale is focused toward but not limited to monitoring 8 digit HUC watershed outlets within the state (average drainage area 1,350 square miles). Watersheds contained primarily in neighboring states but with small drainage areas in Minnesota have been omitted from the monitoring network; and in regions where 8 digit HUC watersheds are lacking, smaller "indicator" watersheds have been added. Strategic major river mainstem sites have also been added to determine basin loads and assist with statewide mass balance calculations.
Monitoring strategy
Intensive water quality sampling occurs year-round at all WPLMN sites. Thirty to thirty-five mid-stream grab samples are collected annually at each site with sampling frequency greatest during periods of moderate to high flow. Because correlations between concentration and flow exist for many of the monitored analytes, and because these relationships can shift between storms or with season, computation of accurate load estimates requires frequent sampling of all major runoff events. Low-flow periods are sampled less frequently as concentrations are generally more stable when compared to periods of elevated flow. Despite discharge-related differences in sample collection frequency, this staggered approach to sampling generally results in samples being well distributed over the entire range of flows.
Water quality measurements collected include both field and laboratory measurements.
The in-field measurements include:
- pH
- temperature
- conductivity
- dissolved oxygen
- turbidity
- transparency tube
The laboratory measurements include:
- total suspended solids (TSS)
- suspended volatile solids (SVS)
- turbidity
- dissolved orthophosphate (DOP)
- total phosphorus (TP)
- nitrate plus nitrite nitrogen (NO3 + NO2)
- total kjeldahl nitrogen (TKN)
All labs used in the program are certified by the Minnesota Department of Health. Loads and flow weighted mean concentrations are calculated annually for total suspended solids (TSS), total phosphorus (TP), dissolved orthophosphate (DOP), nitrate plus nitrite nitrogen (NO3+NO2 -N) and total Kjeldahl nitrogen (TKN).
Data/Reporting
Databases
- DNR/MPCA Cooperative Stream Gaging Network - USGS, DNR, and MPCA – Stream discharge and links to Division of Waters Resources, climate information, river levels, water quality information, recreation, and commonly used hydrological terms.
- USGS – USGS discharge information.
- Environmental Data Access – Water quality data collected for all MPCA monitoring programs.
Reporting
- Long Term Average and Annual statewide water quality summaries - Flow-weighted mean concentrations calculated for total suspended solids (TSS), total phosphorus (TP), dissolved orthophosphate (DOP), total Kjeldahl (TKN), and nitrate plus nitrite nitrogen.
- Maps: Average (2007-2009); Annual (2007-2009)
- Data files:
2007-2009 Average Loads (wq-cm4-05) ; 2007-2009 Annual Loads - Watershed monitoring and assessment reports
- Minnesota Watersheds Monitoring and Assessment Report – click on each watershed to see the watershed report.
- Water quality trends – Several years of data are required to determine increasing and decreasing trends in water quality. Results are currently unavailable.
Procedures
Sampling procedures
Intensive water quality sampling, both in field and laboratory measurements, occurs year-round at all MWLM sites. Thirty to thirty-five mid-stream grab samples are collected per site per year with sampling frequency greatest during periods of moderate to high flow. Because positive correlations between concentration and flow often exist for many of the monitored analytes, computation of accurate pollutant loads requires frequent sampling during major runoff events. In addition, shifts in concentration/flow relationships can occur between storms and across the monitoring season, requiring intensive sampling of all major runoff events. Low-flow periods are also sampled and are well represented, but sampling frequency tends to be less as concentrations are generally more stable when compared to periods of elevated flow. Despite discharge-related differences in sample collection frequency, this staggered approach to sampling generally results in samples being well distributed over the entire range of flows.
Example: Lac qui Parle River hydrograph with sample collection dates plotted
For detailed procedural information, see the 
Major Watershed Load Monitoring Standard Operating Procedure (wq-cm1-02).
In-field measurements
|
pH |
pH is a measure of acidity and alkalinity of a solution on a scale of 0 to 14, where 7 is neutral and lower numbers represent acidity and higher numbers represent alkalinity; the optimal range for most organisms is 6.5 to 8.2. Dissolved oxygen (DO) is indirectly affected by changes in pH. The toxicity of many compounds can be altered if pH changes, because pH alters chemical and biological reactions and processes. Changes in pH are predominantly related to the health of aquatic organisms, especially fish and invertebrates. |
|---|---|
|
Temperature |
Temperature is a measure of warmth or coldness of a substance with reference to a standard value (USGS). Temperature affects many physical, biological and chemical characteristics such as dissolved oxygen, rate of photosynthesis, metabolic rates and sensitivity to toxics, parasites and disease |
|
Conductivity |
Conductivity is a measure of the ability of water to pass an electrical current. Conductivity in water is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge). Conductivity is affected by temperature: the warmer the water, the higher the conductivity. For this reason, conductivity is reported as conductivity at 25 degrees Celsius (25 C). Conductivity is useful as a general measure of stream water quality. Each stream tends to have a relatively constant range of conductivity that, once established, can be used as a baseline for comparison with regular conductivity measurements. Significant changes in conductivity could then be an indicator that a discharge or some other source of pollution has entered a stream (USEPA). |
|
Dissolved oxygen |
Dissolved oxygen is a measure of the amount of gaseous oxygen (O2) dissolved in water. Oxygen gets into water by diffusion from the surrounding air, aeration (rapid movement of water), and as a waste product of photosynthesis. Adequate dissolved oxygen is necessary for good water quality and oxygen is a necessary element to all forms of life. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. |
|
Turbidity |
Turbidity is the measurement of scattered light that results from the interaction between a beam of light and particulate material in a liquid sample. It is an expression of the optical properties of a sample that causes these light rays to be scattered and absorbed rather than transmitted in straight lines through the sample1. Turbidity of water is often caused by the presence of suspended and dissolved matter such as clay, silt, finely divided organic matter, plankton, other microscopic organisms, organic acids, and dyes. Turbidity has been used as a key indicator for water quality to assess the health and quality of environmental water sources. Higher turbidity values are typically associated with poorer water quality. |
|
Transparency tube |
A transparency tube reading is an indirect measure of the amount of dissolved and suspended material present in the water, transparency tells us when key water pollutants are present |
Laboratory samples
|
Total suspended solids (TSS) |
Total Suspended Solids (TSS) are solids in water that can be trapped by a filter. TSS can include a wide variety of material, such as inorganic sediments like silt and clay and organic material like decaying plant and animal matter. High concentrations of suspended solids can cause many problems for stream health and aquatic life. The decrease in water clarity caused by TSS can affect the ability of fish to see and catch food. Suspended sediment can also clog fish gills, reduce growth rates, decrease resistance to disease, and prevent egg and larval development. When suspended solids settle to the bottom of a water body, they can smother the eggs of fish and aquatic insects, as well as suffocate newly hatched insect larvae. Settling sediments can fill in spaces between rocks which could have been used by aquatic organisms for homes. 2 |
|---|---|
|
Suspended volatile solids (SVS |
Suspended Volatile Solids is a measure of the amount of total suspended solids that are lost on ignition (heating to 550 degree C). This measure is often used to determine the proportion of TSS composed of organic matter. |
|
Turbidity |
See “In-Field” definition of turbidity. |
|
Dissolved orthophosphate (DOP) |
Dissolved orthophosphate is a measure of the filterable (soluble, inorganic) fraction of phosphorus, the form directly taken up by plant cells. |
|
Total phosphorus (TP) |
Phosphorus exists in water in either a particulate phase or a dissolved phase. Particulate matter includes living and dead plankton, precipitates of phosphorus, phosphorus adsorbed to particulates, and amorphous phosphorus. The dissolved phase includes inorganic phosphorus and organic phosphorus. Total phosphorus (TP) is a measure of all the forms of phosphorus, dissolved or particulate, found in a sample. Phosphorus is a nutrient required by all organisms for the basic processes of life. Phosphorus is a natural element found in rocks, soils and organic material. Phosphorus clings tightly to soil particles and is used by plants, so its concentrations in clean waters are generally very low. In freshwater lakes and rivers, phosphorus is often found to be the growth-limiting nutrient, because it occurs in the least amount relative to the needs of plants. If excessive amounts of phosphorus are added to the water, algae and aquatic plants can be produced in large quantities. When these algae die, bacteria decompose them, and use up oxygen.2 |
|
Nitrate plus nitrite nitrogen (NO3+NO2) |
Nitrate (NO3) is highly soluble (dissolves easily) in water and is stable over a wide range of environmental conditions. It is easily transported in streams and groundwater. Nitrates feed plankton (microscopic plants and animals that live in water), aquatic plants, and algae, which are then eaten by fish. Nitrite (NO2) is relatively short-lived in water because it is quickly converted to nitrate by bacteria. Nitrogen is required by all organisms for the basic processes of life to make proteins, to grow, and to reproduce. Nitrogen is very common and found in many forms in the environment. Inorganic forms include nitrate (NO3), nitrite (NO2), ammonia (NH3), and nitrogen gas (N2). Excessive concentrations of nitrate and/or nitrite can be harmful to humans and wildlife.2 |
|
Total Kjeldahl (TKN) |
The measure of the sum of organic nitrogen, ammonia and ammonium: used in the calculation of total nitrogen. Ammonia, is an inorganic form of nitrogen and is the least stable form of nitrogen in water. Ammonia is easily transformed to nitrate in waters that contain oxygen and can be transformed to nitrogen gas in waters that are low in oxygen. Ammonia is found in water in two forms - the ammonium ion (NH4+), and dissolved, unionized (no electrical charge) ammonia gas (NH3). (NH3) is much more toxic to aquatic organisms than the ammonium ion (NH4+). When plants and animals die, organic nitrogen contained within is broken down by bacteria to form ammonia (NH3). |
|
Total nitrogen |
The sum of nitrate plus nitrate nitrogen and total kjeldahl nitrogen. Total nitrogen is the measure of all organic and inorganic forms of nitrogen contained within a water quality sample. |
References:
- S. Clesceri, L. Greenberg, A and Eater 1998. “Method 2130. Turbidity”, Standard Methods for the Examination of Water and Wastewater, 20th Ed. , American Public Health Association, Washington DC.
- Murphy, Shelia, 2007. Boulder Area Sustainability Information Network. http://bcn.boulder.co.us/basin/data/NEW/info/index.html
Analytical procedures
A pollutant load is the amount of a pollutant passing a specific stream location over a period of time. For the MWLMP pollutant loads are calculated by collecting water quality samples at USGS or DNR flow gaging locations over the full range of flow volumes. Annual water quality and daily average discharge data are used in the “Flux32,” pollutant load model, originally developed by Dr. Bill Walker and recently upgraded by the USACE/MPCA, to create concentration/flow regression equations to estimate pollutant concentrations and loads on days when samples were not collected. Primary output includes annual and daily pollutant loads and flow weighted mean concentrations (pollutant load/total flow volume). Pollutant loads and flow weighted mean concentrations are calculated for total suspended solids (TSS), total phosphorus (TP), dissolved orthophosphate (DOP), nitrate plus nitrite nitrogen (nitrate-N) and total kjeldahl nitrogen (TKN).
How are pollutant loads calculated?
Monitoring and load calculations for the MWLMP are conducted on a calendar year basis from January 1st through December 31st. Daily pollutant loads are calculated by multiplying daily average flow times the actual or estimated daily pollutant concentration. Annual loads are the sum of daily loads across the calendar year.
Contacts/Links
Contact information
Contact the monitoring staff in your region to answer your questions or for more information about the Major Watershed Load Monitoring Program.
|
Supervisor |
Stephen Thompson, 651-757-2778 |
|---|---|
|
Monitoring Coordinator |
Pat Baskfield, 507-344-5240 |
|
Metropolitan Council |
Karen Jensen, 651-602-1000 |
|
Central Minnesota |
Jim MacArthur, 218-316-3881 |
|
East Central Minnesota |
Gerry Flom, 651-757-2363 |
|
Northwestern Minnesota |
Andy Butzer, 218-846-0485 |
|
Northeastern Minnesota |
Stacia Grayson, 218-302-6631 |
|
Southwestern Minnesota |
Anthony Dingman, 507-476-4253 |
|
Southeastern Minnesota |
Mike Walerak, 507-206-2623 |
Who collects data
- MPCA Major Watershed Load Monitoring Staff
- Metropolitan Council Environmental Services
- Local groups:
Links to related information
Flux32 Software
Flux32 Software
Flux32 is windows based interactive software developed by Dave Soballe, US Army Corps of Engineers, in conjunction with the Minnesota Pollution Control Agency. Flux32 is based on the original FLUX application written by William Walker, Ph.D., under sponsorship of the U.S. Army Corps of Engineers (USACE) in the 1980s as a DOS-based program for personal computers. Flux32 is user friendly and capable of sophisticated examinations and evaluations of data and flow relations and calculation of material fluxes (loads) in streams.
FLUX32_20110829.zipTo be added to the mailing list for notification of new releases or to report problems running Flux32, please email stacia.grayson@state.mn.us.