When snow melts or rain falls, the water picks up pollutants as it drains across land to a stream. Measuring that flush of pollutants can be tricky because some stream water levels rise and fall so quickly – in a matter of hours. It’s also important because the bulk of pollutants can come from one major storm in a season.
Seeking to detect that flush of pollutants, staff from the Zumbro Watershed Partnership is heading out into the elements this year to check the river for pollutants when snow begins to melt or rain starts to fall. These checks include measuring the water temperature, its clarity and other conditions.
Staff will also take water samples for lab analysis to determine levels of nutrients and sediment. These are the two most common pollutants in Minnesota waters, with nutrients fueling algal blooms and sediment clouding the water.
While the Zumbro Watershed staff and local partners regularly monitors the health of the Zumbro River and it's tributaries, this water monitoring is special because it captures the level of pollutants in runoff. Water picks up soil, fertilizer and other pollutants as it runs off the land to a stream, lake or wetland.
“Pollutant loads are typically highest during and after high precipitation events because many pollutant concentrations are often highest during periods of elevated stream flow. Concentrations can also vary between events as the source of runoff and contributing pollutant sources differ with rainfall intensity, areas of bare soil, and other factors,” said Pat Baskfield, hydrologist with the Minnesota Pollution Control Agency (MPCA) groundwater and load monitoring unit.
“Capturing data from all major events during first flush and the ensuing high flow period is essential to determining the health of rivers across Minnesota. Each bit of data helps to fill in a picture of water quality,” he said.
To accurately determine a pollutant load, the Zumbro watershed staff will also check the river during typical flow conditions – when no rain or snowmelt occurs – to establish a baseline of pollutant levels. These checks will provide a comparison point to determine the amount of pollutants flushed in during high water periods.
The data from Zumbro watershed will flow into a statewide water monitoring network, along with six other groups in southern Minnesota. The MPCA recently awarded more than $900,000 in grants to these local partners to do this monitoring. The Zumbro Watershed Partnership received some of that funding to help pay for staff time, lab analysis, and equipment for monitoring four sites on the Zumbro River.
These points of data will provide long-term information to help fill in the picture of water quality across the state. The Zumbro staff will combine these water quality data with stream flow information to estimate overall pollutant loading from a watershed or drainage area.
This effort is part of agency-led Watershed Pollutant Load Monitoring Network, which collects data to provide information about the health of Minnesota watersheds – our rivers and what feeds into them. The information helps identify where excessive pollutants are entering river systems, from both direct and runoff sources.
Because this network is statewide and long-term, it can help identify trends over time and compare one part of the state to another. It is also useful to evaluate the effectiveness of remedial activities and to identify waters that need protection.
For more information visit the network’s website (http://www.pca.state.mn.us/index.php/water/water-types-and-programs/surface-water/streams-and-rivers/watershed-pollutant-load-monitoring-network.html).
For the recent funding round, the MPCA also awarded grants to:
· Cannon River Watershed Partnership;
· Chippewa River Watershed Project;
· Fillmore Soil and Water Conservation District;
· Hawk Creek Watershed Project;
· Minnesota State University-Mankato Water Resources Center; and
· Redwood Cottonwood Rivers Control Area.
These grants are funded by the Clean Water, Land and Legacy Amendment. The next funding round for this program will be in August 2013 and target northwestern, north-central, and northeastern Minnesota.
Source: Zumbro Watershed Partnership and the MPCA