MWMO Interns Christi Wahlstrom, Melissa Burton and Anna Johnson collect macroinvertebrate samples from one of the Kasota Ponds. (Credit: MWMO)
One organization in Minnesota is keeping a close eye on the northern part of the Mississippi River through an extensive water quality monitoring effort that includes the river, a stormwater drainage system, and local lakes and wetlands.
The Mississippi Watershed Management Organization — also known as the MWMO, a special purpose local unit of government in Minneapolis, Minnesota — is responsible for monitoring the water quality of the 14-mile stretch of the Mississippi River that runs through Minneapolis and St. Paul.
Starting at Lake Itasca in Minnesota, the Mississippi River flows south for 2,230 miles, bordering or passing through 10 states until it flows into the Gulf of Mexico. It provides a home for many species of fish, mussels, amphibians and reptiles, as well as a flyway for many species of birds during migration. Additionally, the river provides drinking water for at least 50 cities, according to the U.S. Environmental Protection Agency.
It’s no secret that the water quality from the river is a main contributor to the large dead zone in the Gulf every year.
All of this makes monitoring the river’s water quality a necessity and MWMO, a small but robust organization, is dedicated to being a steward for their designated 14 miles of the Mississippi River.
“Our stretch of the river includes a water intake for the City of Minneapolis drinking water supply and it is also designated for recreation activities like fishing and swimming,” said Udai B. Singh, the organization’s water resources director who has a Ph.D. in civil and environmental engineering.
Other agencies have monitored the 14-mile stretch of the Mississippi River at a few locations. The MWMO began tracking the river at six monitoring sites in 2015 and added two more monitoring sites in 2016. The MWMO is currently focusing on building baseline data.
“Prior to 2015, we gathered three years of water temperature, pH, dissolved oxygen, and conductivity data at multiple depths at six monitoring locations. This monitoring was conducted to determine whether the river within our stretch becomes stratified at any point during the year or remains hydraulically mixed from top to bottom,” said Singh. “In 2015, we began collecting samples for water quality analysis. We want to establish a 10-year baseline of data, so we aren’t drawing conclusions from the data right now.”
With a staff of only 15 full-time employees, which includes five environmental scientists, the organization performs bacteria and water quality monitoring in its stretch of the river, as well as water quantity and water quality monitoring in the stormwater drainage system of the watershed. Bacteria monitoring is done every second and fourth Thursday of each month, regardless of the weather. To collect water samples, the specialists plunge a sample bottle one foot below the water’s surface. The samples are analyzed in a laboratory for E.Coli.
“During rain events the E.Coli levels are typically higher,” said Singh. “We recommend that residents avoid recreation activities in the river for three days after a rain event.”
The results of the bacteria monitoring showed that during the months of August and September in 2016 at least four sites exceeded the acceptable standard for E. coli presence in the water.
Water quality monitoring is done from the organization’s 14-foot john boat. The team uses horizontal water sampler (also known as a Van Dorn sampler) to grab water samples from the middle of the river as long as weather permits. During the colder months the samples are taken from the shore or by lowering the sampler from a bridge. The samples are analyzed in a laboratory for, nutrients, sediment, chloride, heavy metals, biochemical oxygen demand (BOD), and Chlorophyll-a.
They also use handheld YSI ProPlus sondes to collect dissolved oxygen, conductivity, salinity, water temperature and pH value measurements.
In addition to monitoring the river itself, the MWMO pays attention to the watershed as a whole.
“We want to know the condition of the water before it reaches the river,” said Singh.
To capture that data, the organization focuses on the local stormwater drainage systems and developed an extensive monitoring plan that includes six stormwater outfalls into the river and one stormwater pipe. The quality of the water in the stormwater drainage systems is affected by the land uses of the area surrounding it. In the MWMO watershed the surrounding areas include residential, commercial, and industrial developments. When it rains, all of the surface debris and pollution is transported into the stormwater drainage systems and eventually into the river.
The data could potentially show which areas are carrying more pollution into the river and provide a starting location for mitigation efforts.
The organization monitors water quality and quantity. To ascertain the water quantity, each site is equipped with an area/velocity sensor that is connected to an area/velocity flow module. The sensor and flow module provide water level and velocity data. When coupled with the area dimensions of each pipe, MWMO is able to use this data to figure out the discharge from the stormwater pipe.
Water quality monitoring is conducted with Isco 6712 automatic samplers. These pre-programmed samplers include twenty-four one-liter plastic bottles for composite sample collection and are connected to the area velocity flow module. When the water level reaches a certain value above baseflow, the sampler starts sampling. More bottles are filled as a preset volume of water passes the sensor.
Once collected, the bottles are composited by a monitoring specialist by pouring an equal amount of water from each sampler bottle into a plastic bottle. The combined sample is taken to a laboratory for analyses similar to the samples taken directly from the river.
Stormwater monitoring also includes the use of an YSI ProPlus sonde and a Secchi tube to measure the transparency of the water.
Although the organization isn’t currently drawing conclusions from the data, it is available to the public upon request and will be made available via the MWMO’s website in future. While the main focus of the water monitoring efforts is currently on gathering enough baseline data to draw conclusions and make water management decisions in the near future, the time on the river is valuable for the staff and the community.
“From being on the river so much, we are able to act as eyes and the ears for the river,” said Singh.
The community recognizes the work that MWMO is doing. In the past, members of the organization were called in during crisis situations, such as the I-35W bridge collapse that killed 13 people in 2007.
“When that happened members of our team were called to monitor any effect on the river,” said Singh.
The MWMO is also a partner of the City of Minneapolis in the Illicit Discharge Prevention Program. MWMO’s participation in that initiative helps alert the city to any illicit discharge to the river.
The organization’s work doesn’t stop with water quality monitoring. In addition to those efforts, MWMO funds capital grant projects that are large-scale stormwater management projects or improve the habitat and water quality within their watershed. Education and outreach is also a big component of their work. MWMO’s headquarters (also called the Stormwater Park and Learning Center) provides a green infrastructure learning experience and other education initiatives.
“We have come a long way. We started with a team of two staff in 2002 to a fifteen member team now. We put a comprehensive watershed plan in place, and do monitoring and water quality projects. We continue to work with the public with education and outreach,” said Singh. “Our organization is now positioned to be a champion of and advocate for the river.”