Mississippi River starts clean, heavily polluted as it runs south
The Mississippi River starts at Lake Itasca clear and clean, and pretty much stays that way as it winds through northern Minnesota's forests and wetlands. But by the time the river flows into the Twin Cities it's been polluted so badly that it fa...
The Mississippi River starts at Lake Itasca clear and clean, and pretty much stays that way as it winds through northern Minnesota's forests and wetlands.
But by the time the river flows into the Twin Cities it's been polluted so badly that it fails federal Clean Water Act standards for aquatic life and human use.
The Minnesota Pollution Control Agency today released a report outlining what is fouling the water - namely runoff from farms and pollution from cities - and what can be done to solve the problem.
The solutions include protecting northern Minnesota forests and wetlands that filter water that flows into the river in its upper stretches as well as curbing agricultural and urban runoff that carries sediment and toxic chemicals.
"The forested and wetland-rich character of the northern portion of the basin ... must be kept as intact as possible," the report notes.
The report also notes that it's critical to make sure city sewage treatment plants and rural residential septic systems are working properly.
The river is in good shape as it meanders through lakes Bemidji and Winnibigoshish and on through Grand Rapids. But south of Grand Rapids, sedimentation becomes a problem. By the time the rivers flows south of Brainerd and St. Cloud, bacteria levels shoot up and "pollutants start to pour in with runoff, drainage and tributaries. These pollutants include sediment that clouds the water; nutrients that cause algal blooms; and bacteria that can make the water unsafe for swimming," the PCA report notes.
"What we do on the land is reflected in the water," said John Linc Stine, PCA commissioner, in a statement. "This study underscores that point."
While it's imperative that the flow of pollutants into the river in central Minnesota is halted, it's also critical to protect the northern headwaters area that helps produce clean water to start, Stine said. But efforts to fell forests and open land to more crops in some counties, as well as other development in the north, threaten those buffering abilities.
"Whenever land goes from a stable and vegetated state without protections in place, water quality will go down. That's the lesson of history," Stine said.
For northern Minnesota, the study says major threats to the Mississippi River watershed include:
- Loss of shoreline and aquatic habitat due to development. Many of the prime lakeshore properties have been developed with the focus now turning toward more marginal shoreland and/or shoreland along sensitive, smaller natural lakes, ponds and streams.
- Increased sedimentation due to forest management practices.
- Increased nutrient, contaminant and sedimentation loading from stormwater runoff from development and other non-point sources.
- Loss of biodiversity due to competition from invasive species.
The PCA looked at 510 miles of the upper Mississippi River from Lake Itasca to St. Anthony Falls in Minneapolis. Scientists measured levels of pollutants such as sediment, nutrients, bacteria and mercury. They also studied populations of fish and other aquatic life such as insects. Researchers used data collected at nearly 200 monitoring stations along the river.
The river is important not just because of its recreational and aesthetic qualities for Minnesota and the nation's Heartland, but also because of its impact on everyday human life.
"It's hard to overstate the river's importance as a drinking water source to millions of Minnesotans and (other) Americans downstream," the PCA said in releasing the report.
Lower reaches need "large-scale changes to reduce pollutants," the report notes.
After the Crow River flows into the Mississippi, phosphorus and nitrate pollution doubles. The Crow River drains a large area that's heavily farmed.
"Thanks to groups like the Crow River Organization of Water, watershed districts, and soil and water conservation districts, work has already started to curb this pollution. But we all need to do more. We need more buffers, better use of fertilizer and manure, and more conservation on farmland and urban land," said Dana Vanderbosch, manager of lake and stream monitoring for the PCA.
Toxic mercury levels in fish, spurred by airborne mercury that comes from both local and global sources and falls in rain and snow, is high throughout the river, making large fish unsafe for women and children to eat on a regular basis.
The report can be seen at pca.state.mn.us/upper-m .