It will be 20-30 years before we start seeing improvements in the polluted lakes and streams in southwest, southeast and central parts of Minnesota, a new report says.
Minnesota's Pollution Control Agency released the findings from the first half of its 10-year study into water quality in the state on Wednesday.
Water quality has come into sharp focus after recent reports on the shocking condition of lakes, rivers and streams in heavily farmed parts of the state, which has rendered many unfit for recreational use.
So far, MPCA officers have studied half of the 81 watersheds in Minnesota (areas of land where all the water drains to the same place). Among the key findings:
- Excess phosphorous levels (which causes algae) in watersheds where the surrounding land is agricultural or urban has resulted in at least half of lakes failing to meet the standard for swimming.
- Watersheds that are heavily farmed tend to have high level of nitrogen, phosphorous and small solids which hurt aquatic life and recreational opportunities.
- Areas with high human or livestock population are leading to high bacterial pollution (such as E.coli) in more than half of streams.
- 97 percent of stream sections examined, and 95 percent of 1,214 lakes studied, contain fish tainted by mercury.
- Forest/wetland areas in north-central and northern Minnesota have the best quality water.
Phosphorous pollution makes the case for 'buffers'
Phosphorous was found to be the main pollutant of Minnesota's lakes, with high levels caused by runoff from farmland causing algae to grow – and in the most extreme cases, reaching levels that release toxins harmful to people and pets.
Gov. Mark Dayton was joined by the MPCA as the report was presented on Wednesday morning. Dayton is backing a proposal to create 50-foot "buffers" of vegetation on farmland next to waterways, which environmental officers say will go some way to reducing the pollution.
But it faces a level of opposition from the agricultural industry.
Another issue was excess sediment, particles of soil and other matter, in the state's rivers and streams, which cause clouding, making it hard for fish to breathe and reproduce.
Attendees at the press conference were shown a contrast between the sediment-heavy Mississippi where it is joined by the cleaner St. Croix River at Prescott.
How to improve MN waters
The MPCA says that restoring water quality to Minnesota's lakes, rivers and streams is a long-term process, taking at least 20 to 30 years before a discernible impact can be seen.
It calls for stream buffers and manure management on agricultural land to reduce pollution caused by chemical runoff from fertilizers, as well as the restoration of some wetlands.
In urban areas, it wants improvements to the way cities deal with stormwater runoff, by encouraging the building of rain gardens as well as stormwater ponds and wetlands.
And while it is not necessarily related to water quality, the MPCA says more work needs to be done to improve the habitats and reducing the barriers for the state's fish and other aquatic life.
"It took decades to pollute lakes and streams," the report says, "And it will take many years to restore impaired waters while working to protect healthy waters as new threats emerge."