Broken Stream Banks
Failure to maintain buffer zones worsens farm pollution
Broken Stream Banks
Broken Stream Banks
Failure to maintain buffer zones worsens farm pollution
Water pollution from farmland is a major problem in southern Minnesota and wherever row crops dominate the landscape across the United States. Much of this pollution can be prevented by the conscientious use of riparian buffers – strips of grass, trees or other permanent vegetation maintained along the banks of rivers, streams, lakes and other waterways.
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Minnesota is a national leader in recognizing the importance of these buffers in combatting agricultural pollution. The state’s Shoreland Management Act confers legal protection of riparian buffers between most waterways and farmland. Like any other law, however, it must be enforced to be effective.
In 2013, the Environmental Working Group used high-resolution aerial photography to assess how well the law is working and to help county and state officials in their efforts ensure the required buffers are maintained between row crops and public waterways.
This report and the interactive maps show what EWG found.
Only 18% of perennial river and stream banks in agricultural areas are fully protected.
| Grade | Percent of Required Buffer Present | Missing Buffer Acres | Number of Waterways | Percent of Waterways |
|---|---|---|---|---|
| A | 100% | 0 | 87 | 18% |
| A- | 99-90% | 59.4 | 57 | 12% |
| B | 89-80% | 235.3 | 81 | 17% |
| C | 79-70% | 626.1 | 93 | 19% |
| D | 69-60% | 673.7 | 66 | 14% |
| F | 59-0% | 690.5 | 101 | 21% |
| Total | 2,285 | 485 | 100% |
While sizeable numbers of landowners maintain the required 50-foot riparian buffers, many others do not. Buffers are often far narrower than required and in some cases are completely missing. Overall, about 72 percent of the required buffering acres were in place in agricultural areas. But the overall average is misleading, because there are large differences among waterways. Only 18 percent (87 waterways) earned an A, meaning 100 percent of the required buffer was maintained along the waterway. In contrast, 21 percent (101 waterways) got a failing grade – less than 60 percent of the buffer acreage was in place.
Waterways that earn top grades are frequently next door to areas with failing grades.
A-Grade
The wide-strip of vegetation along this stream filters out pollutants and keeps the stream bank from collapsing. Runoff and broken banks are a major source of pollution in southern Minnesota waterways.
