Conservation Minnesota

Will Buffers Clean Our Lakes?

As a lake manager and scientist, I want to comment on buffers’ benefits for lake quality.

There is a great deal of rhetoric and hype surrounding the buffer bills circulating in the legislature.  As an aquatic scientist, I get frustrated when both sides of the same issue plea for science-based approaches, but then cherry-pick tidbits from scientific literature.  In addition, much of the critical information is glossed over and squeezed into sound bites making it appear that all our waters will become sparkling clean.

As well, many news releases include lakes, explicitly or by implication, among the beneficiaries of the buffer proposal.

These practices are misleading, unfortunate and unnecessary.  Streams and groundwater will benefit from buffers, but not lakes.

Recently the Minnesota Center for Environmental Advocacy (MCEA) released a fact sheet titled, “The Benefits of Buffers: What the Science Has to Say” under the banner “#BuffersNow Coalition Partners.”  The document cites several scientific studies supporting buffers’ value.  I have read all of these studies relative to buffers’ ability to mitigate phosphorus, a critical pollutant causing lake impairments.

According to these studies, the evidence for buffers’ benefits to remove phosphorus is lacking, insufficient and incomplete.

Not all of the studies evaluated phosphorus.  Those that did, were limited in scope.  For example, no studies evaluated buffers during periods when there was no vegetation, such as in the springtime before plants have emerged.  One study only evaluated a single sampling date, one study evaluated artificial buffers representing “ideal” conditions, one study evaluated other studies and did not include any quantitative results, one study citied another study that found “insufficient evidence to determine buffer width for phosphorus retention.”  One study says, “At this time, research reports are lacking that quantify a change in pollutant levels (concentration and/or load) in streams or lakes in response to installation of buffers. ”  Interestingly, the MCEA fact sheet summarizing the same study says, “Abundant evidence clearly indicates that buffers retain pollutants from surface runoff from fields … ”

Lacking demonstrable efficacy of buffers’ to mitigate phosphorus as well as the fact that lakeshores are specifically excluded in the buffer bills, it is unlikely any significant improvement to lakes from reduced phosphorus will be forthcoming from this program.

That said, buffers are beneficial for streams and groundwater and I support the concept.

It is clear from scientific studies that vegetated buffers are beneficial for mitigating the impacts of some polluted runoff.  What is not clear however, are the particulars.  The “one-size-fits-all” argument is valid to the extent that for buffers to effectively moderate pollution, they must be properly designed, sited, maintained as well as implemented in conjunction with other conservation practices.  But let’s not let this stop progress.  Fifty-foot vegetated buffers are easy to monitor and regulate.  And buffers along flowing waters will reduce water pollution and provide wildlife habitat in most cases.

We need more than buffers for impaired lakes, so other initiatives will be required.

But for other polluted waters, this proposal is a good start.

About Dick Osgood

Dick Osgood
Dick Osgood has authored numerous scientific journal papers, made hundreds of presentations at professional meetings, and recently co-authored his first book.  Now he’s working on his second book titled A Lake Manager’s Notebook.  Dick is a Certified Lake Manager and offers lake management consulting services through his business Osgood Consulting LLC.
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