Study: Manure Bigger Problem For Lake Erie Algae Than Previously Thought

Aerial view of a pig farm surrounded by wheat fields. [Kletr / Shutterstock]
Aerial view of a pig farm surrounded by wheat fields. [Kletr / Shutterstock]
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One of the conundrums in the effort to halt toxic algal blooms in western Lake Erie, near Toledo, is why phosphorus levels continue to rise, even though farmers in the Maumee River watershed have been using less fertilizer. Two environmental groups think manure is playing a larger role than researchers have previously thought. 

The Environmental Working Group in Washington, D.C. and the Environmental Law and Policy Center in Chicago say they found factory farms have grown by 40 percent since 2005, and more than half the manure they generate is coming from operations that don’t require permits or manure management plans.

Sarah Porter, a senior geospatial analyst with the Environmental Working Group, addressed some of the criticisms of the study including agriculture groups that questioned the data.

Researchers have focused on commercial fertilizer, which you estimate in your report as accounting for 80 percent, and manure at 20 percent. How has your study added to what we know about this breakdown, and why is it important to pinpoint whether agricultural runoff is fertilizer or manure?

What we looked at in our study was to use aerial photography and satellite imagery to map where those animal feeding operations are, and we found several hundred more than what would be known when looking at the available permit data. It’s important to understand where that phosphorous is coming from, whether commercial fertilizer or manure, so you can better develop management plans to address the problem specific to that source.

These smaller farms aren’t breaking laws. The state allows them to operate without a manure management plan, specifically because of their smaller size.

Correct, but the problem arises when you have many of these operations clustered together, along with these larger facilities. What you wind up with is a lot of manure being generated in one place, which can be costly to transport to fields. The further away you need to transport it, the cost goes up. The worry is that, because of this cost, manure might be applied to fields at rates higher than what the land can handle.

There was a lot of estimating in your report. The Ohio Farm Bureau called your data “iffy.”

There’s a number of characteristics about these barns that make them easy to identify from aerial photography. These are modern facilities; they use modern technology to construct them. There’s characteristics unique to poultry barns versus swine barns. You can’t dispute the fact that we found 230 operations that were added to the landscape in that time period. We don’t think that we should have to be mapping these in the first place. The state should know where these things are.

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