Stephanie Hemphill: Farmers Reducing Phosphorus Runoff

ENSIA:

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Why exactly does Green Bay need saving? Because it suffers from too much phosphorus, which contributes to Cyanobacteria, more commonly known as blue-green algae. Around the world, these bacteria are turning water a disgusting shade of green and other colors, and producing poisons that can sicken people and kill animals. And when the algae die off they can rob oxygen from other life in the water, killing fish and other aquatic life.

Around Green Bay, several small streams carry excess nutrients from farm fields into the bay and eventually into Lake Michigan. One of them, Silver Creek, is the focus of a pilot project designed to answer a crucial question: Can farmers reduce their pollution enough to help the bay, while remaining profitable? The project lies within the boundaries of the Oneida reservation, and more than half the land is owned by the tribe, which leases a lot of land to non-tribal growers...

Five years in a pilot program isn’t much time to clean up a stream, but the ultimate goal of adaptive management is to bring Silver Creek up to the state’s water quality standard for phosphorus. NEW Water says the project has cost US$1 million dollars annually over the last four years. That’s a lot cheaper than US$100 million for a new treatment plant. And how well is it all working?

The project promises to provide extensive data about how well various agricultural practices work to reduce polluted farm runoff. The weekly samples from five monitors along Silver Creek provide baseline measurements from the year before the BMPs started. This is not as precise as more expensive continuous monitoring would be, but it offers more experimental rigor than most studies can provide.

Those five monitors continue to track water quality. So far, the results are mixed. In 2016, three of the monitors showed phosphorus reductions, one stayed essentially the same and one showed a slight increase. In 2017 the area was drenched with what felt like endless rainfall, soaking the fields and making them more vulnerable to runoff. The phosphorus numbers went up, but not to levels seen pre-BMPs. “I was very happy to see that even with a very wet year we never even approached the concentrations we saw before we started installing these best management practices,” NEW Water’s Erin Houghton says.