As rainy spring weather washes phosphorus off farmfields, in northwest Ohio鈥檚 Defiance County are working to catch the nutrient 鈥� before it gets into the streams and waterways that feed Lake Erie.
The project is part of a broader effort to prevent harmful algal blooms there.
鈥淚f we can just get to, say, 20% of the high phosphorus fields, that will be a big success and will have a big impact on removing the phosphorus that gets into Lake Erie,鈥� said Matt Fisher, vice president of the .
The nonprofit has installed five filters in the past couple of months and is monitoring their effectiveness.
How do the filters work?
The phosphorus filters work like giant sieves, Fisher said.
They鈥檙e about 20 by 30 feet wide and around 12 feet deep, depending on the size of the area they serve.
鈥淭he fields drain into those filters on one side, flow through a series of pipes and media, and exit with what has turned out so far to be very clean water,鈥� Fisher said.
About a month in, he says the filters are removing nearly all of the dissolved reactive phosphorus from the farm runoff they鈥檙e collecting.
What makes the filters a useful tool?
There鈥檚 been a big push in recent years to teach farmers about nutrient application and employ .
Those are helpful strategies, Fisher says, but these new phosphorus filters are useful for capturing phosphorus in 鈥渓egacy fields鈥� where the nutrient has been accumulating over many decades.
鈥淎bout 9% of the fields are responsible for 35%-plus of what runs off into the Maumee,鈥� Fisher said. 鈥淪o we want to find as many of those 9% as we can, and try to work with leaders of the agriculture community to put filters in those places to try to catch as much dissolved reactive phosphorus as we can.鈥�
The filters are expensive: Fisher says each one costs about $10,000.
But because they should last for about a decade and cover large areas, Fisher finds the solution encouraging.
He鈥檚 hopeful more will be added across the region, and that they鈥檒l work to help keep Lake Erie clean.