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Public Radio's Environmental News Magazine (follow us on Google News)

Cow Waste and Artifical Wetlands

Air Date: Week of

Lorna Jordan of member station WVXU reports on artificial wetland used to clean up agricultural runoff in LaGrange County, Indiana. Animal waste can contaminate water sources, but by first sending it through constructed wetlands, about forty percent of phosphates and nitrites on this farm are safely filtered out.


CURWOOD: This is Living on Earth, I'm Steve Curwood.

When one thinks of farming, it's not hard to conjure up a bucolic image, complete with fresh air, green fields and bountiful crops. So the notion that farming is a major cause of pollution can be jarring. But in fact some farming methods do dump significant amounts of pollutants into the ground and waterways. Some comes from pesticides, but a good deal comes from animal wastes, loaded at times with dangerous bacteria. Agricultural runoff is at the top of the list of reforms as Congress considers reauthorizing the Clean Water Act. In LaGrange County, Indiana, a group of researchers has responded to the challenge with an experimental natural treatment system which they hope will catch on with farmers around the country. Lorna Jordan of member station WVXU has our report.

JORDAN: The 100 head of Jersey cattle on Rodney Taylor's Norwood Farms in LaGrange County, Indiana, produce 140 hundred gallons of milk every day. The cows also produce something else - politely called animal runoff. The residue used to flow through a four-foot gully which drained into Appleman Lake on the edge of the farm. But now, three tiny wetlands lie between the barn and the lake. Farmer Rodney Taylor says the wetland may look like an ordinary gully, but it's cleaning the water flowing into Appleman Lake.

TAYLOR: It's doing the job. It is working. You know, the water that goes through there, which is rather yucky looking, ends up as pretty decent water going into the pond.

JORDAN: Wetlands like this could be one of the solutions to the growing threat of farm pollution. This farm was chosen, in part, because of the high levels of nitrates and phosphates found in the lake. Runoff from this farm is probably the cause of that pollution, and in time it produces so much plant growth that the lake would choke.

DUBOWY: In many places agricultural runoff is one of the principle factors contributing to pollution of surface and groundwater.

JORDAN: Dr. Paul DuBowy is a professor of wildlife ecology at Purdue University. He designed this wetland.

DUBOWY: What you're seeing in these constructed wetlands really isn't very different from your typical sewage treatment plant. The same biological processes that happen in a municipal plant are the same ones that are happening right here.

JORDAN: DuBowy says the wetlands clean the water with specially-picked plants. First the manure settles in a cement holding pond. Then the contaminated water is pumped into the wetlands, where the plants convert the nitrates and nitrites into food and allow the nitrogen gas to escape into the air. Most of the phosphorus settles onto the bottom of the ditch or adheres to the plants. Finally the cleaned water is released into the lake at the other end of the wetlands. DuBowy says tests have shown that this wetland reduces the amount of phosphates and nitrites by about 40%. Russell Baker is the District Water Conservationist in LaGrange County.

BAKER: One of the reasons we's looking at this wetland is we are looking at alternative facilities, or alternative treatment facilities. So many of our facilities now are things where they'll store the manure but you still have to deal with it later. Whereas this here, you got the runoff, it goes through the wetland cells, hopefully gets treated, and then you can just discharge it. You don't have to worry about it again. Now, you still may have to worry about the solids, but his certainly could help.

JORDAN: In a wetland system like the one on Norwood Farms, the solid animal waste is scraped out of the holding pond and spread on the fields. Although this may be a major step forward in fighting farm pollution problems, it's only a partial solution. This wetland project is designed to attack contamination created by animal waste, not farm chemicals.
In addition to treating farm runoff, the project developers are hoping the wetland will attract birds and other wildlife. But area farmers are worried that the wetlands will attract the wrong kinds of animals, such as mosquitoes. But that shouldn't be the case if the wetlands are built right with the water flowing properly through the system. Similar projects attached to municipal sewage treatment plants have not proven to be magnets for mosquitoes.
Another problem is expenses. This wetland was funded by a $30,000 grant, and farmer Rodney Taylor says the high cost could be an obstacle.

TAYLOR: I didn't have $30,000, no, to put into this. That's the whole problem with this type of project. You've gotta have help from somewhere else. You know, farming these days, there's not that kind of money just available for the use of what we would consider... It's really not gonna put money back in our pockets.

JORDAN: But the cost of doing nothing could be even higher - pollution or high-tech water treatment plants. Before long, farmers may not have these choices. Lawmakers are concerned about this kind of non-point source pollution, and may enforce stricter water treatment standards for farms. For Living on Earth, this is Lorna Jordan.



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