Outdoors

Forum explores relationship between karst, livestock operations and water quality

Ag officials share troubling example from Wisconsin

NE Iowa Watershed and Karst Map
NE Iowa Watershed and Karst Map

DECORAH — Though it provides little solace for northeast Iowans worried about the impact of livestock confinements in areas of karst topography, attendees at a daylong forum on the subject at Luther College learned last week that residents of Wisconsin’s Kewaunee County have even worse water quality concerns.

“Brown water that smells like manure,” said Mark Borchardt, a microbiologist with the U.S. Department of Agriculture.

Kewaunee County, which borders Door County to the north and Lake Michigan to the east, has about 100,000 dairy cattle and 16 confined animal feeding operations, Borchardt said.

It is also underlain by fractured limestone and dolomite bedrock, much of it less than 5 feet beneath the surface, through which bacteria from manure and other pollutants can readily enter groundwater.

“It’s a massive interconnected pipe system with little or no attenuation of contaminants before they enter groundwater,” he said.

Borchardt said his research shows that cattle manure applied to farm fields as fertilizer is the main source of private well contamination in Kewaunee County.

Borchardt’s study, which used bacteria DNA to identify the source of pollution, found that human sanitary systems contributed the most pollution during dry periods, while polluted water was linked to cattle during wet periods when groundwater was being recharged.

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Overall, he said, of 131 wells sampled, 40 tested positive for cattle manure, while 29 tested positive for human waste and seven tested positive for both.

Kewaunee County Conservationist Davina Bonness said 30 percent of the wells tested in the county have shown unsafe levels of coliform bacteria, E. coli bacteria or nitrates.

The county’s prominent karst topography shows up not only as numerous sinkholes, she said, but also in aerial photos as networks of greener vegetation where water settles in shallow bedrock cracks.

Bonness said she and colleagues document “one or two brown water incidents each year,” though undocumented reports are much more common.

Bonness reported some progress in a decadelong effort to tighten state laws on the application of manure in Kewaunee and other karst-dominated counties, but she noted that any restrictions remain voluntary.

Monte Marti, an opponent of a proposed swine concentrated animal feeding operation — or CAFO — in a karst region of Allamakee County, hailed the May 30 forum “as a great way to present facts” about the relationship between karst, livestock and water quality.

The Kewaunee County situation, he said, shows “it takes a long time for change to come.”

“Karst is the key to getting the laws on CAFOs changed,” said attendee Sue George, a spokeswoman for Northeast Iowans for Clean Air and Water, a group of Howard County residents opposed to the construction of a pair of 2,499-head swine finishing facilities in a region riddled with sinkholes.

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“If everyone could only understand what is going on underneath the soil on karst terrain, they would surely think twice about building on it,” she said.

Iowa law requires that livestock confinements be set back 1,000 feet from known sinkholes and that manure cannot be applied within 200 feet of a sinkhole, said Gene Tinker, animal feeding operations coordinator for the Department of Natural Resources.

Tinker acknowledged “greater risk in karst,” but said operators following the rules “can mitigate much of it.”

State Geologist Bob Libra said sinkholes provide “an open conduit to groundwater.”

CAFO siting rules, he said, are predicated on known sinkholes, which does not account for recently opened sinkholes or sinkholes that had been plugged but later reopened.

“There is no reporting system for sinkholes, and there never has been,” he said.

Winneshiek County Supervisor John Beard, a former state legislator, said state rules “have taken away local officials’ ability to do anything but comment on the siting of CAFOs.”

The rules are ineffective and should be changed to provide more protection for the health of local residents and the environment, he said.

Beard said the boards of supervisors in 12 Iowa counties, including his, have petitioned the Legislature to revisit CAFO siting rules.

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