Looking at the same data, the Environmental Protection Agency and the Missouri Department of Natural Resources came to very different conclusions about the quality of Missouri's streams.
The EPA identified 135 Missouri water bodies the state should have listed as polluted under the U.S. Clean Water Act.
In Boone County, Bonne Femme Creek, Fowler Creek and Lake of the Woods are among those identified by the EPA.
In its decision on the state's 2006 list of impaired waters, the agency cited flaws in the methods the state Department of Natural Resources used to determine which streams should be on the list.
The Clean Water Act demands that every two years each state submit a list of water bodies that don't meet water quality standards and don't have specific limits on any pollutants discharged or running off into them. Putting a water body on the list is the first step toward clean-up efforts.
The EPA found that Missouri used an unapproved, more lenient bacteria standard that was about four times higher than the EPA-approved limit, according to the EPA's decision document.
Rebecca Landewe, an EPA Missouri water quality standards coordinator, said DNR's standard was approved by the state at the time, but the EPA subsequently tossed it out as unacceptable in light of new evidence.
"I don't think they were intending to use something inappropriate," Landewe said.
The decision document also says the state made errors in calculating data. It noted that the state did not list any water bodies as polluted by mercury.
In a public notice at the time, the state said it didn't want to list these waters because it didn't want to imply that only these waters were affected by mercury.
Most of the mercury in lakes and streams is deposited from the atmosphere. According to the EPA Web site, two thirds of the mercury in the atmosphere is from human sources such as coal-fired power plants. Winds may blow it in from other countries, which can complicate regulation.
But instead of not listing any water body as polluted by mercury, EPA's decision on the 2006 list reflects a different approach.
"We think that if there is data that shows a stream is impaired, it needs to be on the list," Landewe said.
The EPA, in a news release, said it expects the issues brought up by its actions will be addressed in Missouri's 2008 version of the list.
A draft of the state's 2008 list released Sept. 23 reveals that the DNR took a new approach and listed more than 20 streams as impaired by mercury. However, the two lists aren't a perfect match.
The same bacteria standard not approved by the EPA was used by the state to assess the quality of streams on the 2008 list, although the department listed streams that violated EPA's stricter standard on a separate, unofficial list.
John Ford of DNR said the state might have to make changes to its draft of the 2008 list because of the EPA's decisions.
"We would have used the 2006 list to draw up the 2008 list," Ford said. "In this case we had to go ahead and make the 2008 list without the benefit of the 2006 list."
Landewe said the state and EPA are discussing how to work this out and have had telephone conversations on the matter.
Ken Midkiff, chair of the Missouri Clean Water Campaign, said he thinks the EPA came to the right decision.
"My concern is that there are a number of streams in or near urban areas that are not safe for human contact. But a lot of people don't know that," Midkiff said. "The streams aren't posted."
The EPA's list is open for public comment until Nov. 24.