DES MOINES — Voluntary efforts to prevent farm chemicals and nutrients from flowing into Iowa waterways are showing encouraging signs, but challenges remain for stemming pollution issues that are causing problems for states downstream, a federal regulator for the Midwest region said Friday.

Iowa embarked on a nutrient reduction strategy two years ago to promote conservation practices among farmers and to head off pressure from the U.S. Environmental Protection Agency to take over regulation of clean-water violations that pollute lakes and rivers in Iowa and downstream waterways.

Karl Brooks, administrator for the EPA's Midwest region, told a group of Iowa middle school students that progress has been made in getting the strategy into action, but he quickly added the work is "not finished, not complete, not yet a success but encouraging."

"It didn't get here yesterday, and it won't be solved tomorrow," he said.

Brooks said Iowa is a "really good laboratory" to study the voluntary efforts aimed at reducing the level of nutrients flowing into Iowa waterways that are generating environmental concerns because it plays into the state's strengths of land, food, water and community.

"The problem's there, it's a real problem, but the elements are there to come up with a solution," said Brooks, who traveled to Brody Middle School to discuss water-quality protection with a well-prepared group of seventh-grade students.

Brooks' classroom experience included a role-play exercise featuring six groups of students representing the EPA, scientists, farmers, concerned citizens, Des Moines Water Works and nonprofit organizations in framing the issue from a variety of perspectives that left the EPA administrator impressed with their depth of research.

"It's a complex problem involving land use, agriculture, politics and science," Brooks said. "The questions they asked indicated that more Iowans are focused on this and, if this is the coming generation, what I took away is that Iowa is going to be in really good hands because these are really good kids who are going to be great adults."

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Brooks also said the eyes of the nation will be watching Iowa as it works to encourage a landowner-driven approach to cleaning up its act on non-source pollution challenges.

"Because Iowa is one of America's leading agricultural states and it's also a state that is surrounded by America's two greatest rivers, Iowa does get the attention of the nation," he said.

"The nutrient reduction strategy is a really interesting and innovative approach that relies on the smarts that Iowans have used to grow food and manage land here for 150 years," Brooks added. "This agency is looking to see if the results over time show us if we're going in the right way and show us how to make improvements."