A buffer strip of grass and trees along the Rock River west of Edgerton, Minn. Gov. Mark Dayton, battling House Republicans, retreated from a controversial component of his new water quality law, saying he has instructed the state's environmental agency to stop mapping private ditches around the state. (The Minnesota Star Tribune)

Gov. Mark Dayton on Friday lashed out at House Republicans and retreated from a controversial component of his new water buffer law, saying he caved to GOP threats to withhold funding for other water-quality improvements he wants.

"In the face of those threats, and the likelihood they'd be carried out … I decided to strategically drop [mapping of private ditches] from the existing practice of the DNR," Dayton said Friday. He added: "We'll have other opportunities to remedy it" in the future.

At issue is a requirement under last year's water-quality law that instructed the Department of Natural Resources to map private ditches, which would be required to have 16.5-foot wide strips of natural vegetation, beginning in November 2018.

Other bodies of water would be required to have wider buffers, which are intended to reduce water runoff and soil erosion and to improve water quality. A state report last year found that half of Minnesota lakes and rivers in southern Minnesota are too polluted much of the time to allow swimming or fishing.

The issue has pitted Dayton against some farmers, who don't want to lose additional land that could be used to plant crops.

Legislative leaders say that ditches on private land were never part of the original compromise negotiated among legislators, Dayton's office and farm groups.

House Speaker Kurt Daudt, R-Crown, denied threats were made, saying: "We don't operate that way."

Daudt and other Republican leaders had in recent days met with Dayton, after raising the issue with the state's environmental agency in November. Dayton in a news conference said Republicans had threatened to spurn his bonding proposals for the DNR and the Minnesota Board of Water and Soil Resources.

Daudt acknowledged the mood in recent meetings was strained: "I know that tensions probably got high in the conversations, and there probably were some conversations between members and others that may reflect that."

Dayton's administration has contended private ditches were also covered by the new law, pointing to the statute language that said the 16.5-foot buffer requirement applied to "ditches within the benefited area of public drainage systems."

The final language on the buffer proposal was approved during last summer's special legislative session.

Dayton's original proposal would have required wider buffers, but intense opposition by farmers resulted in the final compromise law.

Doug Peterson, president of the Minnesota Farmers Union, said he was happy to see Dayton halt the mapping of ditches on private land.

"It was never discussed and never agreed to," said Peterson, a former legislator.

He said he expects more debate on other water-quality efforts that would affect farmers.

Steve Morse, executive director of the Minnesota Environmental Partnership, said he was disappointed in the development.

The issue was tough to track last year, he said, because of the secrecy surrounding the negotiations. The result, he said, was a law that evidently applied to ditches on private land, as well as public ditches.

"Legislative intent does not trump clear language," he said.

Republicans offered a November letter from two legislative leaders who have jurisdiction over environmental issues, Rep. Denny McNamara, R-Hastings, and Sen. David Tomassoni, DFL-Chisholm, to DNR Commissioner Tom Landwehr.

"It has come to our attention that the Minnesota Department of Natural Resources is making a mistake in its interpretation of the new buffer law that was passed in the special legislative session [last year]," the letter said.

"The DNR's attempt to include anything other than public ditches on the guidance maps it is creating goes far beyond the agreement the House and Senate negotiated with DNR, Board of Water and Soil Resources and Gov. Dayton's office," the letter said.

Rep. Paul Torkelson, R-Hanska, said in a statement that the GOP wants to ensure better water quality, as well.

"Our agricultural community understands and supports land management practices that will help improve water quality," said Torkelson, a farmer and chairman of the House Capital Investment Committee. "We are pleased the governor agreed Thursday to uphold the legislative intent of the new buffer law."

Ricardo Lopez • 651-925-5044