– Gov. Mark Dayton promised Friday to fight efforts at the Legislature to weaken or delay his signature 2015 water quality initiative, the nation’s first law requiring agricultural landowners to install and maintain vegetation buffers near rivers and streams to protect against farm runoff.

“I compromised on this bill, and I’m not going to compromise on it anymore,” he told a crowd gathered at the University of Minnesota, Morris, for a “water summit” convened by his administration.

“I’m not going to rescind it, water it down, delay its implementation,” Dayton said, anticipating a push by the newly Republican Legislature for changes to a law many farmers say is burdensome and violates their property rights.

One measure introduced recently by a group of House Republicans would repeal the entire law.

Dayton’s tough tone illustrates the political and economic challenges in trying to win lasting legislative victories on the clean water front, which has become one of the DFL governor’s top priorities in recent years. Minnesota’s agricultural and business communities are embroiled in a contentious debate with environmental and clean-water advocacy groups over the responsibilities for and costs of water pollution.

Passed into law in 2015 after extensive negotiations with the GOP-led House and DFL-controlled Senate, the buffer law was heralded by environmental groups but opposed by leading farm groups.

It was designed to strengthen existing law, which gives counties authority to require 16.5-foot buffers on drainage ditches and 50-foot buffers on streams, lakes and wetlands. Those rules were confusing and rarely enforced, and many buffers are missing. Dayton’s law clarified the rules and added financial penalties.

But for Dayton and his fellow DFLers in rural Minnesota, the law came with political consequences. Though many factors contributed, the DFL lost badly in greater Minnesota in the November election.

Dayton acknowledged the blowback, joking that he is known as the “buffer bully.”

In response to Dayton’s remarks Friday, Rep. Jeff Backer, R-Browns Valley, said: “It’s easy to grandstand.”

Backer, who represents the Morris area and attended the water summit, said he expects ongoing negotiations to improve a law he called flawed: “On this issue we have to look at the people on the ground — the landowners, the farmers — because they are good stewards of their land. This is their production, and they want to protect their investment,” said Backer, a cosponsor of the repeal measure in the House.

The water summit — part of a yearlong effort by Dayton to bring attention to Minnesota’s water quality challenges — comes at the end of an eventful week for the second-term governor, who very publicly fainted on Monday night during a major speech, then revealed a cancer diagnosis the next morning.

As he often does, Dayton used self-deprecating humor to lighten the mood. “I don’t know if they came here to hear my speech or to see if I would pass out,” he said of media coverage of the summit.

Dayton told the crowd that he would continue pushing for clean water initiatives during his final two years in office.

In January, he again proposed spending $167 million to help small cities improve water infrastructure. That would only begin to offset the need: The federal Environmental Protection Agency has estimated Minnesota will need to spend $11 billion to maintain and upgrade its water systems during the next 20 years.

Last week, he announced a state-federal deal to provide $350 million from the U.S. Department of Agriculture and $150 million in state funds to a conservation program that pays farmers to idle vulnerable land near waterways.

“I have no sympathy or patience for those who continue to deny we have a water pollution problem or refuse to do anything about it,” Dayton said.

In his State of the State speech Monday, Dayton said, “What does it say about ‘The Land of Sky Blue Waters’ when families can’t swim safely in nearby lakes? What does it say when local rivers and streams are so polluted that fish and other wildlife cannot live in, or around, them?”