Gov. Mark Dayton touted his signature effort to improve Minnesota water quality Thursday even as Republicans in the Legislature move to delay and change the law.

Dayton's plan to surround state waterways with buffer strips of vegetation to protect them from farm runoff passed with bipartisan support in 2015 but has faced ongoing resistance from agribusiness interests and lawmakers who represent farm districts.

The Dayton administration reports that about three quarters of Minnesota counties have achieved compliance of between 60 and 100 percent on the buffer bill. By Nov. 1, 2017, landowners have to have 50-foot-wide buffers in place on lands adjacent to public waters.

The vegetation buffer strips filter farm runoff while also firming up the bank of the waterway. The effort is intended to prevent fertilizers like phosphorus and nitrogen as well as sediment from polluting lakes, rivers and streams.

A 2015 report from the Minnesota Pollution Control Agency showed that half the lakes and streams in southern Minnesota are not safe for fishing or swimming.

"This is about protecting the water for ourselves, our neighbors downstream and future generations," Dayton said at a news conference, joined by several of his commissioners and a farmer.

But resistance remains fierce in some quarters.

Rep. Jeff Backer, R-Browns Valley, who co-authored a bill to repeal the buffer legislation that he voted for in 2015, said the state should rely on the wisdom and prudence of farmers for water quality: "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."

Dayton was asked if he would negotiate with Republicans seeking to change the law or delay implementation.

"No," he said.

Backer said he was "disappointed with this statement that appears to draw a line in the sand."