Gov. Mark Dayton has directed his agriculture department to move forward with its proposal for reducing nitrate levels in groundwater in farm country, despite an effort by GOP lawmakers to block it.

The House and Senate agriculture committees published notices in the State Register on Monday prohibiting adoption of the rule until after next year's legislative session, which adjourns May 20, 2019.

But Dayton spokesman Matt Swenson says the Democratic governor believes he still has authority to proceed with the rulemaking.

The rule would create voluntary and mandatory practices to limit seepage of nitrates from farm fertilizer into groundwater. Excessive nitrates can be toxic, especially to babies, and are an expensive problem for some communities.

Dayton says Minnesotans deserve the cleaner drinking water he says the plan will deliver.