ST. PAUL, Minn. (AP) — Late changes to a plan seeking stricter rules on buffer zones separating farmland and public waterways speeds the timeline for compliance and carries possible fines of up to $500 for violators.

The modifications were made early Monday to suit Gov. Mark Dayton's objections to an earlier proposal he regarded as too lax. He made the buffer strip push a session priority in hopes of slowing agricultural chemical runoff into lakes and streams.

A compromise agreement calls for rooted-vegetation buffers of at least 30 feet in width but an average of 50 feet along public waters. The strips could be narrower along drainage ditches. Compliance deadlines would be late 2017 for public waters and 2018 for ditches.

Farmers who don't comply could face fines and orders for corrective action.