ST. PAUL (AP) — The Minnesota Supreme Court has ruled a western county in the state must conduct an environmental review to determine whether a proposed drainage ditch improvement could harm one of the last free-flowing creeks in the heavily agricultural area.

The ruling Wednesday affirms a state Court of Appeals judgment that reversed a Renville County Board decision which said the study wasn’t necessary. The Minnesota Center for Environmental Advocacy challenged the county’s decision.

It’s unclear whether the high court’s ruling will affect other conflicts around the state involving drainage projects that preserve farmlands but increase the volume of water and pollutants flowing downstream, the Star Tribune reported.

The Supreme Court said upper Limbo Creek is a public water, and therefore an environmental assessment must be conducted before a proposed drainage project can be allowed there.

The dispute involves proposed improvements to a century-old ditch that empties into the upper reaches of Limbo Creek. Backers say the project would lead to better drainage of farmland in the area.