WASHINGTON (AP) — The Environmental Protection Agency says it is going forward with a new federal rule to protect small streams, tributaries and wetlands, despite a court ruling that blocked the measure in 13 central and Western states including Idaho.

The EPA says a rule that took effect Friday in 37 states will safeguard drinking water for millions of Americans. Opponents, including farm and business groups, have pledged to fight the rule, emboldened by a federal court decision Thursday that blocked the rule from Alaska to Arkansas.

Other lawsuits seeking to block the rule are pending across the country, and the Republican-controlled Congress has moved to thwart it. Opponents call the rule federal overreach. The EPA says it clarifies which smaller waterways fall under federal protection after two Supreme Court rulings left that uncertain.