MADISON, Wis. (AP) — Republican Attorney General Brad Schimel has joined 18 other GOP attorneys general in asking the U.S. Supreme Court to overturn a ruling that Clean Water Act protections extend to non-point pollution.

The case stems from a 2014 gasoline pipeline leak in South Carolina. Conservation groups sued in 2016 alleging pipeline owner Kinder Morgan Energy Partners is violating the CWA. The groups argue that even though the pipeline has been repaired thousands of spilled gallons from the leak are seeping through the ground into nearby waters.

Schimel joined with 10 other states in arguing that adopting the groups' stance would erode states' regulatory role. A federal appellate court ruled in the conservation groups' favor.

Earlier this month Schimel and the other GOP attorneys general filed a brief with the high court urging the justices to overturn the ruling.