The U.S. Supreme Court heard arguments last week over whether the U.S. Environmental Protection Agency should look at muddy water running off logging roads in the same way as muddy water running off a farm field, a nonpoint source, or instead like the discharge pipe from a factory, a point source.

The Northwest Environmental Defense Center originated the case when it sued the Oregon Department of Forestry over roads on the Tillamook State Forest.

Citing the federal Clean Water Act, the group claimed water running through ditches and culverts designed and constructed to handle stormwater on logging roads that ends up in rivers should need the same kind of permit a factory needs.

An attorney for the group claims industrial logging needs to follow industrial regulations. Muddy runoff from unpaved logging roads in the mountains is blamed for sediment build-up in stream bottoms and is considered harmful to salmon and other fish.

In Northwest Montana, muddy runoff from logging roads has impacted nesting sites for native bull trout, called redds. But after decades of restoration efforts, one impacted stream, Big Creek in the North Fork, will be removed from the state’s list of sediment-impaired waters, it was announced in April.

The timber industry claims that requiring permits for all the culverts and ditches would be too expensive — perhaps $1.1 billion nationwide — and cost thousands of jobs. They also claimed they use best management practices when building logging roads.

The environmental group lost in U.S. District Court in Portland, Ore., but won in the Ninth Circuit Court of Appeals in San Francisco. The Oregon Department of Forestry and Georgia Pacific-West appealed the case to the U.S. Supreme Court.

The Obama administration petitioned the U.S. Supreme Court not to hear the case, arguing that the appellate court ruled incorrectly and that Congress and the EPA were taking steps to address the situation.

The U.S. Supreme Court took up the case on Dec. 3. The EPA, however, issued a new rule three days earlier stating that runoff from logging roads should be considered a nonpoint source just like runoff from farm fields. That last-minute ruling could affect any decision the high court makes.