A settlement filed with the U.S. Court of Appeals for the Ninth Circuit would require the U.S. Environmental Protection Agency (EPA) to revise its 1999 Phase II Municipal Separate Storm Sewer System (MS4) permits for small communities with populations fewer than 100,000.

EPA reached a settlement with the Natural Resources Defense Council (NRDC) and the Environmental Defense Center Inc. Under the settlement, the agency would be required to propose a revised rule by Dec. 17, 2015, and issue a final rule by Nov. 17, 2016. Additionally, EPA would be required to determine, by May 26, 2016, if it will regulate stormwater runoff from forest roads.

The groups signed the proposed settlement Aug. 26. The court has 45 days to approve it.

Because of the settlement, the petitioners have agreed to withdraw a December 2014 lawsuit against EPA. This lawsuit claimed that the agency did not follow through on requirements of a 2003 Ninth Circuit court ruling on Phase II MS4 permits and forest road stormwater runoff. The 2003 ruling required EPA to address procedural issues within the Phase II rule related to issuing Notices of Intent under the small MS4 General Permit option. According to the 2003 case, without public review and approval of permits, the rule lacked assurance that regulated communities would reduce stormwater pollution to the maximum extent practicable as required by the Clean Water Act.