The United States and the state of Arkansas filed an enforcement action last week against ExxonMobil Pipeline Company and Mobil Pipe Line Company in federal district court in Little Rock. The complaint concerns the March rupture in the companies’ Pegasus Pipeline in Mayflower, Ark.

The 20-inch diameter pipeline—originally built in the 1940s—carried heavy Canadian crude oil, which the complaint alleges spilled into a neighborhood and nearby waterways. Residential evacuations were ordered and cleanup efforts are ongoing.

In the complaint, the Environmental Protection Agency seeks “civil penalties and injunctive relief” under the Clean Water Act. Arkansas seeks civil penalties under that state’s Arkansas Hazardous Waste Management Act and the Arkansas Water and Air Pollution Control Act. It also seeks a judgment declaring ExxonMobil liable for cleanup and damages related to the spill.

ExxonMobil, in a statement on its website, says it will fully fund the cleanup. “We sincerely apologize for this incident and the disruption it has caused, and we thank the community of Mayflower for its continued support,” the company statement said.

The company said in a release in late May that “cleanup crews have removed all visible freestanding oil from the environment.”

“Progress continues, but we know our work is not complete,” said Mark Weesner, ExxonMobil incident commander. “We will be here until the job is done.”

 The pipeline runs from Patoka, Ill., to Nederland, Texas, about 850 miles in all.