• The DOJ filed a lawsuit against Norfolk Southern on Thursday, alleging Clean Water Act violations in the railway company's Ohio derailment last month.
• The state of Ohio has also sued the company over environmental impacts of the derailment.
• Senators recently introduced a new railway safety bill in light of Norfolk Southern's derailment.

The Justice Department said Friday it filed a lawsuit against Norfolk Southern, aiming to hold the railway company accountable for alleged Clean Water Act violations that allegedly occurred due to an Ohio train derailment in early February.

In February, a Norfolk Southern train carrying hazardous chemicals derailed near the Pennsylvania border in East Palestine, Ohio, causing a fire, collisions and local evacuations.

The lawsuit, filed Thursday on behalf of the Environmental Protection Agency, seeks "injunctive relief, cost recovery, and civil penalties" for the alleged violations.

"With this complaint, the Justice Department and the EPA are acting to pursue justice for the residents of East Palestine and ensure that Norfolk Southern carries the financial burden for the harm it has caused and continues to inflict on the community," Attorney General Merrick Garland said in a release Friday.

In an emailed statement to CNBC, a Norfolk Southern representative said the company's focus "right now is to make progress every day cleaning up the site, assisting residents whose lives were impacted by the derailment, and investing in the future of East Palestine and the surrounding areas."

"We are working with urgency, at the direction of the U.S. EPA, and making daily progress," the spokesperson continued. "That remains our focus and we'll keep working until we make it right."

Since the derailment, Norfolk Southern has been in hot water with state and federal officials concerning the environmental implications of the derailment.

The state of Ohio has also sued Norfolk Southern in a bid to ensure the company pays for environmental damage and cleanup efforts, which Norfolk Southern CEO Alan Shaw has said the company would continue to support. Shaw and several government officials have said it's safe to live in the area, but residents have complained of illnesses.

In a statement regarding Thursday's lawsuit, EPA Administrator Michael Regan said "no community should have to go through what East Palestine residents have faced."

He added that the lawsuit marks the agency's "commitment to ensure Norfolk Southern cleans up the mess they made and pays for the damage they have inflicted as we work to ensure this community can feel safe at home again."

On Thursday, three senators introduced a new rail safety bill in a bid address long-standing concerns that became more acute in light of the Norfolk Southern derailment.

Last week, Shaw told senators his company supports portions of an adjacent bill, the Railway Safety Act, which includes provisions calling for two-person crews on all freight trains. That was one sticking point, as Shaw said the company was "not aware of any data that links crew size with safety."

Otherwise, Shaw said in prepared remarks that he agrees in "principle" with portions of the legislation, such as "establishing performance standards, maintenance standards, and alert thresholds for safety sensors."

The new bill, dubbed the Railway Accountability Act, would direct the Federal Railroad Administration to study wheel-related failures and derailments and other mechanical defects.

It would also enact new brake safety measures and ensure railways equip workers with sufficient reporting and safety equipment.

A National Transportation Safety Board preliminary report pointed to an overheated wheel bearing on the Norfolk Southern train that derailed, without offering a precise cause for the derailment.

–CNBC's Noah Sheidlower contributed to this article.