PLAQUEMINE — The Louisiana Supreme Court said Tuesday it wouldn't order changes in how groundwater is being cleaned up near Plaquemine, but added that residents are free to ask regulators for a new assessment.

In 2013, a court found Dow Chemical Corp. responsible for elevated levels of certain chemicals in the Upper Plaquemine Aquifer. Dow was ordered to pay for "monitored natural attenuation," a remedy that uses naturally occurring bacteria to neutralize the threat to human health over time. The company also had to put up a $3.2 million bond.

In 2024, area residents said the cleanup was taking too long. A district judge rejected their arguments, saying state and federal agencies overseeing the cleanup hadn't said changing plans was necessary. The 1st Circuit Court of Appeal reversed the denial and said the lower court should hear the residents' claims.

Dow appealed, and the state Supreme Court sent the case back to the lower court Tuesday. Justices said the state Department of Environmental Quality and U.S. Environmental Protection Agency maintain jurisdiction over the site, and added that the lower court was correct to defer to them.

The Supreme Court said residents could ask the government agencies to assess whether the remediation plan is working or should be changed.