INDIANAPOLIS — The U.S. Environmental Protection Agency has added a groundwater chemical plume in Indianapolis to its highest priority cleanup list for hazardous waste sites.

The EPA added the so-called West Vermont Drinking Water Contamination in Indianapolis and nine other U.S. sites Wednesday to its National Priorities List. That list lets the public and policy makers know which sites are deemed most in need of being cleaned up.

The Indianapolis Superfund site covers 18 acres where the groundwater is tainted with organic solvents.

The EPA connected nearby homes and properties to city water in 2015 after finding high levels of vinyl chloride in residential wells.

The EPA says that groundwater plume could still move toward additional residential wells and two municipal well fields which serve more than 18,000 Indianapolis residents.