The US Environmental Protection Agency said Thursday that it is investigating whether Mississippi state agencies discriminated against the state’s majority-Black capital city by refusing to fund improvements for its failing water system.

The announcement came days after leaders of two congressional committees said they were starting a joint investigation into a crisis that left most homes and businesses in Jackson without running water for several days in late August and early September.

Heavy rainfall in late August exacerbated problems at Jackson’s main water treatment facility. The Republican governor, Tate Reeves, declared an emergency 29 August, and the state health department and the Mississippiemergency management agency have been overseeing operations and repairs at the facility since then.

About 80% of Jackson’s 150,000 residents are Black, and about a quarter of the population lives in poverty. By the time Reeves issued the emergency order, Jackson residents had already been told for a month to boil their water before to kill possible contaminants.