The agency weakened Obama-era rules meant to keep metals and other pollution out of rivers and streams, saving industry tens of millions of dollars.

The Trump administration on Monday relaxed strict Obama-era standards for how coal-fired power plants dispose of wastewater laced with dangerous pollutants like lead, selenium and arsenic, a move environmental groups said would leave rivers and streams vulnerable to toxic contamination.

The Environmental Protection Agency regulation scaled back the types of wastewater treatment technologies that utilities must install to protect rivers and other waterways. It also pushed back compliance dates and exempted some power plants from taking any action at all.

The change is one of several the Trump administration has pushed to try to rescue a coal industry in steep decline, extending the life of aging coal-fired power plants and trying to make them more competitive with cheaper natural gas and renewable energy. The move came days after President Trump’s son Eric described his father as a champion of coal miners who “will fight for you.”