– The Trump administration plans to roll back an Obama-era regulation that was designed to limit dangerous heavy metals like arsenic, lead and mercury from coal-fired power plants, according to two people familiar with the plans.

With a series of new rules expected in November, the Environmental Protection Agency (EPA) will move to weaken the 2015 regulation by relaxing some of the requirements on power generators and also exempting a significant number of power plants from even those weakened requirements.

The effort was designed to extend the life of old, coal-fired power plants that have been shutting down in the face of competition from cheaper natural gas and renewable energy. Environmental groups warned that the move could lead to health problems caused by contaminated drinking water, including birth defects, cancer and stunted brain development in young children.

A spokesman for the EPA did not respond to a request for comment. Agency officials held a conference call Tuesday with supporters of the Trump administration's deregulatory efforts to discuss the measure, multiple people confirmed.

The move is part of a series of efforts by the Trump administration to relax restrictions on coal-fired power plants and promote the construction of new ones even as market forces continue the industry's decline and scientific evidence mounts about the need to reduce fossil fuel use to avert catastrophic climate change.

According to the EPA, about 1.1 million Americans live within 3 miles of a coal plant that discharges pollutants into a public waterway. The 2015 rule set deadlines for power plants to invest in modern wastewater treatment technology to keep toxic pollution out of local waterways. The regulation also required them to monitor local water quality and make more information publicly available. The Obama administration estimated the regulations would stop about 1.4 billion pounds of toxic metals and other pollutants from pouring into rivers and streams.

But the rule would have also raised the cost of operating the plants, further endangering their economic viability.