The rule also wants to reduce water withdrawal by 16.3 billion litres a year.

Altogether that is expected to give an estimated $US463 ($A660) million a year benefit.

“Today EPA is setting the first national limits to protect public health and reduce toxic pollutants including mercury, arsenic, lead and selenium released into America’s waterways by steam electric power plants,” EPA Administrator Gina McCarthy said.

“These cost effective, achievable limits will provide significant protections for our children and communities across the country, including minority and low-income communities, from exposure to pollutants that can cause neurological damage in children, cancer and other serious health problems.”

Each year steam electric plants discharge almost 30t of lead and 1.4t of mercury, 36t of arsenic, more than 100t of selenium, 13,800t of nitrogen and 309t of phosphorous.

About 14,750km of streams and rivers are damaged by steam electric discharges.

According to the EPA there are about 1080 steam electric plants and of those, 134 will have to make investments to meet the requirements of this rule.

The requirements do not apply to plants that are either oil-fired or smaller than 50 megawatts.