HOUSTON (Reuters) - Sixteen coal ash pits in Texas are leaking contaminants into groundwater, including arsenic, boron, cobalt and lithium, according to a report released on Thursday by the Environmental Integrity Project (EIP).

The TXU Monticello Steam Electric Station power plant is seen near Mt. Pleasant, Texas February 26, 2007. TXU Corp.'s plans to scrap the construction for several new coal-fired power plants represents a dramatic shift in the battle against global warming but falls short of proving the company had turned over a new, greener leaf, environmentalists said on Monday. REUTERS/Mike Stone (UNITED STATES)

Coal ash is the residue left after coal has been burned to generate power, and can include sludge from plant exhaust stacks. Coal ash is placed in pits or ponds next to coal power plants.

The report from the national environmental group also said a federal rule governing coal pits would not prevent groundwater contamination.

“A history of weak regulatory oversight has led to this problem, and only a stronger regulatory framework can fix it,” the report said. “Unfortunately, neither the federal Coal Ash Rule nor Texas’s proposed coal ash program rise to that challenge.”

The pollutants leaking into groundwater from coal ash pits can potentially can cause cancer and damage the human brain, heart and lungs, the EIP report said.

U.S. President Donald Trump has pushed for looser regulations for coal plants as part of a campaign pledge to boost coal production.

A 2016 federal law allows states to develop their own coal ash regulations. The Texas Commission on Environmental Quality (TCEQ) issued a draft coal ash program in August.

TCEQ spokeswoman Andrea Morrow said on Thursday the agency does not comment on reports from other organizations.

The EIP was one of three environmental organizations that asked a federal court in September to invalidate a coal ash program adopted by the state of Oklahoma.

Abel Russ, an attorney and co-author of the report, said Texas may face a legal challenge to its coal ash program.

“If the Texas rule is weaker than the federal standard, it’s safe to assume there will be a legal challenge,” Russ said at a news conference on Thursday.

Morrow said the draft Texas rule was being revised to match changes in the federal rule.

“A rule to create a program for the management of coal ash in Texas is in development,” she said. “The TCEQ continues the process of revising the draft rule due to changes to the federal coal ash rule.”

Three of the power plants covered by the EIP report were shuttered in 2018, but the coal ash pits remain.

Texas receives 24 percent of its electrical power from coal.