EPA Administrator Andrew Wheeler has accused California of “failing to meet its obligations” to protect the environment, claiming that the state’s growing homeless population threatens its water quality. In an oversight letter, Administrator Wheeler charged California officials with failing to meet federal health standards in numerous communities where large homeless populations litter the streets with trash, drug paraphernalia and human waste. The letter went on to argue that California’s focus on global warming has come at the expense of more basic environmental protections. Specifically, the oversight letter cited 202 California water systems that have recently reported drinking water problems and 82 areas that don’t meet air quality standards for six pollutants.

“The agency is aware of the growing homelessness crisis developing in major California cities, including Los Angeles and San Francisco, and the impact of this crisis on the environment,” Administrator Wheeler wrote “Based upon data and reports, the agency is concerned that California’s implementation of federal environmental laws is failing to meet its obligations required under delegated federal programs.”

Under specific circumstances, the EPA can take over enforcement of federal pollution laws from state agencies. In the letter, Administrator Wheeler gave California Gov. Gavin Newsom until the end of October 2019 to demonstrate that state officials have “adequate authority and capability to address these issues.”

The letter is the latest action by the Trump administration in what appears to be a new strategy in its conflict with California state officials. In the last month, national agencies have moved to revoke California’s right to limit air pollution from cars, begun investigating an agreement between California and four automakers for possible antitrust violations and threatened to withhold federal highway funds if California does not do more to clean up its air.

California state officials have rejected the claims linking increasing homelessness to environmental issues. “There’s a common theme in the news coming out of this White House this week. The president is abusing the powers of the presidency and weaponizing government to attack his political opponents,” Gov. Newsom’s spokesman said. “This is not about clean air, clean water or helping our state with homelessness. This is political retribution against California, plain and simple.”

Administrator Wheeler’s letter marks the latest flashpoint in the conflict between federal and California environmental legislators. Additional litigation is a certainty if the federal government moves to further restrict California’s ability to enforce environmental regulations. Yet again, businesses will be facing an uncertain regulatory climate as these two titans continue to square off in a fight over the extent of their authority.