Environmental Protection Agency (EPA) Administrator Andrew Wheeler wrote a letter to the Democratic governor citing multiple instances of California failing to meet federal water quality standards, noting that the problems are stemming from the state’s homeless population.

“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,” Wheeler wrote.

He added: “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.” Wheeler’s volley comes amid growing disdain between the two sides.

Newsom’s office dismissed the letter.

“There’s a common theme in the news coming out of this White House this week,” Nathan Click, a spokesman for Newsom, said in a statement to the Daily Caller News Foundation. “This is not about clean air, clean water or helping our state with homelessness. This is political retribution against California, plain and simple.”

President Donald Trump announced on Sept. 18 his decision to end California’s authority to craft emission regulations that are stricter than federal rules, a move that was long in the making. The Trump administration was working on removing the exemption since mid-2018.

California returned fire, with the state’s Attorney General Xavier Becerra, a Democrat who’s been a thorn in Trump’s hide, announcing a lawsuit against the administration in response. Becerra has sued Trump more than 60 times, most of which are related to the president’s regulatory rollbacks.

The EPA cited in the oversight letter that 202 water systems in California have reported drinking water problems. There are 82 areas in the state that don’t meet air standards for six pollutants. About three dozen other states also had counties that did not meet those national benchmarks.

Trump, for his part, is on record disapproving of California for its rampant homelessness and pollution.

“There’s tremendous pollution being put into the ocean because they’re going through what’s called the storm sewer that’s for rainwater. And we have tremendous things that we don’t have to discuss pouring into the ocean,” the president told reporters on the day he nixed California’s exemption. “You know, there are needles, there are other things.”

Trump officials threatened to withhold federal highway funding Tuesday from California, arguing the state has not made enough headway cleaning up its waterways. The president is also targeting California for being an incubator of vagrancy.

Trump reportedly sent aides from the Department of Housing and Urban Development to California in September and asked them to focus on Los Angeles, where people are camping on the sidewalks for miles. He is considering cleaning out the camps while building new facilities and for occupancy, The Washington Post reported.