“Temporary water use advisories will be posted where applicable and nearby residents and visitors should keep pets from drinking from these waters for at least three days,” the release said

The herbicide treatments target specific invasive aquatic plants, including variable water milfoil, fanwort, water chestnut, sacred lotus, and various algae species, according to the release.

Rhode Island and other states had recently won a ruling against HUD’s attempt to overhaul a federal homelessness grant program in fiscal year 2025.

US District Court Judge Mary S. McElroy found that HUD acted arbitrarily and capriciously in imposing illegal conditions on billions of dollars in funding for the Continuum of Care program, through which HUD distributes billions of dollars to state, local, and nonprofit agencies to support housing and services for people facing homelessness.

For more than two decades, HUD had followed a “Housing First” model, which prioritizes rapid placement in permanent housing without requiring people to first meet conditions such as sobriety or a minimum income threshold.

However, on June 1, the Trump administration moved forward with new rules for fiscal year 2026 that seek to re-implement a cap on permanent housing. The new Notices of Funding Opportunity will set aside $1.3 billion for transitional housing and supportive service-only grants — which the coalition of states say will have the effect of capping permanent housing projects at about 68 percent of the funds.

HUD Secretary Scott Turner announced the new terms on June 1, saying the old model didn’t work.

“The ‘housing first’ experiment failed Americans by warehousing the vulnerable without results. This ideology promised to end homelessness. Instead, billions of taxpayer dollars were spent while homelessness increased to record levels,” Turner said in a statement. “Housing alone will not solve a crisis driven by addiction and mental illness. Under President Trump’s leadership, HUD is making necessary reforms to put recovery first.”

HUD said that the new Notice of Funding Opportunity for $4.04 billion through the Continuum of Care homelessness assistance program would support organizations that facilitate treatment and recovery and “prohibit funding the widespread use of illicit drugs and distribution of paraphernalia.”

The lawsuit alleges that the new conditions will mean a large number of permanent housing projects funded by the Continuum of Care program will lose funding, which will lead to people being evicted, placing further strain on state and local governments.

“Instead of investing in programs that help people stay safe and housed, the Trump Administration has embraced policies that risk trapping people in poverty and punishing them for being poor,” the 44-page lawsuit alleges.

The shift threatens housing for at least 97,000 residents of CoC-funded permanent housing across the country according to the National Alliance to End Homelessness.

The states argue that HUD’s actions violate the Administrative Procedure Act for failing to proceed with notice-and-comment rulemaking, and for being arbitrary and capricious. They ask the court to declare that the challenged conditions are illegal and to block HUD from implementing them.

Along with Neronha, attorneys general from all New England states except for New Hampshire have joined the lawsuit. The coalition also includes attorneys general from Arizona, California, Colorado, Delaware, Illinois, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York, Oregon, Virginia, Washington, Wisconsin, and the District of Columbia, as well as the governors of Kentucky and Pennsylvania.

Amanda Milkovits can be reached at amanda.milkovits@globe.com. Follow her @AmandaMilkovits.