As The Eye  has reported, state environmental budget cuts have hit water-quality monitoring especially hard, with testing for bacteria in lakes and rivers falling by two-thirds since 2001.

So why does Gov. Charlie Baker, who has proposed further cuts in environmental spending, want the state to take on even more water oversight from the federal government?

Baker filed legislation in April to transfer authority from the U.S. Environmental Protection Agency to the state Department of Environmental Protection to regulate pollution discharges into waterways from businesses, wastewater treatment plants and other entities. All but three other states have taken over primary oversight from the EPA in this area.

Martin Suuberg, DEP’s commissioner, argued for the bill at a legislative hearing last week. He told The Eye in an interview that it was time “we joined 46 other states in administering this program.’’ Suuberg called it “beneficial and helpful to manage water resources holistically.’

Environmentalists and some state legislators disagree. At the Environment Committee hearing, state Sen. Jamie Eldridge, an Acton Democrat, highlighted The Eye’s story, which reported a 29 percent drop in environmental spending over the last 15 years.

“It makes no sense to give MassDEP yet another major responsibility with insufficient resources,’’ Julia Blatt, executive director of the Massachusetts Rivers Alliance, said in an email. “This is especially poor policy when the EPA is already providing us with this program at no cost to the state budget.”

State officials say taking on the new program would cost the state about $4.7 million a year, which is not in the governor’s budget for fiscal year 2017 beginning in July. If authority is transferred, the governor has pledged to back the added funding, which would support about 40 full-time positions for enforcement, monitoring and analysis.

Massachusetts has long contemplated taking over the authority from the EPA. But the last time it was analyzed in 2013, DEP officials estimated that it would cost $9 million to $10 million to take over the program, and concluded that the state didn’t have the money.

Suuberg said the costs could be lower now because those estimates included information-technology upgrades already being done, and because the state would also work with non-profits to help with water quality tracking.

Environmentalists worry the move is really about friendlier environmental policies toward businesses.

“The feds are buffered from political pressure to issue permits much more so than the state,’’ emailed Jack Clarke, director of public policy for Mass Audubon, which opposes the authority transfer.

If the legislation passes, the EPA will have final authority to decide whether the state can take over the program.