THE TEMPERATURE is continuing to climb in the growing feud between the state’s largest drinking water provider and communities that surround its main water source.

The Massachusetts Water Resources Authority is seeking approval from state officials for a high-stakes push to draw an additional 20 million gallons of water per day from the Quabbin Reservoir so that, the agency says, it can serve new communities in the eastern part of the state.

It would by far be the largest such request since the MWRA was formed in 1984 — three times as much as the next-highest approved plan to pull more water out of the state’s largest drinking water source in order to serve a new community.

The proposal is further stoking tensions that are already playing out in a separate dispute between rural, financially strapped communities that surround the Quabbin Reservoir and the agency charged with providing clean drinking water to its customers mostly in Eastern Massachusetts. The focus of that dispute is the towns’ agreement not to develop land in the Quabbin watershed in exchange for payments in lieu of taxes from the state that grossly undervalue what the land would be worth if the municipalities were able to collect property tax revenue on it.

For the MWRA, a quasi-public agency that serves 61 municipalities mostly in and around Greater Boston, the new water withdrawal plan, which requires the green light from the state Water Resources Commission, makes sense all around.

As the state pursues more housing and as municipal water sources and private wells suffer from contamination and dwindling supplies due to a two-year drought that’s only now starting to subside, the MWRA believes it can be the answer, selling more high-quality water from a Quabbin Reservoir that can withstand greater withdrawals.

Those living near the Quabbin disagree — and are mobilizing to kill the proposal. They fear the precedent such a move would set, and it feeds their sense that the agency will only continue to take the water that they protect and send it east to support growth there while their towns in Central Massachusetts face an increasingly alarming budgetary crunch.

“We’re not giving up until there’s fairness,” state Sen. Jo Comerford, a Democrat who represents Quabbin-area towns, said in an interview. “This is not what fairness looks like. This would set a really dangerous precedent — that’s not hyperbolic — that an entity like the MWRA can get basically a lock on the water to use at its discretion without the transparent, accountable public oversight on this precious resource.”

Part of the contention around the plan, which will face a grilling at a public hearing next week in Belchertown, is its sheer size. The MWRA has never asked the state to approve additional withdrawals from the Quabbin at anywhere close to what the agency is now seeking.

If nothing else, Comerford said, it’s questionable optics for the MWRA to pursue a project of this size after facing scrutiny for not requiring its customers in Greater Boston to take conservation measures during the drought while residents living in localities near the Quabbin, which don’t drink water from the reservoir, implemented stricter steps to reduce water demand and protect the watershed.

But the part of the plan that’s arguably generating the most blowback is the process the MWRA is deploying to win approval from state officials.

Water transfers like the one proposed here are governed by a 40-year-old law known as the Interbasin Transfer Act. Typically, state officials review environmental records and water demand documents from both the “donor basin” — the water resources that will be sending water somewhere else — and the “receiving basin” — the area that will be taking in more water. The goal is to ensure that there aren’t adverse impacts to the donor basin that’s losing water and that there is a legitimate demonstrated need for the transfer to occur.

For the first time in state history, though, the MWRA is asking the Water Resources Commission to review the agency’s donor basin proposal separately and ahead of any receiving basin requests that may come in the future. Those would still need to be individually reviewed by the commission.

The move, if approved, would essentially grant the MWRA the ability to have the donor basin approvals in hand if and when new communities are approved to receive the water and join the system.

It could, depending on your perspective, save on long permitting processes by avoiding the agency coming in with a new analysis every time a new community wants a share of the Quabbin, giving state officials a more holistic look at the MWRA’s goals — or recklessly sever the commission’s ability to look at the tradeoffs and impacts of the donor and receiving basins together.

The agency’s donor basin analysis, filed earlier this year, doesn’t specifically name any additional communities it plans to bring into its system. But Stephen Estes-Smargiassi, MWRA’s interim executive director, said in an interview that Weymouth and Wayland are currently going through the process to receive water and join the agency’s network, with more to come.

“We do want to provide water to additional communities that are in need of water, either for growth to allow more new housing, or because their existing supplies have become contaminated, and they’re looking for a way to resolve that in an efficient way,” he said. “This mechanism streamlines the process for our half of the analysis.”

But the Quabbin communities are already on edge from the MWRA’s handling of the drought and suffer from glaringly low state compensation for land they can’t develop – and can’t tax – in order to protect a water source they don’t drink from. The towns that guard Greater Boston’s water supply, and therefore hold the keys to any economic development poised to occur there, are facing dire fiscal constraints, cutting public school workers, consolidating emergency services, and dealing with local water crises of their own that render municipal buildings unusable.

To them, the MWRA’s maneuver feels more like an ill-considered end-around than a genuine effort to reduce inefficient red tape.

In fact, if state officials permit the MWRA’s plan, it would have the “functional effect of rewriting the law and sidestepping the fundamental purpose” of the Interbasin Transfer Act, wrote Comerford, Sen. Jake Oliveira, and Reps. Aaron Saunders and Susannah Whipps, who represent towns around the Quabbin, in a letter to the Water Resources Commission.

“Approving the application would create exactly what the Act was designed to prevent: extraction authority untethered from proven necessity,” the lawmakers wrote.

The debate is injecting new life into a simmering debate on Beacon Hill.

House Speaker Ron Mariano has long sought to expand MWRA’s service territory, particularly to include municipalities along the South Shore that he represents, only to stall out in the Senate.

Meanwhile, pending legislation would grant the Quabbin communities a permanent seat on the MWRA board and ramp up payments to those towns.

Gov. Maura Healey sided with the Quabbin communities’ concerns this summer, urging the MWRA in a letter to meet their “pressing needs.” In response, Estes-Smargiassi said his agency began helping Belchertown explore the feasibility of new drinking water wells — discussions that the town’s water district confirmed took place but said the project is unlikely to move forward.

Healey’s move to wade into the dispute further complicates the picture as it relates to the MWRA’s proposal, given that the agency argues the move will be necessary to meet ambitious state housing goals and new development opportunities like a former naval site in Weymouth, a top priority for the governor.

“This is one of those classic cases where two good, valid public policies are coming up against each other,” said Martin Pillsbury, senior environmental adviser at the Metropolitan Area Planning Council, who previously served on multiple water management task forces.

The MWRA maintains that, even with demand growth in its existing service area and the potential expansion into new communities, there is more than enough water in the Quabbin to justify the large new withdrawals.

The current average annual demand of approximately 200 million gallons of water per day — considerably below previous levels thanks to more efficient appliances and conservation measures adopted by the MWRA — leaves plenty of room before hitting the reservoir’s cap of 300 million gallons per day, according to the agency’s donor basin analysis.

But those numbers obscure the reality, said Lexi Dewey, the former head of the MWRA’s water supply citizens advisory committee, who argued that the MWRA is overselling how much extra water capacity it has available.

At various points this past summer, daily withdrawals of the Quabbin hovered around and even exceeded 300 million gallons per day, according to agency records reviewed by CommonWealth Beacon.

Asking state officials to further deplete the Quabbin by approving withdrawal of an additional 20 million gallons of water per day without identifying any specific new communities amounts to a “serious disregard” for the intent of the law, Dewey said.

“I’m very worried that the Water Resources Commission is going to let this go by, and there is no way that should be allowed to happen,” she said. “You don’t get to come back and appeal. If they vote for this, it’s final and it’s forever.”