IPSWICH — By the end of last summer, the dark waters of the Ipswich River no longer made it to the sea.

With the region gripped in historic drought, and millions of gallons of water siphoned away without restriction, the river ran dry. Millions of fish, insects, and other creatures died, and water actually flowed backward in some tributaries, sucked up by municipal wells.

With climate change expected to increase the frequency of droughts, state officials are preparing sweeping new restrictions to prevent future shortages in what would be among the most significant changes to water management in Massachusetts in decades and result in many municipalities, big businesses, and other major water users no longer being exempt from water restrictions.

“The current system is unfair and is one of the most egregious environmental issues in the state,’’ said Wayne Castonguay, executive director of the Ipswich River Watershed Association. “These steps are long overdue.’’

Since 1986, about 800 large water users — including the Massachusetts Water Resources Authority, scores of municipalities, cranberry bogs, farms, and golf courses — have been exempt from state conservation requirements, even during extreme droughts. The MWRA alone supplies water to about 45 percent of the state’s population, including Boston and 60 other communities.

As a result, residents in some towns can water their lawns or wash their cars as often as they like, while communities that are subject to state permits face strict limits or bans during drought conditions.

Towns such as Ipswich, for example, regularly issue a range of restrictions on water use, while others that tap into the river, such as Peabody, Lynn, and Salem, don’t. An estimated 60 percent of all the water used in Massachusetts is not subject to restrictions.

Those communities not required by the state to conserve water were granted exemptions in 1986, when the current system took shape, or received waivers afterward, with the state requiring only that they monitor their water use. They weren’t required to abide by state restrictions, so long as they didn’t use more water than they were allotted.

Those that did require more had to seek permits from the state, which came with a range of conservation requirements that have evolved over the years, including that they conserve water during droughts.

Many local officials and environmental advocates say the system is unfair and untenable, underscored by the recent succession of major droughts. Last summer’s dry spell came just four years after one of the region’s worst droughts on record.

“The state has resisted doing anything about the inequity of water withdrawals for too long,’’ said Julia Blatt, executive director of the Massachusetts Rivers Alliance. “We know it will only get worse in the future, so this is the moment to act.’’

Critics of the proposed rules say they could cause water rates to increase, burdening municipalities already coping with other expensive water-quality regulations. But state environmental officials said they are key to the state’s most recent Drought Management Plan, which anticipates the number of droughts — and their severity — will increase as the planet warms.

Underscoring the need for changes, the state’s Drought Management Task Force on March 12 took the rare step of declaring mild drought conditions in the Berkshires, at a time of year when flooding is usually the concern.

The proposed changes would require far more municipalities and others that use more than 100,000 gallons of water a day to abide by the same rules during droughts, though the state might still exempt those that submit their own drought management plans. The rules could take effect as soon as this year.

When the state declares a “mild’’ drought, the rules would limit nonessential water use — filling pools, activating sprinklers, washing cars — to one day a week between 5 p.m. and 9 a.m. During a “significant’’ drought, residents would be able to use water for similar purposes only with a hand-held hose or watering can. During a “critical’’ or “emergency’’ drought, all such nonessential outdoor water use would be banned.

The rules would be more flexible for golf courses, about 60 percent of which aren’t currently subject to state water restrictions. Golf courses would also be banned from watering during the day in droughts, except for hand-watering in certain locations. But they could continue to water tees and greens, until state officials declared a drought emergency — the most extreme designation — or the governor issued an emergency proclamation.

Baker administration officials declined to allow environmental officials to answer questions. In a statement, they said the changes would support the state’s efforts to address climate change.

The administration “is working closely with municipalities and public water suppliers to ensure the long-term water needs of Massachusetts residents are met, while supporting demand management, the conservation of water resources, and the protection of aquatic ecosystems,’’ said Craig Gilvarg, a spokesman for the state’s Executive Office of Energy and Environmental Affairs.

Water suppliers say the changes aren’t necessary and would likely increase costs, as those who pay higher rates by using more water effectively subsidize those who use less.

“Water is already underfunded, and people don’t want to pay more for their water,’’ said Jennifer A. Pederson, executive director of the Massachusetts Water Works Association, which represents municipal and private water suppliers throughout the state. She called the state’s proposal “a one-size-fits-all approach’’ that fails to account for different water systems’ capacity or needs and “broadly paints a brush of restrictions’’ that wouldn’t apply to private well owners.

Pederson said the rules come at a challenging time for water suppliers, which next month will be required by the state to start regularly testing for toxic chemicals known as PFAS. The costs of those tests, and new systems that can filter out the chemicals, can cost municipalities millions of dollars.

“We, too, are concerned about water resources and supply,’’ she said. “But we don’t think we need a statewide policy.’’

Officials at the MWRA, which could qualify for an exemption to the proposed rules because of its massive reservoirs, declined to comment.

Blatt and other environmental advocates said they were happy to see the state draft new regulations, though they consider them “baby steps’’ and urged more aggressive action.

“If you wait until you’re already in a drought to start conserving water, you’ve already waited too long, and you’re playing catch-up with water supplies and river health,’’ Blatt said.

In Ipswich, where the river is already significantly lower than usual for this time of year, local officials are again concerned about the water supply and aquatic ecosystems.

Last summer, when the latter portions of the river disappeared, everything from sunfish to redfin pickerel was wiped out. Many other fish and reptiles died. In 2016, the town was less than three weeks away from running out of water before rains returned, Castonguay said.

“We shouldn’t be the only ones having to require these common-sense steps,’’ he said.

David Abel can be reached at david.abel@globe.com. Follow him on Twitter @davabel.