At first pass, there seems little amiss in the idyll of Florida Bay. A wedge-shaped expanse of water between the Everglades and the Florida Keys, it is a clean, sun-dappled 1,000 sq mile playground for reddening tourists, grizzled fishermen and loud-shirted locals.

But the consequences of Florida’s century-long attempt to bend the environment to its will aren’t hard to find. Starved of fresh water from a reworking of its natural plumbing further north and menaced by seas rising due to climate change, the Everglades and its adjoining bay are teetering at the edge of existential crisis.

“The patient is on life support at the moment,” said Steve Davis, senior ecologist at conservation not-for-profit Everglades Foundation, describing what was once a prime fishing area in the western portion of the bay.

A severe slump in rainfall in 2015 meant salinity levels rocketed in the bay, with the water becoming twice as salty in the ocean. This led to the die-off of seagrass, crucial for local marine life, leaving the water matted with deceased vegetation.

This area, just last year smelled like death. It smelled like rotten eggs for almost three months

The water here is shallow but still impenetrably murky, with the odd strand of seagrass floating by. Hurricane Irma tore up much of what remained last year, uprooting mangroves that had managed to survive the surging salt.

“Notice how turbid and brown the water is,” Davis said, standing up on his skiff and peering into the bay. “This area, just last year smelled like death. It smelled like rotten eggs for almost three months.” Shark Bight, a cove found further north off the Everglades, is a prime birdwatching and fishing paradise turned “mud pit”, Davis said.

Eddie Yarborough, a leathery fishing guide who has spent the last 25 years traversing the bay for trout, redfish and snook, likens the water to “chocolate milk”. Yarborough morosely added: “The water used to be so clear you could see the seagrass move back and forth. Now you can’t see the bottom. The dead water sort of moves around the bay and you think ‘I’ve just gotta get out of here.’”

Steve Davis, the senior ecologist at the Everglades Foundation. Photograph: Everglades Foundation

Decades of often poisonous politics have pushed the Everglades, one of the largest and perhaps best-known wetlands in the world, down the path of entropy and potential collapse. A sweeping plan to restore the Everglades was passed by Congress in 2000 and promptly stalled.

Now less than half of its original size, the Everglades is beset by encroaching development and nutrient pollution and riddled with invasive species, such as the Burmese python, and exotic plants, such as Brazilian pepper and Australian pine.

But conservationists have fresh hope in the unlikely corporeal form of Ron DeSantis, the new Republican governor of Florida who roused national attention with a campaign video that vowed his children’s fealty to Donald Trump and a televised debate where his opponent, Democrat Andrew Gillum, accused his supporters of racism.

Since taking office in January, DeSantis has taken an unTrumpian approach to the environment, outlining a $2.5bn plan over four years to rescue the ailing Everglades. The plan would tackle local water pollution, protect springs and finish raising the Tamiami Trail, a highway that links Miami and Florida’s west coast by cutting across the Everglades, to allow water to flow south to the ecosystem.

DeSantis has called for the resignations of the entire South Florida Water Management District board, which controls water policy for the region, and has appointed two members – Ron “Alligator Ron” Bergeron and Chauncey Goss – who both have strong green credentials. Florida has even thrown itself into a legal battle to halt a controversial oil drilling project in the north-eastern reaches of the Everglades.

“Our water and natural resources are the foundation of our economy and our way of life in Florida,” DeSantis said. “The protection of water resources is one of the most pressing issues facing our state.” Environmentalists have been cheered by the contrast from the previous governor, Rick Scott, who cut funding for environmental programs. DeSantis isn’t exactly a global warming warrior – he prefers “Teddy Roosevelt conservationist” – but he will at least utter the words “climate change”, unlike Scott, who reportedly banned the term.

Ron DeSantis with his wife Casey. DeSantis has outlined a major plan to rescue the Everglades. Photograph: Kevin Lamarque/Reuters

“It feels like more has happened in the past few months than in the past 25 years,” said Eric Eikenberg, the chief executive of the Everglades Foundation.

The problems faced by the Everglades aren’t new or unexplored. Not long after developers started draining the wetlands for agriculture and paved it over for roads and houses, the effects started rippling through the system.

By the 1960s, scientists had calculated that while around 2m acre feet (2.5bn cubic metres) of water once flowed in a shallow river of grass from central Florida to the state’s southern tip, the volume of this conveyor belt had been cut in half.

There was a large outcry ... we have got some momentum now Rene Price, hydrology expert

The Everglades’ link to its headwater in Lake Okeechobee has been severed, with water diverted via canals for agriculture, particularly sugar. Without the nourishing freshwater, the ecosystem further south has become saltier and prone to disastrous events, such as happened in 2015, when pristine water turns into a muddy slush, causing fish to flee or die. The region is again in mild drought, meaning that rainwater isn’t currently coming to the Everglades’ salvation.

“The problem is we’re just not getting enough water,” Davis said. “We only get about a third of the water in the eastern Florida Bay that we received historically. A national park, a world heritage site, an international biosphere reserve, and we’re starving it of fresh water.”

One solution, Davis and other advocates believe, is to create a vast reservoir south of Lake Okeechobee that would store water intended for the Everglades. The water would filter south through a system of marshes to deliver millions of gallons of replenishment to the ecosystem. DeSantis backed the plan and recently penned a letter to Trump, alongside Florida senators Scott and Marco Rubio, to ask for funding.

There is political expediency in altering the current scenario where the water in Lake Okeechobee is discharged to the west and east, via the Caloosahatchee and the St Lucie rivers respectively, when it fills up and threatens to overflow. Laden with chemicals from nearby agriculture and warmed in temperatures that are climbing as the climate heats up, the water is the perfect spawning ground for toxic blue-green algal blooms.

Dead fish in Florida following the 2018 toxic ‘red tide’. Photograph: Joe Raedle/Getty Images

Separate “red tide” algal outbreaks in the ocean ravaged Florida last year, leading to beaches being closed, horrified dog owners who saw their pets poisoned, and hundreds of tons of dead fish and manatees piling up along the Gulf coast.

The tourism industry, worth about $67bn annually to Florida, trembled. The breakdown of the natural chain of life was so starkly apparent to Floridians that it became a battleground in the midterm elections.

“Voters got hyped up about red tide and said ‘we want the government to act,’” said Rene Price, an expert in the hydrology of the Everglades at Florida International University. “There was a large outcry and it seems like we have got some momentum now.”

The Everglades faces the threat of salty inundation on all sides, with the sea level at its edge rising by about 5in since 2001. Price said this accelerating climate trend, driven by the melting of glaciers and expanding sea water, will see the Everglades retreat further north. There will be miles and miles of new Florida Bay.

“But we shouldn’t be sitting on our hands,” Price said. “We have the capability to stem the tide by increasing the flow of fresh water. This isn’t the time to give up.”