Miami-Dade County

Dry winter, slow progress on Everglades work puts Florida Bay at risk

Too little water and high salinity in Taylor Slough have scientists worried about the ecosystem in Florida Bay.
Too little water and high salinity in Taylor Slough have scientists worried about the ecosystem in Florida Bay. Miami Herald Staff

Florida Bay is thirsty, and it’s starting to bug the fish.

Last month, while the rest of the state fretted over polluted water from Lake Okeechobee fouling nearby rivers, officials at the South Florida Water Management District reported that the southern Everglades was in trouble.

Salinity in Taylor Slough, a historic freshwater artery for the bay, had spiked for the second year in a row, threatening to violate targets set to protect the marshes and marine life. A withering winter had left the region parched. And that could be bad news for shallow estuaries and creeks that fringe the bay.

Freshwater minnows, the first link in a complicated food chain, were not showing up in winter counts of fish stock. Last year, scientists counted a record low number of spotted sea trout, a fish perfectly engineered to reflect changes in the bay.

“What I think we’re seeing there is a direct response,” said Chris Kelble, an oceanographer with the National Oceanographic and Atmospheric Administration who studies the link between fish and the environment.

While spring rain is expected to drive down salinity in the short term, scientists fear the frequent swings from fresh to salt could be upsetting long-term stability and may hint that rising sea levels are trekking inland. Peat, the manna of Everglades marshes, could collapse. Coastal fringes that act as nurseries could become barren.

And the impacts would not just slam the ecosystem. A $7.6 billion recreational fishing industry could also be hurt. That includes an avid band of anglers who set their clocks by the annual spring migration of tarpon around the tip of Florida, synced precisely over millions of years to coincide with the wet season and freshwater that flowed from the north, University of Miami fisheries scientist Jerry Ault said.

“It’s an incredible choreography,” he said. “We’re putting the system into an imbalance that will play out over years, not just year to year.”

To keep the bay healthy, the South Florida Water Management District tries to balance flood control with water use and what the ecosystem needs to stay happy by setting minimum flow levels of freshwater, said Susan Gray, the district’s chief environmental scientist. Using models, they calculate how much freshwater is needed to keep units of salinity, called PSUs, in the right range: freshwater is 0 and ocean levels are 30.

But over the last two years, drought conditions have complicated that balance. Last month, for the first time, the district risked dropping below the required minimum flows for Taylor Slough. And for the second year in a row, the freshwater slough looked more like ocean water. Gauges in mangrove ponds have climbed up steadily from about 10 PSUs since the beginning of the year, while the amount of water in the slough has steadily dropped by more than half.

“We are not there yet, but we know we are very close,” Gray said last week.

Everglades restoration projects are intended to fix the problem. But so far, only one part of one of three critical projects aimed at increasing freshwater to the slough is working: the western half of the C-111 spreader canal.

The project was meant to undo decades of damage caused by the C-111 canal, a wide, long and deep canal dug in the 1960s. The canal completely upended the natural sheet flow of water across the Everglades by rerouting water from Taylor Slough — only a quarter of historic levels now move through the slough — to the drainage channel and out Barnes Sound. The spreader was supposed to suck water out of a nearby canal and allow it to flow more naturally. As with other restoration projects shared by the state and U.S. Army Corps of Engineers, work stalled.

To speed things up, the state took over and completed the western half of the spreader in 2012. (An eastern project remains unfinished.)

Within a year, the ecosystem started responding. Underwater plants flourished, increasing their cover by five times as much. Freshwater flows into Taylor Slough doubled.

But when two abnormally dry winters hit the region, Jerry Lorenz, Audubon Florida’s state director of research, said he realized the C-111 spreader couldn’t work without water from the north to supplement rainfall. It had nothing to spread.

“We need upstream water up and running for it to function properly,” he said.

But that piece of the puzzle is complicated. A suite of projects aimed at getting water moving through the Central Everglades stalled last year after the U.S. Corps of Engineers failed to send a report in time to Congress. And farmers to the east have also increasingly complained that the spreader is sending too much water into their fields rather than west into the Everglades, drowning crops.

“Right now we can’t move the water where we need to until the projects are complete,” Gray said. “We don’t have the capacity to move the water effectively.”

Scientists say they may already be seeing impacts from the high salinity in places. Since 2011 when the district last surveyed patches of Ruppia, a type of sea grass that once dominated the bay, Gray said coverage dropped from about 40 percent to 10 to 20 percent. In his winter fish survey, which he is now compiling, Lorenz said scientists found no freshwater fish. Last year, 40 percent of all the fish collected were freshwater, he said.

Data collected from Everglades National Park indicate some high and very high levels of salinity in the last two weeks, biological branch chief Tylan Dean said. But none of the levels are unprecedented, he said.

“There are enough signals... out there that many of us are concerned, so we’re watching the system closely to see what happens,” he said.

Salinity tends to be highest in the center of the wide shallow bay because it’s too far from currents off the Gulf of Mexico that keep water moving through the western bay. But crucial estuaries at the north end of the bay have historically been hardest hit because swings in salinity can destabilize habitat. If salt is too high, salt-tolerant plants will start to grow. But when salinity drops, they die.

“You never get a standing crop of aquatic vegetation and without that, you don’t get habitat for prey-based food,” Lorenz said.

In its natural state, water flowed into the bay across transverse glades. But those were typically the first places where flood control structures were built, Ault said. Everglades restoration is meant to undo that. But just delivering water isn’t enough, he said. It has to be clean.

“In the natural flow system, a water particle in Lake Okeechobee today would be out on the coral reef in less than 90 days,” he said.

So finding a place to store the water is critical, Lorenz said. Lorenz’s bosses and environmentalists are waging a bitter battle in Tallahassee to convince lawmakers and Gov. Rick Scott to use money from a constitutional amendment passed by voters in November to spend $10 billion over 20 years on environmental land.

A 2010 contract would allow the state to buy 46,000 acres of U.S. Sugar land. Of that, 26,000 acres south of the lake could be used for storage. Another 20,000 is too far west. A recent study by the University of Florida recommended the land be part of several storage solutions. But lawmakers opposed to the deal argue the state already owns too much land and Scott has said the state needs to finish the projects already started.

But of all the areas hit hard by damaging flood control measures, Everglades Foundation director of science and policy adviser Tom Van Lent said, Florida Bay may be most vulnerable.

“The bay is always on a kind of knife’s edge,” he said. “The single biggest input in the late dry season was this flow from the Everglades and it’s gone.”

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