February 12, 2018 07:01 AM
Updated February 13, 2018 10:04 AM
For years, South Florida water managers struggling to reverse the damage done to the Everglades by decades of flood control have done their best to replicate nature, timing the flow of water into marshes with the state’s wet and dry seasons.
But now researchers looking at 16 years worth of data say creeping sea rise is outpacing restoration efforts. And to save the marshes, they say, the strategy needs to change.
Sea rise “has been gaining momentum. It’s increasing at a faster rate since 2012,” said René Price, a Florida International University hydrogeologist and co-author of a new study that looks at the role rising seas play in restoration work. “So it’s almost imperative that it be considered now.”
Everglades restoration was supposed to fix the damage done by South Florida’s massive flood control system that began draining swampland in the late 1940s. But when a plan was drawn up in 2000 to send more water into marshes, Biscayne Bay and Florida Bay, it failed to anticipate the dramatic impacts of climate change. Rising sea levels have already started to fray the coastal fringe, with mangroves marching inland and freshwater sawgrass shrinking. It’s not unusual now to see small stands of saltwater mangroves popping up in marshes. As sawgrass dies, the peat built up over eons starts to collapse, lowering the ground level.
Scientists now believe the southern Everglades have reached a tipping point. What’s been less clear is which to blame: about five inches of sea rise since 2001 in the southern Everglades or prolonged damage from flood control.
“We wanted to know if this long-term data gave an indication of which was winning, sea level rise or water management. And we didn’t really know, although winning probably isn’t a good word,” said Price, a principal investigator for the Florida Coastal Everglades Long Term Ecological Research project.
What they found is sea rise is increasingly outpacing the flow of freshwater during the dry season. By the time spring rains arrive and the South Florida Water Management District begins moving more water south — the district monitors rainfall and typically begins flows about 10 weeks after the start of the wet season — it’s too late to reverse the damage.
Rather than use seasonal timing, the researchers say the district needs to look at water levels, and the difference between freshwater and saltwater.
“Basically the level of freshwater needs to be higher than sea level,” Price said. “They waited too long for the freshwater, and saltwater was allowed in during the early months of the rainy season. If you’re taking a freshwater wetland and adding salt, it’s not a good thing.”
The study comes at a time when the value of forests across the U.S., especially wetland forests capable of absorbing massive amounts of carbon, is being re-evaluated in terms of conservation. Mangroves in Everglades National Park alone provide between $2 billion and $3.4 billion worth of carbon storage. A recent assessment by the Dogwood Alliance, a North Carolina-based nonprofit that looked at economic factors like tourism, water supply and treatment and protection from extreme weather events like hurricanes, put the worth of Florida’s wetland forests at nearly $81 billion, more than any other state.
“It was sort of mind blowing … that the wetland forests in the south were worth $500 billion in service,” said author Sam Davis.
It also turns out that South Florida residents, and not just environmentalists, are willing to pay to save wetlands. Another FIU study, to be published in the journal Science of the Total Environment, surveyed more than 2,300 residents and found that when it came to the choice of restoring marshes or facing water restrictions, most were willing to pay an extra $18 a year for restoration work. If restoration included protecting endangered species, they agreed to pay even more.
“Benefits resonate more with the public because they can be linked to their well-being,” lead author Nadia Seeteram said in a statement.
Taking the public pulse on restoration efforts ongoing now for nearly two decades can also help combat restoration fatigue and push policymakers to stay the course, she said.
It’s not clear what changing operations to increase water flow south will take, and whether enough water exists. Last year, the National Academies of Science concluded in its annual review of restoration progress that far more freshwater is likely needed to make projects work. Plans to construct a massive reservoir also faltered, with the original proposal for 60,000 acres reduced to 17,000 acres.
District spokesman Randy Smith said in an email Friday that the agency is now reviewing the study.
“Since the study deals with water management operational implications, district scientists, policy specialists and water managers are currently reviewing it,” he said.
Price hopes they give it serious consideration.
“Definitely I think the district should take this to heart and think about changing their delivery schedule of freshwater into Everglades National Park and not be depending on a rainfall plan,” she said. “The timing of it needs to be spread throughout the year and not just in the wet season.”
Follow Jenny Staletovich on Twitter @jenstaletovich