Florida's toxic algae is damaging more than the coastline — it's destroying the local economy, too.
In a region that relies heavily on tourism, the giant sludgy green froth currently plaguing Florida's "Treasure Coast" is a business owner's nightmare.
"Obviously the headlines that say, 'South Florida covered in green algae' have an impact in a negative way," said Erick Gill, public information officer for Saint Lucie County.
Though beach closures in the county have been minimal, "There is that perception," he said.
Florida Governor Rick Scott declared a state of emergency for St. Lucie and Martin counties on June 29, and added Lee and Palm Beach counties the following day. Coming just before the July 4th holiday weekend, the news dealt a blow to hotels and tourism-related businesses across the area.
Hotel occupancy rates in the West Palm Beach and Boca Raton areas for the holiday weekend fell as much as 18 percent from a year earlier, according to data from hospitality research company STR.
"The absolute numbers aren't bad, but it's off a lot from where it was," said Bobby Bowers, STR's senior vice president of operations, saying concerns about foul water probably deterred some would-be visitors over Independence Day weekend.
Palm Beach County tourism officials say they're already doing damage control.
"Our visitors information centers have received a number of calls asking, 'Is the algae bloom prevalent in Palm Beach County?'" said Jorge Pesquera, president and CEO of Discover The Palm Beaches, the county's tourism marketing organization. "There have been a number of cancellations at the hotel level."
The problem isn't just limited to lodging. Industries such as fishing and boating — chartering boats and recreational sport-fishing are both popular in the area — have also been affected, as have retail and restaurant operators.
"All of these businesses have indicated economic damage," said Morgan McCord, a spokesperson for the Florida Department of Economic Opportunity, in an email to NBC News.
Once a state of emergency was declared, the DEO surveyed business owners about the impact. Since then, "We have received nearly 40 survey responses from locally affected businesses," said McCord.
More are likely to join them. Earlier this year, nearly 150 businesses in Lee, Martin and St. Lucie counties filed with the department to claim physical or financial damage after another crisis involving Lake Okeechobee water discharge, McCord said.
"In-shore activities are most affected, as well as waterfront dining," Michele Miller, director of operations at the Marine Industries Association of the Treasure Coast, said via email.
"Charter fishing is OK because they can go offshore to clean water," she said, adding that fuel retailers at marinas were also seeing a falloff in business.
"We have some anecdotal information about the water sports providers getting a number of calls and also seeing certain reduction in their business levels," Pesquera said.
"I think there's going to be a certain percentage of travelers who are going to look at it and say — just the fact that it's there at all — say 'I don't want to risk that,'" Bowers said.
There are concerns that this malaise affecting tourism even could spill over into the residential real estate market. Local NBC News affiliate WPTV reported that some potential buyers of vacation property were getting cold feet at the prospect of not being able to dunk their toes in the water. In a 2015 study, trade group Florida Realtors found that, although an individual algae bloom doesn't depress housing prices, the effect is cumulative.
"While the algal blooms and water discharge events have caused distress to home prices, for the most part, individual events have not affected homebuyers' opinions of homes," the report found, but it also noted that ongoing water quality issues affect what buyers are willing to pay.
Local business owners, especially those with ties to tourism, are worried how the rest of the summer is going to shape up.
"If the problem is not fixed and keeps getting worse and they close more and more beaches, it will definitely take a toll," said Heather Lowenthal, owner of Palm Beach wedding-planning firm Posh Parties.
"When people who don't live here are using South Florida as a destination for their event and want to spend the weekend at the beach, I'm sure it will be something to consider."