Florida Gov. Rick Scott added two more counties on Thursday to the state of emergency declared over a "guacamole-thick" algae bloom affecting a stretch of beaches promoted as the state's "Treasure Coast."

Scott signed the amended executive order to add adding Lee and Palm Beach counties to Wednesday's emergency declaration for Martin and St. Lucie counties. Palm Beach County is directly south of the existing emergency area, while Lee County is on Florida's Gulf coast.

The blue-green algae is the latest contaminant featured in arguments stretching over years involving water flowing from Lake Okeechobee, which is critical to South Florida's water supply and flood control systems.

At Central Marine boat docks in Stuart on Thursday, pea-green and brown algae coated the water and smelled strongly like cow manure. Blooms that started last week in the St. Lucie River continue to spread, threatening Atlantic beaches expecting crowds of families for the holiday weekend.

Sarah Chaney, a receptionist at Central Marine, told the Associated Press that boaters and fisherman are canceling reservations after seeing reports of the algae, which she called "horrible and disgusting."

"I would describe them as guacamole-thick. And it stinks," said Gabriella Ferrero, spokeswoman for Martin County.

Chris Mascia Palas, a resident of Stuart, Fla., posted videos to her Facebook showing manatees struggling to get through the thick algae in a canal behind their house.

“The water is like thick pea soup and has blue color in it as well. It stinks like a dead rotting something! .. (The manatee was) clearly was in search of fresh water as well as struggling to clear its airways,” she wrote.

Florida's U.S. senators, Republican Marco Rubio and Democrat Bill Nelson, have joined Martin County commissioners in calling for the Army Corps of Engineers to stop the flow of water between the river and Lake Okeechobee. Residents and business owners blame the algae on pollutants streaming from the lake.

After touring the St. Lucie River as it passes through downtown Stuart, Nelson said the problems can be traced to Florida's history of diverting water to the ocean.

"We need to repair 75 years of diking and draining, but that takes time," he said. He called on the Florida Legislature to spend money approved by state voters for environmental projects such as purchasing land around Lake Okeechobee for water storage instead of diverting the funds to pay for administrative costs. Rubio is scheduled to visit the area Friday.

When Scott declared a state emergency for the area Wednesday, he blamed the federal government for neglecting repairs to the lake's aging dike that's considered one of the country's most at-risk for imminent failure.

Some residents blamed Scott instead on Thursday. He hasn't done enough to curb pollution from farms north of the lake or purchase land farther south where lake waters could be stored and cleaned, said Irene Gomes, owner of the Driftwood Motel in Jensen Beach.

The algae has rapidly grown from a beach nuisance to a health concern, as one customer made plans to leave early if the algae triggered breathing issues, said Gomes, whose family has owned the motel's turquoise-colored cabins since 1958.

"At one point, I could say to my customers, 'Come down, it's not at all the beaches,' because it wasn't toxic. Now we're talking about health issues," Gomes said.

Chaney, the Central Marine receptionist, said Scott should visit the area, even if he gets criticized.

"He needs to come see it himself and stop being a coward," she said.

Lake Okeechobee is the largest in Florida and the second largest body of freshwater in the contiguous United States. Flooding there after a major hurricane in 1928 killed at least 2,500 people in surrounding communities of mostly poor, black farmworkers. It inspired the storm central to Zora Neale Hurston's novel "Their Eyes Were Watching God."

To reduce the risk of a breach in the dike built after that hurricane, the U.S. Army Corps of Engineers tries to keep lake water levels between 12.5 feet and 15.5 feet above sea level. Shoring up the dike will take years. In the meantime freshwater is released east and west of the lake into the Caloosahatchee and St. Lucie rivers.

State water managers have said local stormwater runoff and septic tanks also fuel algae blooms. They're working to direct more water south of Lake Okeechobee into the parched Everglades, but federal regulations, conservation mandates and stalled restoration projects complicate those efforts.

In neighboring St. Lucie County, home to the troubled Indian River Lagoon, officials have prohibited homeowners from using fertilizer during the summer and begun working with the state to test waterways for pollution that might be linked to septic tanks.

"A lot of people want to blame Lake Okeechobee, it's an easy target, but there are a lot of factors that contribute to the health of the lagoon," said St. Lucie County spokesman Erick Gill.

Murky waters on southwest Florida's Gulf Coast also are blamed on the lake's discharges. Fort Myers-area lawmakers said Thursday that Scott should extend the state of emergency to Lee County because of water issues in the Caloosahatchee River.

The Associated Press contributed to this report.

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