STUART, Fla.: A smelly, “guacamole-thick” muck is fouling a stretch of beaches promoted as Florida’s “Treasure Coast,” where lawmakers and residents blame the federal government, saying the algae crisis is fueled by freshwater flows controlled by Army officials to protect an erosion-prone dike.

The blue-green algae is the latest contaminant featured in yearslong arguments over 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, pea-green and brown algae coated the water Thursday 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, said 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.

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.

In a news release Thursday afternoon, the Corps said it would begin reducing the flow from the lake Friday, targeting the Caloosahatchee Estuary and the St. Lucie Estuary.