Aerial photos of stormwater flowing into the ocean are sparking concerns on the Treasure Coast.

The photos were taken Saturday and show a large, dark plume of murky freshwater along Jupiter Island south of the St. Lucie Inlet.

"It was really, really massive," photographer Cam Collins said. "It had to have been at least 10 miles."

The freshwater is not from Lake Okeechobee, but rather stormwater runoff, according to the South Florida Water Management District.

Heavy rain over the past two months in Martin and St. Lucie counties has left water building up in canals, and the Army Corps of Engineers started discharging the runoff into the St. Lucie River to prevent flooding.

While the discharges are a common flood control operation during the rainy season, experts at the Florida Oceanographic Society are worried that too much freshwater over too long a duration could damage reefs.

“It blocks the sunlight and then [the reefs] don’t grow, and they can die pretty quickly,” Florida Oceanographic Society Executive Director Mark Perry said. “If it’s just for a short duration, the [reefs] can recover, but if it’s a long duration ... it’s going to start to die off, and we’ve seen that now for several weeks.”

Of particular concern is the St. Lucie Inlet State Park reef. Perry said his organization will most likely have divers survey for any damage once the water clears up.