BRADENTON – Longboat Key and Manatee County officials plan to talk more frequently about issues affecting the islands on both sides of Longboat Pass since their joint work session last week.
Shared challenges for Anna Maria Island and Longboat Key include beach erosion and renourishment, dredging, and what to do about Beer Can Island.
Beer Can Island
Longboat Key wants Manatee County to pitch in to clean up Beer Can Island, officially called Greer Island, and offer emergency medical and police services at the Manatee County-owned park.
Shifting sands in Longboat Pass have caused Greer Island – actually a peninsula on the north end of Longboat Key – to spread under the Longboat Pass bridge and out the other side, making a popular shady spot under the bridge for boaters.
But those boaters sometimes violate Manatee County ordinances prohibiting alcohol, littering and dogs on the beach, according to Longboat Key’s Assistant to the Town Manager, Susan Phillips.
Residents of north Longboat Key, who also are Manatee County residents, and Longboat Key town staff have been cleaning the park, she said, with the town’s marine patrol responding to emergencies, she said.
Manatee County’s marine patrol also has responded to emergencies, said Charlie Hunsicker, the county’s Parks and Natural Resources Department director.
The county is deed restricted from adding trails, bathrooms or picnic shelters to the park, but can step up to help clean the park, he said.
The erosion that is changing the shape of Beer Can Island also is threatening north Longboat Key homes, Phillips said. This is leading Longboat Key to call for Manatee County to help pay for groins to be built to protect the homes.
Longboat Key already has installed erosion control devices on town property to help protect residents on North Shore Road and those on the Gulf of Mexico, she said.
Hunsicker said he plans to meet with Longboat Key officials to address immediate erosion issues, which may or may not involve funding from Manatee County.
Some blame north Longboat Key’s erosion on work done to protect Anna Maria Island, such as the terminal erosion control groin built more than 50 years ago at the south end of Coquina Beach.
“Any hardened feature like that has an impact on adjacent land in Longboat Key, but they need that groin,” just as Longboat Key needs similar groins to protect the north end of its island, Phillips said.
The groin “keeps Anna Maria Island from going into the dredged channel,” Hunsicker said.
However, the groin is crumbling, and next year, “We’re going to remove the rock of ages and re-rock it,” keeping it the same size, he said.
Three similarly-dilapidated structures to the north on Cortez Beach on Anna Maria Island were replaced in 2016 and are functioning well, as expected, he said.
The three permeable, adjustable erosion control groins at Twin Piers (a third pier was added after the name stuck) protect Gulf Drive – a hurricane evacuation route – from stormwater erosion, he said. They are popular surfing and fishing spots.
The $7.8 million structures did not affect erosion on north Longboat Key, he said, noting that dredging done by Longboat Key in 1992-94 could have caused some of the town’s erosion problems.
Coquina Beach rocks
In between the terminal groin and Twin Piers are several rows of rock on Coquina Beach running perpendicular to the shoreline that were installed to curb erosion, but now are obstacles for lifeguards to get to beachgoers, Hunsicker said.
“In the next year, we are looking at the feasibility of addressing the 50-year-old rock groins at Coquina Beach,” he said.
Made of concrete walls containing rusting rebar and covered with rock buttresses, the structures are “a maintenance problem for us,” Hunsicker said.
They could be replaced with shorter versions of the three groins on Cortez Beach that would “substantially improve the visuals of Coquina Beach,” or a series of short, rock breakwaters 50-75 yards offshore, parallel to the beach and a foot above high tide.
“Beaches sometimes grow out to them,” he said.
Trying to find new ways to hold the beaches together, the county also has considered a system of undercurrent stabilizers, called geotubes, he said.
The system, developed by Dick Holmberg, is an alternative to beach renourishment, which is criticized for causing damage to fisheries at sand mining and dredge sites, disrupting nearshore marine life when the sand is dumped on the beach and bulldozed into the water to create a larger beach, and changing sea bottom contours, affecting currents and waves.
The smooth tubes, which are mostly buried in the sand perpendicular to the beach, extending into the water – similar to the placement of the rock groins on Cortez Beach – slow down the current like speed bumps, causing the current to drop the sand it is carrying, and building the beach.
It is designed as a one-time repair, as opposed to beach renourishment, which is a continual process.
“We’ve looked at variations of that for more than 10 years,” Hunsicker said. “The system addresses small areas of erosion, called ‘hot spots,’ on short distances of beach that are getting more erosion than adjacent areas due to underwater natural formations.”
While the system is effective in those cases, it would not be as effective as beach renourishment is on long stretches of beach like Anna Maria Island has, which erodes at roughly the same rate.
Manatee County does not have the resources to bring in large equipment to repair small areas of beach, he said.
“By the time we are fully mobilized for a large project, it wouldn’t contribute to the overall effectiveness of the project,” Hunsicker said.