LAKE WORTH, Fla. - A giant floating vacuum cleaner goes to work about once a year clearing out a buildup of sand that threatens to keep big ships from reaching the Port of Palm Beach.
With that work set to resume, the port and federal officials are also exploring deepening the Lake Worth Inlet in the future to lessen the frequency of the maintenance dredging and to potentially attract bigger ships to the port.
But the dredging poses a risk to endangered sea turtles and other marine life along the shore and within the Lake Worth Lagoon.
Port officials and the Army Corps of Engineers contend that the inlet deepening is still in the study phase. The corps says that maintenance dredging set to start this month, as well as any future dredging or deepening, will have to include sea turtle protections.
"We do not have a turtle issue," said Tim Murphy, the corps' project manager.
While the maintenance dredging of the inlet is needed to maintain navigation, the potential for deeper dredging raises environmental concerns, said Drew Martin of the Sierra Club.
"We should keep the dredging to a minimum," Martin said. "The deeper the inlet is dredged, the more problematic it's going to be."
The man-made Lake Worth Inlet is a vital navigation link between the Intracoastal Waterway and the Atlantic Ocean for weekend fishermen and cargo ships alike.
The problem is the inlet catches sand that the ocean naturally moves from north to south along Florida's east coast.
That buildup of sand has produced an 18-foot high shoal at the entrance to the inlet, which if allowed to grow would become an impediment to ship traffic, Murphy said.
"We need to keep the inlet open," port director Manuel Almira said. "Ships are getting bigger, not smaller."
Later this month, an Army Corps contractor is scheduled to start a $1.4 million project that calls for using a floating dredge with a long extending arm to vacuum sand out of the inlet.
Normally the sand would be piped onto nearby beaches south of the inlet to help combat erosion. But because it's too close to turtle nesting season, the corps plans to deposit the dredged sand in near-shore waters just south of the inlet.
Putting the sand near-shore in 17 feet of water, instead of dumping it deeper at sea, is intended to allow the natural movement of the ocean to gradually distribute the sand along the beaches.
That avoids disturbing turtles during nesting season and could still accomplish some beach nourishment, Murphy said.
The Sierra Club and the environmental group Surfrider support depositing the dredged sand in near-shore waters.
"If you put the sand back out at sea, it never finds its way back to shore," said Greg Lyon of Surfrider.
To offer additional turtle protections, the vacuuming arm of the dredge includes a built-in "turtle deflector" intended to block turtles that could otherwise get sucked in with the sand, Murphy said.
"We are abiding by the (U.S.) Fish and Wildlife Service recommendations and requirements," Murphy said.
Turtle concerns and safeguard requirements grow when considering deepening the inlet.
The Army Corps is considering in November deepening the inlet channel by about two feet, a move supported by the Port of Palm Beach.
"We are interested in going deeper," Almira said. "We have had to turn back some business … when they don't feel comfortable with the depth."
But more dredging poses a risk to sea turtles, said Martin, of the Sierra Club. A deeper inlet could also lead to stronger currents that stir up sediment, clouding water and posing a risk to reefs, Martin said.
Both the Army Corps and the U.S. Fish and Wildlife Service acknowledge that deepening the inlet "may affect" threatened and endangered sea turtles including: loggerheads, leatherbacks, hawksbill, green and Kemp's riley sea turtles, according to a Feb. 10 letter from the Fish and Wildlife Service.
In addition to the turtle protections required for collecting and distributing sand from the inlet, deeper dredging would require the Army Corps to come up with a plan to avoid "potential impacts to foraging and swimming sea turtles, and all other marine species under (federal) jurisdiction," according to the Fish and Wildlife Service.