RIVIERA BEACH — The city council voted unanimously Wednesday night to contribute up to $7 million toward an ocean breakwater designed to reduce beach erosion on Singer Island.

The vote came in a packed council chambers after some mainland residents complained that they should not have to help pay for shoreline protection on the barrier island.

Councilwoman Judy Davis urged all to view the city's needs as a whole and to move beyond the east-side, west-side rift that has divided some residents in the past.

"That beach belongs to all of us," Davis said. "Let's move our city forward in a positive way."

Assistant City Manager Paul White said the city has spent $15 million over the past four years on improvements to recreation facilities on the mainland.

Council Chairman Cedrick Thomas said the city would pass a bond issue large enough that additional money will be available for mainland projects.

The city's contribution to the breakwater is expected to be $6 million - 20 percent of the $30 million estimated total cost. If construction costs exceed the estimate, the city could be asked to contribute up to $1 million more with council approval. The agreement calls for Palm Beach County to contribute $12.5 million. Another $11.5 million will come from the state.

As designed, the breakwater will run parallel to the beach for a mile, from the south end of John D. MacArthur Beach State Park to Ocean Reef Park.

It will consist of 11 wave-breaking structures made of limestone and granite that rise 1 to 3 feet above the surface in about 12 feet of water. Gaps will allow swimmers, sea turtles and water to move through.

Although the breakwater is not expected to stop all beach erosion, it should slow erosion enough that only sand from upland sources will be needed to maintain beaches behind the breakwater, said Daniel Bates, the county's environmental director. "We'd be saving a lot of offshore dredging work," he said.

Beach restoration projects that involve pumping sand from offshore typically cost around $8 million and must be done every seven years or so, Bates said.

The project is expected to create 6 acres of hard-bottom habitat along the ocean floor.

If the county approves the project and permits are secured as expected, breakwater construction would begin this summer, Bates said. Similar breakwaters are being considered for the waters south of Jupiter Inlet and off Lantana Beach.

Also on Wednesday, the council unanimously approved the site plan for Florida Power & Light Co.'s conversion of its old Riviera Beach power plant to natural gas.

The power plant conversion, expected to be complete in 2014, would more than double the plant's generating capacity, to 1,250 megawatts. Smoke stacks of the new plant will be 157 feet tall, just over half the height of the existing 300-foot stacks.