Spoil Islands of the Indian River Lagoon off Sebastian

The spoil islands off Sebastian are human-made mounds of Intracoastal Waterway dredge material that now carry mangroves, pines and nesting birds in the Indian River Lagoon.

Every island in the chain off the Sebastian riverfront was pumped up from the channel bottom. Florida DEP says the deposited material consists of sand, shell, muck and limestone rubble (Florida DEP). The islands sit inside the Indian River-Malabar to Vero Beach Aquatic Preserve, a 28,000-acre preserve in Brevard and Indian River counties that the state designated in 1970.

DEP does not class them as a natural community, yet it says spoil islands hold most of the bird rookeries in the Indian River Lagoon Aquatic Preserve system (Florida DEP). The UF/IFAS Florida Medical Entomology Laboratory in Vero Beach puts it the same way, calling them home to some of the most important rookeries in the lagoon (UF/IFAS FMEL). Last verified: October 14, 2026, on the Florida DEP, UF/IFAS, Indian River County and Florida Inland Navigation District websites.

Most spoil islands near Sebastian date from Atlantic Intracoastal Waterway dredging between 1951 and 1961, according to the UF/IFAS Florida Medical Entomology Laboratory.

The FMEL summary adds that islands in Mosquito Lagoon, far north of Sebastian, came instead from dredging for the Canaveral and Saturn Barge Canals (UF/IFAS FMEL). In the Sebastian reach the source is the waterway itself, which the 1986 state management plan says extends the entire length of the aquatic preserve (1986 preserve plan).

The 1986 plan says the spoil islands were conveyed to the Florida Inland Navigation District (FIND) for navigational improvement and have been dedicated to recreation and waterbird roosting and nesting habitat (1986 preserve plan). FIND started a long-term dredged material management program in 1986 to build permanent sites for material dredged from the 398 miles of the Intracoastal Waterway between Nassau and Miami-Dade counties (FIND).

Indian River County has 55 spoil islands by the UF/IFAS FMEL count, and the 1986 state plan counted approximately 55 in the aquatic preserve that runs past Sebastian.

The counts come from the FMEL spoil island page, which also gives island sizes from less than 1.2 acres to more than 7.5 acres. The 1986 preserve management plan covers a different slice, Malabar south to Vero Beach, and notes that some of its islands had already eroded to shoals.

The figures differ because each source draws a different line on the map, and neither is recent. The FMEL page does not date its county counts, and the most detailed count for the Sebastian stretch is the 1986 plan, so any island lost to storms since then is not reflected in either number.

The spoil islands near Sebastian carry a mix of exotic trees inland and mangrove, salt marsh and seagrass at the edges, plus some of the lagoon's busiest bird rookeries.

Brazilian pepper and Australian pine make up much of the vegetation, according to Florida DEP, while mangrove forest, salt marsh and seagrass beds have colonized the shallow fringes. A 1990 Florida Department of Natural Resources survey listed 467 species of animals and plants on the lagoon's spoil islands, about 205 of them animals, from crabs and shrimp to fish, birds and mammals (UF/IFAS FMEL). Native plants on the islands include cabbage palm, gumbo limbo, wax myrtle, live oak and strangler fig, and FMEL notes that species diversity and vegetation cover increase from north to south along the lagoon.

Salt water shapes the Sebastian islands more than those up the lagoon. The 1986 plan records salinities of 30 to 36 parts per thousand at Sebastian against 20 to 26 near Malabar, because Sebastian Inlet is the only opening to the ocean in this area (1986 preserve plan). Several islands near Sebastian lie inside Pelican Island National Wildlife Refuge, created in 1903, which the U.S. Fish and Wildlife Service says provides feeding, nesting and roosting areas for over 130 species of birds.

Most spoil islands off Sebastian belong to the State of Florida, with others held by federal agencies, local governments and private owners, and each state island carries a best use designation.

UF/IFAS FMEL lists the designations used in state management plans: conservation, passive recreation, education, active recreation, and combinations of these. The 1986 preserve plan set the goal of managing state-owned spoil islands in the Sebastian preserve as bird rookeries and wildlife habitat areas.

Indian River County shows how a local government takes on an island. Boat Club Island, listed as Spoil Island IR-25, lies west of the Intracoastal Waterway about 110 meters northwest of Channel Marker 120 and is owned by the state Board of Trustees of the Internal Improvement Trust Fund (Indian River County). The county signed a 10-year agreement with the state in 1996 to manage its facilities and in March 2010 took a sovereignty submerged lands lease on the southern part for public recreation. The posted rules are no alcohol, no hunting and primitive camping for no more than 3 days, and the island is open 24/7 with 2 docks.

Money for that kind of work comes partly from FIND. Its Small-Scale Spoil Island Restoration and Enhancement program caps awards at $20,000 per project and $60,000 per county per fiscal year, and it requires applicants such as Indian River County or the City of Sebastian to hold at least a five-year lease or management agreement with the island's government owner. Eligible work includes exotic plant removal, trash management, signage and camping, fishing, docking and mooring improvements.

Restoration on the lagoon spoil islands has ranged from the 2001 BC 48 replanting recorded by NOAA's Community-based Restoration Program to the volunteer cleanups Florida DEP runs today.

The NOAA Restoration Center records the Spoil Island BC 48 project in Brevard County, north of Sebastian, which began in July 2001 with the Sebastian Inlet Sportfishing Association as partner. Some 30 volunteers pulled invasive exotics and planted natives, creating and restoring two acres of mangrove habitat and seven acres of upland habitat with an interpretive trail about the lagoon.

Florida DEP lists beach and spoil island cleanups among the preserve's volunteer opportunities and names its conservation work as protecting bird nesting areas, planting mangroves, oyster reef restoration and seagrass surveys. Volunteers can contact [email protected], and DEP names the Environmental Learning Center and the Marine Resources Council as partner groups.

The spoil islands near Sebastian are reached only by boat or kayak, most directly from the Main Street Boat Ramp at Main Street and Indian River Drive.

The City of Sebastian lists Main Street Park and Boat Ramp at 1300 Indian River Drive, just east of U.S. Highway 1, with trailer parking and restrooms. Florida DEP lists the same ramp among the preserve's access points, charges no fee to visit the preserve and takes donations through Friends of the Spoil Islands, which it names as the place to check for visiting and camping information. The Sebastian spoil island camping guide covers which islands allow tents.

Two DEP rules matter on the way out. DEP warns that seagrass is protected in aquatic preserves and that damaging it can bring a fine of up to $1,000, so boaters crossing the flats off Indian River Drive trim up over the grass. Pets are allowed, but DEP asks owners not to let them run free near nesting birds and to pick up after them. Kayaking and boating are allowed in the lagoon waters around the refuge islands, according to the U.S. Fish and Wildlife Service.