State of the Inlet Reports — Sebastian, Florida

The State of the Inlet report measures how much sand sits in the reservoirs of Sebastian Inlet, how fast the 42-acre sand trap is filling, and how the inlet and about 6 miles of beach on either side are changing shape.

The Sebastian Inlet District report page describes it as a technical report that quantifies the volume of sand contained in inlet reservoirs, which helps set the district's sand bypassing budget for periodic dredging projects, and looks at morphological changes within the inlet system. It also identifies the infilling patterns of the sand trap, a 42-acre underwater basin that accumulates sand, and shoreline changes north and south of the inlet.

The district's Inlet Management Plan explainer, posted January 22, 2026, adds that the report calculates a Sebastian Inlet sediment budget and follows morphological changes along approximately 6 miles of beach shoreline north and south of the inlet. That stretch covers the beaches of Sebastian Inlet State Park and the Indian River County shore that receives bypassed sand.

Florida Tech's Dr. Gary Zarillo prepares the State of the Inlet report for the Sebastian Inlet District under a long-term monitoring agreement the district signed with the university in 2007.

The report page says that in 2007 the district entered a long-term coastal modeling agreement with Florida Tech's Ocean Engineering and Marine Sciences Department and Dr. Zarillo, to monitor sea level changes and natural sand transport and accumulation within the inlet system so that sand resources could be managed scientifically.

The instruments came first. The district explainer says Zarillo installed wave and weather gauges at Sebastian Inlet in 1993, and that the district has collected more data than any other inlet in Florida. Zarillo has more than 40 years of experience in coastal ocean processes, marine geology and sedimentology, according to the same page.

The partnership is public. Florida Tech's Coastal Processes Research Group describes its long-term monitoring program at Sebastian Inlet, led by Zarillo, with a north jetty weather station recording wind, air temperature and barometric pressure, and an offshore current profiler about 1,000 feet out measuring waves, currents and water level. The group publishes current conditions for Sebastian Inlet from data collected with the Sebastian Inlet District.

The district says its 2025 State of the Inlet report found the Sebastian Inlet sand budget still balanced when analyzed over 10-year intervals under the current sand management plan.

In its January 2026 explainer, the district wrote that sediment retained within the tidal inlet system is compensated by bypassing sand from the trap. In plain terms, the data indicate the Sebastian Inlet District is meeting its objective of placing sand onto downdrift beaches, together with its partner Indian River County, which also places sand on beaches south of the district's targeted area.

Sea level matters as much as storms. The same page says Zarillo's decades of data have revealed how seasonal sea level fluctuations influence sand volumes along the coastline. In his words, sea level is not the only factor in sand losses and gains on the Sebastian Inlet beaches; the flow of the Gulf Stream, storm impacts and even season changes play a part.

The findings feed a state plan. The Inlet Management Plan, established by the Florida Department of Environmental Protection in 2000 and updated in 2023, sets five strategies for Sebastian Inlet, beginning with regular beach and hydrographic surveys and including bypassing an annual average of 75,000 cubic yards of sand to the south beaches. The State of the Inlet report is how the district shows whether that target is being met.

The report tracks how full the Sebastian Inlet sand trap is, and the district dredges it when it fills to roughly 200,000 cubic yards, on average every 4 to 5 years.

The district FAQ says the district continuously monitors sand accumulation in the 42-acre sand trap and the navigation channel through its research partnership with Florida Tech and semi-annual bathymetric surveys of the entire inlet system and backwaters. Dredging and sand bypass projects follow as the trap fills to a capacity of about 200,000 cubic yards. The district's By the numbers page gives a slightly longer channel dredging interval, every 5 to 6 years, and lists the trap at 42 acres.

The latest cycle closed in 2026. The district projects page says the Sand Trap Dredging and Beach Placement Project was completed in April 2026, placing approximately 271,000 cubic yards on the south beach. The previous trap dredging, Phase I of the 2019 project, placed 113,000 cubic yards of sand on downdrift beaches south of Sebastian Inlet.

The surveys also serve boaters using Sebastian Inlet. The FAQ says the district posts its semi-annual bathymetric survey maps online as an aid to navigation, for a channel designed to be at least 150 feet wide and 9 feet deep.

The report matters to the beaches south of Sebastian Inlet because the state requires the district to pass sand around the inlet to them, and the report is the yardstick for how much has gone.

The Florida Department of Environmental Protection describes the Sebastian Inlet Management Plan as strategies for placing beach quality sand on the eroding beaches next to the inlet, meant to replicate the natural drift of sand that an inlet interrupts and to balance the inlet's sediment budget, consistent with section 161.142, Florida Statutes. The current plan was approved on November 9, 2023.

The district's notice of the plan says the department adopted it as a final order for Sebastian Inlet in Brevard and Indian River counties on November 9, 2023, replacing the previous plan adopted on March 16, 2000. Jetties stop the southward drift of sand, so the Indian River County beaches immediately south of the inlet, including Ambersand Beach, depend on what is bypassed.

The projects page shows where the sand lands. In 2023, the district completed a beach placement project spanning 1.5 miles between the area of the McLarty Treasure Museum and an area south of Ambersand Beach, and since 2008 it has secured $12.5 million in cost-share grants from the FDEP Beaches Funding Assistance Program for its projects.

The Sebastian Inlet District posts State of the Inlet reports for 2012, 2015 through 2025 (with 2015 to 2016 and 2017 to 2018 consolidated), and offers older copies by phone at (321) 724-5175.

The report page pairs the State of the Inlet series with a second series, the Sebastian Inlet District Wind, Wave and Weather Reports, drawn from the north jetty station and the two nearshore current profilers. It says the network's data serve a diverse audience, and that the profilers record currents, waves, water temperature and water level.

To discuss a report or request an older one, the page lists the district's number, (321) 724-5175. Last verified: October 10, 2026, on the Sebastian Inlet District website.