Seawall Repair in Marathon, FL

Marathon spans a string of Middle Keys, including Knight's, Boot, Vaca, Fat Deer, and Grassy Key, from the east end of the Seven Mile Bridge at mile marker 47. The city incorporated in 1999, so local rules come from city hall, not Monroe County. Key Colony Beach sits in the middle of Marathon but is a separate municipality. Boot Key Harbor lies entirely inside city limits. Marathon jobs are run by our Key West seawall repair team, the Keys hub that schedules crews and filings up and down the island chain.

How Did Irma Hit Marathon's Waterfront?

Marathon took significant damage when Irma came ashore in 2017. The National Hurricane Center recorded a high-water mark of 3.72 feet above ground here, and 4 to 6 feet of inundation across the Middle and Upper Keys. Monroe County says more than 4,000 Keys homes were destroyed or badly damaged, mostly between Cudjoe Key and Marathon.

Monroe County counts 513 canals in the Keys and says every one was affected by Irma to some degree, with about 100,000 cubic yards of marine debris estimated across the chain. Walls on Marathon's canals took debris strikes, and their fill was soaked, then drained. Many still stand but have hollow ground behind the cap. Those hollows keep growing with every tide.

Which Permits Apply in Marathon?

Three layers usually come into play:

• City of Marathon: the city's Building Department issues the building permit for work inside city limits.
• Florida Keys National Marine Sanctuary: NOAA authorization and a benthic resource survey for shoreline work that may affect corals, along with valid FDEP, SFWMD, or Army Corps approvals.
• State: Fla. Stat. 403.813(1)(e) exempts restoring a wall at its previous location or within 18 inches waterward from a Chapter 403 permit.

If your property is in Key Colony Beach instead, that city's permit office applies. We confirm the jurisdiction from the parcel record first.

Which Repairs Suit Marathon Canal Walls?

• Void fill: NCFI-certified polyurethane injection fills hollows and seals leaking joints from the land side, with no in-water work near seagrass.
• Concrete work: our Key West bulkhead repair crew rebuilds spalled caps and cracked panels on Keys canals.
• Walls that moved: seawall reinforcement from Key West adds anchors to hold a leaning wall.

Is Marathon Under Monroe County Seawall Rules?

Not for local permits. Marathon writes its own. Unincorporated neighbors like Big Pine Key seawall repair and Key Largo seawall repair follow Monroe County's land development code. Up the chain, Islamorada seawall repair falls under another village's own code. The sanctuary's federal rules apply to all of them.

What Should Marathon Owners Check Each Season?

Walk the wall at a low tide and note:

• Soft ground or new holes behind the cap
• Gaps or rust stains at panel joints
• Cracks at dock tie-ins and cleats
• Silt washing out at the base

Take photos with a date stamp each time. A record of slow change helps us tell an old, stable crack from an active one, and it helps with insurance. Small signs now prevent a panel failure later. Request a free inspection or call 866-398-9323. Licensed in Florida (CBC1267322), serving FL, GA, and SC since 1996.