Marathon seawall repair and replacement
In Marathon, the city permits your seawall, not Monroe County, and its code treats a new vertical wall as a last resort. This guide covers Vaca Key, Boot Key Harbor, Knight Key and the Sombrero canals.
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Marathon: Vaca Key & Boot Key Harbor at a glance
- Who permits it
- City of Marathon Building Department
- Call first
- City of Marathon Building, (305) 289-5052
- The water
- 86 county-listed canals (169 to 271), most oceanside
- Storm record
- Wilma, 2005: about 5.8 ft above the average high tide at Vaca Key
- Local rule to know
- No new vertical seawalls on open water (Marathon code 106.36)
Get to know your waterfront
Marathon runs from the east end of the Seven Mile Bridge, about mile marker 47, to the Toms Harbor bridge near MM 60. Key Colony Beach, in the middle, is a separate city. Inside Marathon, the county lists 86 residential canals, 67 of them oceanside. Boot Key Harbor holds the City Marina at 800 35th Street.
City of Marathon Charter, Sec. 10 Land Description · Monroe County Residential Canals (Google Earth KMZ layer 'Residential_Canals_WGS', linked as 'Google Earth Document with Downloaded Canal Information') · Marina and Ports
Marathon seawall rules, canals and storm record
Marathon's code starts from no. Under LDR Sec. 106.36, a seawall on a residential canal is allowed only where riprap or a sloping rock revetment "will not suffice," as the City Biologist decides. Replacing a deteriorated wall is the classic case that qualifies. LDR Sec. 106.36
| Your situation | What the code says |
|---|---|
Failing wall on a canal | Replacement can qualify once the City Biologist agrees riprap will not do the job. |
Open-water lot with no wall | No new vertical seawalls or bulkheads on open water. |
Old wall on open water | Repair is exempt from the nonsubstantial-improvement cap but keeps the existing footprint. On unaltered shoreline it is allowed only if riprap with filter cloth is not feasible. |
Cap and yard | A cap up to 2 feet wide, and a swale, berm or curb of at least 6 inches directly behind the wall. |
Wall line | Set at average mean high water when permitted. Backfilling to reclaim eroded land is prohibited. |
Riprap | Boulders or clean rubble 6 inches to 3 feet across, landward of mangroves, no steeper than 2:1, reaching no more than 8 feet out. |
Sources: Marathon code 106.36 Marathon code 106.36 Marathon code 106.36 Marathon code 108.20
The code encourages riprap at the base of solid seawalls where it fits. Ask bidders to price that toe rock as its own line. See riprap and toe protection.
Marathon canals: find your number
The county inventory lists 86 canal polygons in Marathon, numbered 169 to 271, between mile markers 47 and 55. Most are oceanside, serving 2,975 parcels along roughly 91,000 feet of canal. Monroe County canal inventory
- Canals 251 to 268: Sombrero Beach Road and the Spanish-named streets off Sombrero Boulevard, such as Avenida Primiceria and Camino Real.
- Canals 172 to 201: Coco Plum Drive and Avenues A through O.
- Canals 169 and 170: Stirrup Key Boulevard and Windy Point Circle. Canal 171: Gulf of Mexico Boulevard. Canal 244: Palm Island Drive. county canal street list
Marathon runs its own canal program. It finished dredging canal 257, along Sombrero Beach Road, Man-O-War Road and Spoonbill Drive, and closed the project with DEP in April 2024. FloridaCommerce Keys oversight report county canal street list The county layer records three culverts on that canal. Monroe County canal inventory
The city also set aside more than $5.3 million for canal and culvert work in FY2023-24, with tidal culvert projects on canals 248/250, 245/246 and 186/191. FloridaCommerce Keys oversight report If your wall faces one of those canals, ask the city about timing before you pick a start date.
Wilma's record at Vaca Key
The daily tide is small here: about 1 foot at the bayside Vaca Key gauge, roughly half of Key West's range. NOAA Vaca Key datums Storms are another matter.
- Wilma set the gauge record on Oct. 24, 2005, at about 5.8 feet above mean higher high water (MHHW). NOAA Vaca Key datums
- The National Weather Service estimated storm tides of 5 to 8 feet above mean sea level, flooding U.S. 1, the airport and Keys Fisheries on Gulf View Avenue. NWS Key West Wilma summary
- The largest positive surge at Vaca Key from 1996 to 2018 was 75.2 inches, about double Key West's peak. county wind setup analysis
- Irma left a 3.7-foot high-water mark in Marathon. Hurricane Center Irma report
For a Marathon wall, that points to overtopping and lost backfill more than daily wear. Check the swale and the ground behind the cap after every storm. See soil loss behind a seawall.
Boot Key Harbor and the public waterfront
The City Marina sits at 800 35th Street, and the city notes its structures predate 1992. City of Marathon marina page After Irma, a 2019 recovery list proposed a new canal seawall there at $900,000. That was a request, not a bid. Marathon CDBG-DR marina list
Public numbers like these describe commercial walls. Use the seawall cost guide for a home budget.
Docks and lifts on a Marathon wall
- An existing or approved bulkhead may carry a parallel dock up to 8 feet wide. Marathon code 104.64
- Boat lifts may rise no more than 5 feet above the dock or seawall cap. Marathon code 104.64
- A dock needs minus 4 feet at mean low water at its end. Marathon code 104.64
- On a developed canal, mangroves are kept within 10 feet of mean high water or 20 percent of the canal width, whichever is less. Code Sec. 36-88
Plan dock and lift work with the wall: see docks and boat lifts.
What could the work cost?
Marathon charges $17.50 per $1,000 of contract price for seawalls, riprap and docks, with a $93.50 minimum, a $4 education fee and state surcharges. On an $80,000 contract the base fee is $1,400. The Building Official can revise a price not backed by a signed contract, so file the real number. For 30 days after a hurricane, only the minimum fee is due when the permit issues.
Calculator ranges come from a 2026 national cost guide and one Key West public bid. None is a quote; your written, itemized scope sets your price.
Compare quotes and plan a budget →Find the relevant permits and records
| Starting point | What to resolve | Prepare and look up |
|---|---|---|
City of Marathon Building Department | Building permits for seawall, riprap, dock and lift work anywhere in city limits, filed in the Viewpoint portal. | Parcel ID, proof of ownership and a signed contract. City Hall, 9805 Overseas Highway; (305) 289-5052; inspections (305) 289-4133. |
City of Marathon Planning (City Biologist) | Decides if riprap or a revetment will suffice before a vertical wall is approved, and reviews work in mangroves and shoreline buffers. | A natural resources inventory and, for docks on open water, a seafloor (benthic) survey. |
Florida DEP, Marathon branch | State exemption or permit, state submerged land and mangrove trimming. | Drawings of the existing and proposed wall line. (305) 289-7070. |
Army Corps, Keys Permits Section | Federal authorization; the city will not issue a dock permit until federal and state permits are in. | The same plan set sent to DEP. (305) 526-7181. |
Your Marathon seawall checklist
Work through these before you ask for bids on a Marathon wall.
Find your canal number
Look up your street in the county canal list or on the county canal map. The number tells you if a city canal or culvert project touches your water.
Canal, Roads Names and Areas (List of Keys Residential Canals by location) · Canal Restoration · Florida Keys Area of Critical State Concern Annual Report, FY23-24 (reporting period July 1, 2023 - June 30, 2024)
Pull your permit file
Search the city's Viewpoint portal for past seawall and dock permits at your address. Keep your parcel ID and proof of ownership handy, since the city asks for both.
Permit and Inspection Information · Building Frequently Asked Questions
Ask the riprap question first
Before an engineer draws a vertical wall, ask the city if riprap would suffice. The City Biologist decides, and the answer shapes the whole design.
Check the contractor's registration
Marathon requires contractors licensed by the state or county and registered with both the city and Monroe County. Confirm both before you sign.
Know the storm rule
Emergency repairs may start at once if the permit application reaches the Building Department within 48 hours, with an email to inspections@ci.marathon.fl.us.
Plan your Marathon seawall project
Tell us your canal or harbor, what you see at the cap and toe, and any storm damage. We will help you plan the next step and the questions to bring to the city.
Every answer here links to the public record behind it.
Marathon: Vaca Key & Boot Key Harbor project questions
Does Monroe County or the City of Marathon permit my seawall?
If your lot is inside Marathon, roughly mile marker 47 to 60 outside Key Colony Beach, the City of Marathon Building Department permits it. Call (305) 289-5052. Monroe County's office on Overseas Highway in Marathon handles unincorporated parcels, not city lots.
City of Marathon Charter, Sec. 10 Land Description · Building
Can I build a new seawall on open water in Marathon?
No. LDR Sec. 106.36 bars new vertical seawalls and bulkheads on open-water shorelines. An existing open-water wall can be repaired in its footprint, and on unaltered shoreline only if riprap with filter cloth is not feasible.
LDR Sec. 106.36 Criteria For Approval (Hardened Shorelines) · LDR Sec. 108.20 Nonconforming Docks And Shoreline Stabilization Structures
What does a Marathon seawall permit cost?
The city charges $17.50 per $1,000 of contract price, with a $93.50 minimum, plus a $4 education fee and state surcharges. For the first 30 days after a hurricane or tropical storm, only the minimum fee is due at issue and the rest waits until the permit closes.
Which inspections will a Marathon seawall job need?
The city's seawall and dock sequence runs Footings, Auger Tie Back, Wall or Cantilever, Deck, Davit Bases and Final. A permit goes void if no inspection passes for 180 days.
How high did Wilma push water at Vaca Key?
The Vaca Key gauge recorded about 5.8 feet above mean higher high water on Oct. 24, 2005, its highest reading. The Hurricane Center also cited a visual estimate near 9 feet in the Marathon area.
CO-OPS Metadata API: Vaca Key, FL (8723970) datums · Tropical Cyclone Report: Hurricane Wilma, 15-25 October 2005
Keep planning
Nearby waterfront guides
Key Colony Beach, Grassy Key, Crawl Key & Coco Plum (east Marathon), Duck Key
Show sourcesHide sources
- City of Marathon Charter, Sec. 10 Land DescriptionSource reviewed 2026-10-28
- Monroe County Residential Canals (Google Earth KMZ layer 'Residential_Canals_WGS', linked as 'Google Earth Document with Downloaded Canal Information')Source reviewed 2026-10-28
- Marina and PortsSource reviewed 2026-10-28
- LDR Sec. 106.36 Criteria For Approval (Hardened Shorelines)Source reviewed 2026-10-28
- LDR Sec. 108.20 Nonconforming Docks And Shoreline Stabilization StructuresSource reviewed 2026-10-28
- Canal, Roads Names and Areas (List of Keys Residential Canals by location)Source reviewed 2026-10-28
- Florida Keys Area of Critical State Concern Annual Report, FY23-24 (reporting period July 1, 2023 - June 30, 2024)Source reviewed 2026-10-28
- CO-OPS Metadata API: datums for station 8723970 Vaca Key, FLSource reviewed 2026-10-28
- Hurricane Wilma (2005) event summarySource reviewed 2026-10-28
- Appendix G: King Tide and Normal Wind Setup Analysis for Monroe County, FloridaSource reviewed 2026-10-28
- Tropical Cyclone Report: Hurricane Irma (AL112017)Source reviewed 2026-10-28
- CDBG-DR Infrastructure Marina (Rebuild Florida/Long Term Recovery list)Source reviewed 2026-10-28
- LDR Sec. 104.64 Waterfront Walkways And DocksSource reviewed 2026-10-28
- Code Sec. 36-88 Mangrove MaintenanceSource reviewed 2026-10-28
- BuildingSource reviewed 2026-10-28
- Permit and Inspection InformationSource reviewed 2026-10-28
- Building Frequently Asked QuestionsSource reviewed 2026-10-28
- Resolution 2025-73, Exhibit A Permit Fee ScheduleSource reviewed 2026-10-28
- LDR Sec. 106.38 Allowable ActivitiesSource reviewed 2026-10-28
- Requirements to Obtain a Dock, Boat Lift, Mooring Piles or Swim/Observation Platform PermitSource reviewed 2026-10-28
- SED Marathon OfficeSource reviewed 2026-10-28
- Rule 62-330.051, F.A.C. (Exempt Activities)Source reviewed 2026-10-28
- Jacksonville District Regulatory Office LocationsSource reviewed 2026-10-28
- Canal RestorationSource reviewed 2026-10-28
- Tropical Cyclone Report: Hurricane Wilma, 15-25 October 2005Source reviewed 2026-10-28