WallDockDeck
Monroe County · Seawalls

What are the seawall requirements in Monroe County?

No county height ruleconfirmed, not assumed

Monroe is the only county of the four where we can say with certainty that no elevation standard exists, because we read every mention of seawall and bulkhead in the county's code to establish it. That does not make the Keys permissive. Monroe regulates something the other three counties largely do not - whether you may build a vertical wall at all.

Source: Monroe County Land Development Code Sec. 118-12(k), Shoreline Setbacks; Monroe County Comprehensive Plan Policies 210.1.6 and 212.5.1-212.5.4; Monroe County Code of Ordinances Sec. 6-100(b); Key Colony Beach Code Sec. 5-51; Key West Code Sec. 110-182; Marathon LDR Sec. 106.36(H); Islamorada Village Code Sec. 30-1545 · Verified 2026-10

The detail

No minimum, no maximumMonroe County Land Development Code Sec. 118-12(k) sets no elevation and no datum for a seawall or bulkhead. Every seawall and bulkhead reference in the Code of Ordinances, the Land Development Code and the Comprehensive Plan was checked.
The real restriction is locationA vertical seawall or bulkhead is permitted only to stabilise a severely eroding shoreline, and only on manmade canals, channels or basins. Sec. 118-12(k)(3).
It is a last resortPermitted only if native vegetation, or riprap and filter cloth, is not a feasible means to control erosion. Sec. 118-12(k)(3).
Open water is closedNo new seawalls, bulkheads or other hardened vertical structures are permitted on open water. Comprehensive Plan Policy 210.1.6 goes further - seawalls are prohibited on any beach or open-water shoreline.
Repair is protectedA lawfully existing deteriorated seawall may be repaired or replaced, and is exempt from the nonsubstantial-improvements limit, except on known or potential sea turtle nesting beaches. The work must keep the existing footprint to the maximum extent practicable. Sec. 118-12(k)(4).
Turtles outrank the wallNo seawall, bulkhead or riprap on or waterward of a beach berm complex that is known or potential marine turtle nesting area, as determined by the County Biologist. Sec. 118-12(k)(7).
Riprap and mangrovesRiprap at the toe wherever feasible, and barriers placed landward of existing mangroves whenever feasible. Sec. 118-12(k)(5) and (6).
The one height-adjacent ruleExisting grade landward of the bulkhead must be at least six inches lower than the top of the bulkhead. Sec. 118-12(k)(2). That fixes grade against the cap. It does not tell you how high the cap must be.
A wall with no houseA seawall without a principal use may have a cap no more than two feet wide. Sec. 118-12(k)(1).
State and federal come firstAll such projects require state and/or federal permits before construction and before the county issues a Notice to Proceed. Sec. 118-12(k)(9). A separate county permit is required for a seawall. Code of Ordinances Sec. 6-100(b).
One city does set a heightKey Colony Beach requires 5.5 ft above mean sea level (Code Sec. 5-51). Of the other Keys codes we have read, none sets one: Key West (Sec. 110-182), Marathon (LDR Sec. 106.36(H)), Islamorada (Village Code Sec. 30-1545) and unincorporated Monroe (LDC Sec. 118-12(k)), which is the rule for Key Largo, Tavernier, Big Pine Key, Cudjoe Key and the other unincorporated Keys. We have not yet read Layton's code.

Your city's height sheet

The elevation your city requires, the datum it is measured in, and the section of code that says so. One page.

Available for the cities whose rule we have verified and sourced.

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Your city, specifically

24 published across 4 cities: Islamorada, Key Colony Beach, Key West, Marathon.

Seawall height requirement

IslamoradaNo minimum set in local codeKey Colony Beach5.5 ft above mean sea levelKey WestNo minimum set in local codeMarathonNo minimum set in local code

Seawall permit process

IslamoradaYes village building permitKey Colony BeachYes, after state and federal approvals city building permitKey WestYes city building permitMarathonYes city permit; state/federal approvals first

Dock permit & size limits

Islamorada10% of waterbody width max; pier docks no longer than 100 ftKey Colony Beach5 ft into the canal default; 30-125 ft in named subdivisionsKey WestNo fixed size limit; 4 ft depth rule dock must link to a channel at least 4 ft deep at mean low waterMarathon100 ft or 10% of waterbody width max dock length from mean low water; ends in 4 ft of water

Boat lift rules

IslamoradaAllowed; covered lifts only over cut-in slips roof max 12 ft above gradeKey Colony BeachAllowed by type; pontoon lifts banned davits over 5,500 lb need commissionKey WestNo lift-specific rule; permit fee covers davits building permitMarathonAllowed; lift max 5 ft above dock covered lifts to 20 ft above MHW

Waterfront deck requirements

Islamorada10 ft from MHW or mangroves for elevated decks, pavers, gazebos and pool decks on canal lotsKey Colony Beach10 ft pool setback from mean high water on canals; 60% of the shoreline setback may be built onMarathon10 ft minimum buffer from MHW or mangrove roots for accessory structures on canal lots

Checking a marine contractor

IslamoradaRegister with the Village CityView business account; annual feesKey WestCity licence + competency DBPR contractors register online

Storm prep & documentation

IslamoradaOwner's responsibility debris on private property, including boats in canalsKey Colony Beach120 percent strap rating for boats left on liftsMarathonRight of entry to clear debris from private canals

Twelve signs a seawall is failing

What to look for, where to look for it, and what it means when you find it. Walk your wall in twenty minutes.

A screening sheet for owners, not an engineering inspection.

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