Grassy Key, Crawl Key and Fat Deer Key seawall repair
Grassy Key, Crawl Key, Fat Deer Key and Long Point Key are all inside the City of Marathon, so the city permits seawall work here. The shoreline is mostly park and mangrove, with only a few residential canals.
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Grassy Key, Crawl Key & Coco Plum (east Marathon) at a glance
- Who permits it
- City of Marathon Building Department
- Call first
- City of Marathon Building, (305) 289-5052
- The water
- Canals 165 to 168, plus Curry Hammock park shoreline
- Storm record
- Georges, 1998: 4 to 5 ft of surge at Grassy Key
- Local rule to know
- Canal mangroves kept within 10 ft or 20% of canal width
Get to know your waterfront
This is Marathon's east end, running up to the Toms Harbor bridge near mile marker 60. Curry Hammock State Park holds all of Little Crawl Key and Deer Key and parts of Fat Deer and Long Point Keys. The county lists only a handful of residential canals, on Grassy Key and Crawl Key.
City of Marathon Charter, Sec. 10 Land Description · Curry Hammock State Park Unit Management Plan · Canal, Roads Names and Areas (List of Keys Residential Canals by location)
Canals, park shoreline and mangroves on Grassy Key
Only four numbered canals appear under Grassy Key and Crawl Key in the county lookup, so most shoreline here is not a canal wall. county canal street list
| Canal | Streets | What the county layer records |
|---|---|---|
165, Grassy Key | Parrish Drive, Morton Street | Listed in the street lookup |
166, Grassy Key | Blue Isle Boulevard, Paradise Place, Edgewater Road | 91 parcels at MM 57, plus a bayside "Grassy Key Added" section at MM 60 with 35 parcels, labeled Poor |
167 and 168, Crawl Key | Banana Boulevard, Ocean Drive | Oceanside at MM 56, 25 parcels, labeled Good; tidal range field about 1.7 feet |
Sources: county canal street list Monroe County canal inventory
The same lookup ties Coco Plum Drive and the lettered Avenues to canals 172 to 201, filed under Marathon. county canal street list Check the county map to confirm which canal fronts your parcel.
Curry Hammock and the passes U.S. 1 closed
Curry Hammock State Park covers about 1,056 acres inside Marathon's city limits. It takes all of Little Crawl Key and Deer Key and parts of Fat Deer and Long Point Keys. DEP park jurisdiction report Curry Hammock management plan
Building U.S. 1 in the 1940s cut through Fat Deer and Long Point Keys and blocked the tidal passes between them and Crawl Key. The park plan calls for culverts under the highway to bring the flow back. Curry Hammock management plan
The park islands rise no more than 5 feet above mean sea level, on Key Largo limestone. Curry Hammock management plan Ask your engineer how that rock will affect piles or tiebacks on your lot.
What an open-water lot can do
- Marathon allows no new vertical seawalls on open water. Marathon code 106.36
- Principal structures stay 50 feet back from unaltered open water, against 20 feet on man-made canals. LDR Table 106.28.1
- Riprap goes landward of existing mangroves, no steeper than 2:1. Marathon code 106.36 See riprap and shoreline stabilization.
Mangroves growing into the wall
Canal owners must keep mangroves within 10 feet of mean high water or 20 percent of the canal width, whichever is less. Trimming needs a DEP permit unless an exemption applies. Code Sec. 36-88
DEP treats trimming mangroves that grow into a seawall as exempt maintenance, and asks owners to send a description and photos first. No Keys government is delegated to run the mangrove program, so the call goes to DEP's Marathon office. DEP mangrove FAQ DEP delegation list
Georges brought 4 to 5 feet of surge to Grassy Key in 1998. Hurricane Center Georges table For storm steps, see the storm damage guide.
What could the work cost?
Grassy Key permits follow Marathon's fee schedule: $17.50 per $1,000 of contract price, a $93.50 minimum, a $4 education fee and state surcharges. Near the park or mangroves, budget time for the natural resources inventory the city requires before any price is final.
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 | Seawall, riprap and dock permits for Grassy, Crawl, Fat Deer and Long Point Keys. | Parcel ID, proof of ownership and a signed contract. (305) 289-5052. |
City of Marathon Planning (City Biologist) | Decides if riprap will suffice and reviews work in mangroves, wetlands and buffers. | A natural resources inventory and your state and federal approvals. |
Florida DEP, Marathon branch | Mangrove trimming questions, seawall exemptions and state permits. | Photos of any mangroves touching the wall. (305) 289-7070. |
Before you plan a Grassy Key wall
Three steps that fit an east Marathon lot.
Use the city portal
Grassy, Crawl, Fat Deer and Long Point Keys sit inside Marathon's charter limits. File and search permits in the city's Viewpoint portal, not the county's system.
City of Marathon Charter, Sec. 10 Land Description · Permit and Inspection Information
Photograph the mangroves
If mangroves grow into your wall, send DEP a description and photos before anyone trims.
Ask about riprap early
On open water or a park edge, a vertical wall may not be an option. Ask the city what riprap design it would accept before you commission drawings.
Plan your Grassy Key shoreline project
Tell us which key you are on, what faces your lot (canal, mangroves or open water) and what you see at the wall. We will help you sort out the next step.
Every answer here links to the public record behind it.
Grassy Key, Crawl Key & Coco Plum (east Marathon) project questions
Is Grassy Key in the City of Marathon or unincorporated Monroe County?
Marathon's charter includes Grassy Key, Crawl Key, Fat Deer Key and Long Point Key. Your seawall permit comes from the City of Marathon Building Department at (305) 289-5052.
City of Marathon Charter, Sec. 10 Land Description · Building
Can I armor a lot next to Curry Hammock State Park?
Marathon allows no new vertical seawalls on open water. Riprap must sit landward of existing mangroves and slope no steeper than 2:1, and principal structures stay 50 feet back from unaltered open water.
LDR Sec. 106.36 Criteria For Approval (Hardened Shorelines) · LDR Sec. 106.28 Water Resource And Wetland Buffers
Who handles mangroves growing into my seawall?
Florida DEP's Marathon office, at (305) 289-7070. DEP treats trimming mangroves that grow into a seawall as exempt maintenance, but asks for a description and photos first.
Keep planning
Nearby waterfront guides
Marathon: Vaca Key & Boot Key Harbor, Key Colony Beach, Duck Key
Show sourcesHide sources
- City of Marathon Charter, Sec. 10 Land DescriptionSource reviewed 2026-10-28
- Curry Hammock State Park Unit Management PlanSource reviewed 2026-10-28
- Canal, Roads Names and Areas (List of Keys Residential Canals by location)Source 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
- 2025-2026 Jurisdiction Report: Florida State Park and Trail Units as of July 1, 2026Source reviewed 2026-10-28
- LDR Sec. 106.36 Criteria For Approval (Hardened Shorelines)Source reviewed 2026-10-28
- LDR Sec. 106.28 Water Resource And Wetland BuffersSource reviewed 2026-10-28
- Code Sec. 36-88 Mangrove MaintenanceSource reviewed 2026-10-28
- Mangrove Frequently Asked QuestionsSource reviewed 2026-10-28
- Mangrove Trimming Delegated Local GovernmentsSource reviewed 2026-10-28
- Preliminary Report: Hurricane Georges (AL071998), 5 January 1999, updated 9 September 2014Source reviewed 2026-10-28
- BuildingSource reviewed 2026-10-28
- Building Frequently Asked QuestionsSource reviewed 2026-10-28
- LDR Sec. 106.38 Allowable ActivitiesSource reviewed 2026-10-28
- SED Marathon OfficeSource reviewed 2026-10-28
- Permit and Inspection InformationSource reviewed 2026-10-28