Canal Dredging in South Florida: What to Expect From Survey to Spoil

Canals fill in. Runoff carries sand and silt off the land, tides push it in from the main channel, and storms drop it all at once. The signs: the lift cradle sits in mud at low tide, the depth finder reads less every season, and the boat plows a brown wake leaving the slip.

Maintenance dredging is the fix. Florida law defines it as restoring an existing man-made canal or channel to its original design specifications or configurations, which is what most residential jobs are: putting back the depth the canal was built with. [flsenate.gov]

The order is survey, permit, dredge: the survey says how much is there, the permit how much you may remove.

Two numbers matter. The first is the regulatory ceiling: under Florida's maintenance-dredging exemption, unless older permits from the Trustees of the Internal Improvement Trust Fund or the Army Corps show a deeper original design, dredging is limited to no more than 5 feet below mean low water. [flsenate.gov]

The second is practical: enough water under the hull, the lift cradle or the lower unit at the lowest normal tide. A boat-lift manufacturer's guide notes that canals in South Florida can fluctuate up to 2.5 feet in most areas and advises measuring depth at the lowest tide point. [hurricaneboatlifts.com]

Measure at low water, not at noon, and add a margin for future silt.

A bathymetric survey sets the starting point. It maps the bottom in the datum the permit uses and is used to calculate the volume of material to remove, which is how a contractor sizes the job in cubic yards. [oceanconsultingfl.com]

Hydraulic dredging removes sediment by mixing it with water to form a slurry, which is then pumped through pipelines to a dewatering area. It performs best with loose, fine-grained sediments and large, open areas. [pilebuck.com]

Mechanical dredging uses heavy equipment to dig up the bottom with a bucket, from a barge or the seawall. It is most often used to remove rock and gravel and allows more mobility in tight spaces; the choice depends on sediment type, contamination levels, disposal requirements and proximity to shore facilities. [imsdredge.com]

For a private slip with a dock, a lift and a seawall in the way, mechanical dredging is usually the practical choice: it handles sand, shell and debris and needs less pipeline and staging room. Langley's equipment runs from 100,000-pound excavators and land cranes to mini excavators and skid steers, so the machine matches the access.

The spoil does not go back in the water. The exemption requires a self-contained upland spoil site that prevents the escape of the spoil material into the waters of the state. [flsenate.gov]

On a hydraulic job the slurry is pumped to sealed containers in an area accessible by truck, the water extracted is filtered and returned, and the solids are hauled off. Dewatering bags or geotextile tubes do the same work where there is room to stage them. [gatordredging.com]

The work is the short part. For a single boat slip, one Florida contractor's FAQ says the actual dredging takes about a week. [gatordredging.com]

A shared canal takes longer. Lauderdale-By-The-Sea's Phase 1 canal dredge began the week of December 12, 2022 and took about two months, after permits the town had been pursuing since 2020. [lauderdalebythesea-fl.gov]

Permitting is the long part: a verified maintenance exemption is fastest, a full state permit with federal review runs months, and anything needing a Miami-Dade public hearing or seagrass mitigation runs longer. Details are in the permits guide.

How often a canal needs dredging is not a fixed interval, and we will not quote one. It depends on runoff, whether the canal is a dead end or a through channel, boat traffic and the last storm season. Have the depth checked every few years and after a major storm.

It depends on the canal and the city. Fort Lauderdale runs a residential canal dredging program with its own crews and barge, using the clamshell method and draining the sediment in a container aboard the barge before trucking it to a landfill. [fortlauderdale.gov]

Some neighborhoods sit inside a dependent special district that funds its own work; the Lauderdale Isles Water Management District lists canal dredging among its services. [fortlauderdale.gov]

Elsewhere, towns and associations pass assessments. Longboat Key approved a 2026 canal dredging assessment with an 80/20 split between canal-facing homeowners and all other property owners. [yourobserver.com]

City programs, where they exist, dredge the shared channel, not your slip; the water under your lift is generally yours to maintain. If the shoaling is in your slip, plan on a private job, and if neighbors share the problem, one mobilization for the whole canal beats four.

Dredging next to a seawall has to respect the wall. Digging below its footing or too close to its toe removes the soil that holds it. Before dredging, we look at the wall's condition, footing depth and any voids behind it, then set the dredge depth and setback to what the wall can take; a wall that needs repair gets it first. Langley inspects seawalls with underwater photos and video and repairs them, so the two jobs are planned together.

Cost is priced on the job, not by the foot, and the drivers are the same everywhere.

Volume. Depth times area, from the survey, gives cubic yards. Contractors describe the structure as a mobilization fee plus a per-cubic-yard charge for dredging and removal. [thehulltruth.com]

Material, access and haul. One Palm Beach dredging contractor says residential projects scale with volume removed, spoil disposal distance and site access. [palmbeachdredging.com]

Loose silt pumps; compacted sand or shell has to be dug. An open seawall is easy; a lift, dock and pool cage in the way are not. Every truckload goes to a permitted upland site, so haul distance counts. And a verified exemption costs less time than a full permit with mitigation. Langley does not publish prices; a site visit and a survey come first.