Overview
Port Mayaca is the gate between the St. Lucie Canal and Lake Okeechobee, on the east side of the lake. The chamber is 400 by 56 feet and the lift is small: normally half a foot to 2 feet. The approach channel is 100 feet wide and 8 feet deep. About 9,500 vessels lock through in a year, roughly 96 percent of them recreational.
The lock was built in 1977, for navigation and to permit the raising of water levels in Lake Okeechobee, and its discharge capacity is 14,800 cubic feet per second. From here it is 23.9 miles back east to St. Lucie Lock, and either 39 miles across the open lake on Route 1 or 50 miles round the rim canal on Route 2 to the Julian Keen lock.
The bridge before the lock
A boat coming from the east passes the railroad lift bridge at Mile 38.0 before it reaches the lock. Coast Pilot 4 gives that span clearances of 7 feet down and 49 feet up, and says 49 feet is the minimum clearance under bridges across the whole Okeechobee Waterway – the figure that decides the crossing for a sailboat. Coast Pilot 4 refers the clearances on this canal to a canal stage rather than to a tidal datum, so it is a published figure at a reference level, not a reading of the day.
The U.S. 98–441 highway bridge follows at Mile 38.8, and the waterway enters Lake Okeechobee at Mile 38.9.
Where the lock is, and the chapter against itself
Coast Pilot 4 prints the lock at Mile 40.0. The same chapter also places it about 300 yards west-southwest of the U.S. 98–441 highway bridge, which it puts at Mile 38.8, with the lake beginning at Mile 38.9. Those two statements cannot both be measured the same way. We show Mile 40.0, the figure the chapter prints as the lock's mile, and we do not decide the rest.
The depth is the second disagreement. USACE publishes "56 feet wide x 400 feet long x 14 feet deep" and labels it the lock chamber; Coast Pilot 4 gives "a depth of 16 feet over the sill". Depths change, and the figure that applies on the day is the one on the gauge at the lock.
Tying up
There are no piers in the community, but Coast Pilot 4 reports that one wall of the lock is still present and can be used to tie up, and that government-owned tie-up dolphins stand immediately above and below the lock. Some supplies are available in the community. The lock answers on 561-924-2858.
Facilities
- Piers in the communitynone; Coast Pilot 4 reports one wall of the lock still present and usable to tie up
- Suppliessome are available in the community (Coast Pilot 4)
- Tie-up dolphinsgovernment-owned, immediately above and below the lock
Good to know
- Two ways across the lake from here. Route 1 runs 39 miles across the open lake; Route 2 follows the south rim for 50 miles. Coast Pilot 4 says Route 2 is marked by daybeacons and is the route most used.
- The lift here is small. Normally half a foot to 2 feet – this lock exists to hold the lake, not to raise boats far.
- Hours and radio, as elsewhere on the waterway. USACE gives 7 a.m. to 5 p.m., 365 days a year, last lockage beginning at 4:30 p.m., and channel 13 for the locks; Coast Pilot 4 says 0600 to 2130 daily. Both are primary.
Rules that apply here
- Life jackets on, engines off. The lock operator requires every person aboard to wear a Coast Guard approved life jacket and engines to be turned off.
- Approach only on instruction. Public address systems are installed at all the locks; craft approach for passage only on instruction from the lock tender, by loudspeaker or by standard light signal.
Questions
How tall is the bridge at Port Mayaca?
Coast Pilot 4 gives the railroad lift span at Mile 38.0 clearances of 7 feet down and 49 feet up, and calls 49 feet the minimum clearance under bridges across the Okeechobee Waterway. Coast Pilot 4 refers the clearances on this canal to a canal stage rather than to a tidal datum, so it is a published figure at a reference level, not a measurement of the day – check the current chart and the Local Notice to Mariners.
What mile is Port Mayaca Lock at?
Coast Pilot 4 prints Mile 40.0, and that is what we show. The same chapter also puts the lock about 300 yards west-southwest of the U.S. 98–441 bridge, which it places at Mile 38.8, with the lake starting at Mile 38.9. The chapter contradicts itself and we do not decide it; the lock answers on 561-924-2858.
How far is it across Lake Okeechobee?
From Port Mayaca to the Julian Keen lock it is 39 miles across the open lake on Route 1, or 50 miles round the south rim on Route 2. The two were built to different project depths, which the waterway page lists; Coast Pilot 4 says Route 2 is marked by daybeacons and is the route most used.
Can I tie up at Port Mayaca?
There are no piers in the community. Coast Pilot 4 reports one wall of the lock still present and usable to tie up, and government-owned tie-up dolphins immediately above and below the lock. Some supplies are available in the community.
Sources & checks
- NOAA Coast Pilot 4, ch. 12 (2026) · 18 Oct 2026
- USACE – Port Mayaca Lock and Dam · 21 Oct 2026