Gulf Intracoastal Waterway - Alabama Route Segment

Perdido Key, AL to Dauphin Island, AL

The Alabama portion of the Gulf Intracoastal Waterway (GICW) has its beginning near the eastern point of Ono Island, AL at (MM "170.0") at 30°18.6’N / 87°27.3’W.

From this point, the Alabama section of the GICW runs generally in a westerly direction for 58.9 miles ending at 30°15.0’N / 88°23.5’W (MM "111.1") in Mississippi Sound about 2.8 miles NNE of Petit Bois Island’s eastern tip.



Alabama’s GICW is marked with your standard Aids to Navigation. In addition they display yellow triangles or yellow squares. When westbound along this section of the Gulf Intracoastal Waterway, marks displaying yellow triangles should be kept on your starbord hand and those marked with yellow squares should be kept to port. While typically the yellow triangles will be found on red markers and yellow squares are found on green markers, caution should be exercised around Mobile Bay where the GICW intersects or coincides with channels marked by the Lateral Buoyage System.


NOAA chart coverage of this portion of the GICW beginning at mile marker “170.0 EHL” to mile marker “111.1 EHL” is provided by charts #11378 and #11374. These charts can be viewed by clicking on the links below:

Chart #11378 - Santa Rosa Sound to Dauphin Island
Chart #11374 - Dauphin Island to Dog Keys Pass

Distances and Mileages

All distances along the Alabama Gulf Intracoastal Waterway are given in statute miles unless otherwise noted. Statute miles are used in order to conform to the distances shown on the small craft charts typically used along this route.

This portion of the GICW between Ono Island and just north of Petit Bois Pass (Alabama / Mississippi State Line) is measured based on decreasing mileage (East of Harvey Lock - EHL) from (MM “170.0 EHL”) to (MM "111.1 EHL".)


The Federal Project Depth for this portion of the Gulf Intracoastal Waterway provides for a channel depth of 12 feet. While every effort is made to maintain this project depth, the actual controlling depths in the channels may vary due to shoaling reducing the available water depth until maintenance dredging can be accomplished.


Bridges, Locks, & Overhead Power Lines


Alabama Gulf Intracoastal Waterway Bridges

Mile Marker Bridge Charted Vert. Clear. Schedule Restrictions VHF
158.7 EHL Foley Beach Expressway Bridge 73’ Fixed Bridge    
154.9 EHL Gulf Shores Bridge 73’ Fixed Bridge    
127.8 EHL Dauphin Island Bridge 83’ Fixed Bridge 93’ at Center  

The table above lists the bridges, their schedules, and restrictions along Alabama's Gulf Intracoastal Waterway from Ono Island, FL west to Dauphin Island, AL.

This list is believed to be accurate as of July 2018. If any errors or omissions are noted, please e-mail us at with any corrections or recommendations.

This bridge operating schedule can be downloaded for your personal and private use as a ZIP file. The file contains the schedule in Adobe (.pdf) file format.

Alabama Gulf Intracoastal Waterway Bridge Schedule - Download



Overhead Cable and Power Lines

The minimum authorized clearance of overhead cables crossing this section of the GICW is 93 feet and is found at (3) locations along the Alabama GICW: (MM “158.2 EHL”), (MM “154.7 EHL”), and (MM “127.7 EHL”).

Caution - Many of the overhead cables over the waterway carry high voltage, and an extra margin of safety should be allowed when the weather is threatening.


Tidal ranges are fairly small along Alabama’s coast. Under normal conditions the mean range of tide averages slightly more than 0.5’ at Perdido Pass and increases to a little more than 1.2’ at the western end of Dauphin Island.

The type of tide experienced in this area is typically a "Diurnal Tide" - exhibiting (1) high tide and (1) low tide each day.

Inlets & Passes

There are (4) Entrances, Inlets, or Passes between the Gulf of Mexico and this section of Alabama’s Gulf Intracoastal Waterway; (1) of these is only suitable for the smallest of vessels with shallow draft and (1) requires local knowledge. The remaining (2) can be considered navigable for most vessels.

Perdido Pass

Perdido Pass, located between Florida Point and Alabama Point near Orange Beach is easily spotted from offshore by the Perdido Beach Bridge spanning the pass. The bridge has (2) navigational openings. The Clearance for Perdido Pass Channel, leading to the GICW is 54 feet. The Cotton Bayou Channel, leading to Johnson Cove has a clearance of 41’. The dredged entrance channel is protected by a jetties and is well marked.

Chart #11382 will prove useful for those arriving or departing Perdido Pass.

Mobile Bay Entrance

Mobile Bay entrance is 3 miles wide and is located between Mobile Point and Ft. Morgan to the east and Pelican Point on Dauphin Island to the west near (MM "134.0 EHL") of the GICW. The main shipping channel is typically used by most vessels without local knowledge. The entrance and Mobile Bay Ship Channel is relatively straight, deep, and well marked with buoys, daybeacons, and ranges.

The most prominent features are Mobile Point Light, 125’ high showing a Fl 10s light and the abandoned Sand Island Light tower (131’ black conical tower) just to the west of the entrance channel. The entrance channel is deep and well-marked by buoys and range lights.

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