Coastal Services Center

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Northeast Florida  > Navigation Safety

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Shallow Water Bathymetry for the St. Johns River

Dangers to Navigation and Changes in Depth Identified

Submerged wreck located with side scan sonar after hurricane Frances.

Changing water depths, shoals, and obstructions to navigation are of the utmost importance to boaters. NOAA's Office of Coast Survey identified many changes to soundings, or depth, and a record 45 previously unknown obstructions to navigation on the St. Johns River between Mayport and Palatka with this bathymetric survey. Bathymetry is also helpful for modelers who are trying to predict flood ranges, erosion impacts, and the likely movement of hazardous spills and harmful algal blooms.

Submerged wreck is marked on the navigation chart, as shown here, to warn mariners of the danger.

The last complete bathymetric survey of the St. Johns took place in 1940. In 1977, the area from Green Cove Springs north to Jacksonville and east to Mayport was updated. However, only supposed navigational impediments were investigated in the area from Green Cove south toward Palatka at that same time. Maybe that is why 45 obstructions found between Mayport and Palatka were discovered. These obstructions, or submerged hazards that can ground mariners and damage vessels, were classed as "Dangers to Navigation" because they were not previously charted. (Read, too, about the survey's unexpected historical find.)

Hurricane Impacts

New obstructions and shoals are often found after the passing of a hurricane. When hurricanes are approaching, the U.S. Coast Guard’s captain of the port will close the port to ship entry. After the storm has passed, the entrance channels must be surveyed for obstructions before they are reopened. The Office of Coast Survey’s Navigation Response Team 2 traveled to nine ports in three weeks after Hurricanes Frances, Ivan, and Jeanne. The data helped ensure navigational safety through updated critical nautical charts and new information for emergency response organizations to use in the wake of a marine casualty or coastal storm.

Product Availability

Preliminary data are available upon request from David Elliott at (912) 786-4503. After processing the data in a geographic information system, verified data will be made available to all interested federal, state, and local organizations. These data may be requested by calling the Hydrographic Surveys Division, David Scharff, (301) 713-2698. Nautical charts may be ordered from the Distribution Division by calling (800) 638-8972. Other products and services are offered at www.nauticalcharts.gov.

For Additional Information

Edward Myers
NOAA National Ocean Service
Coast Survey Development Laboratory
Telephone: (301) 713-2809, ext. 107
E-mail: Edward.Myers@noaa.gov