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State, Federal Agencies Work To Make New Cooper River Bridge Turtle-Friendly 

August 2005

Loggerheads use the island beaches around Charleston and Mt. Pleasant to come ashore and lay eggs. The hatchlings use the brighter horizon over the ocean to find their way to sea. Sally Murphy, S.C. Department of Natural Resources (DNR) sea turtle
Loggerhead Sea Turtle

biologist,  said the concern was that lighting for the bridge would disorient loggerhead hatchlings away from the ocean. "We knew the existing 'glow' of the cities was already causing disorientation problems as far away as Dewees Island, which is several miles to the north of Charleston," Murphy said, "and did not want to increase the light problem even more."

To learn more about sea turtles on the South Carolina coast, check the new DNR Web site. There can be found the latest information on conservation efforts, easy access to sighting forms as well as video of turtles in their natural habitat. Also, find out more about the Ravenel Bridge at

Murphy said the lead role to control the lights on the bridge came from U.S. Fish and Wildlife Service biologist Paula Sisson. She knew a similar cable-stayed bridge under construction in Brunswick, Ga., the Sidney Lanier Bridge, was considered for an aesthetic light system. Because that bridge is only a few miles from a known nesting site, the question of lighting impacts on nesting sea turtles was being raised there, but has yet to be resolved.

Ravenel Bridge engineers utilized local ordinances on beachfront lighting and turtles as their guide to resolving the turtle issue.

The Endangered Species Act requires federal agencies to consult with the U.S. Fish and Wildlife Service to ensure they are not undertaking, funding, permitting, or authorizing actions likely to jeopardize the continued existence of listed species or destroy or adversely modify designated critical habitat. The Federal Highway Administration was the lead federal agency with funding support, and the Army Corps of Engineers was the lead for permitting.

Timers were added to the bridge system to eliminate impacts to sea turtles. During the nesting and hatching season (May through October), lights will turn off at 10 p.m. The remainder of the year they turn off at midnight, based on public input for energy conservation. During special occasions, such as the Spoleto Festival, the city might request the lights to remain on a little longer.

The wattage of the system was reduced during the design, and the light circuits can be operated independently to "dim" or reduce the total wattage being used at a given time.

In the interchanges at each end of the bridge, tall "high-mast" light poles are preferred by the S.C. Department of Transportation because they can be maintained without getting into traffic lanes. On the Ravenel Bridge, the Department of Transportation opted for standard-height streetlights that reduced both the amount of light spilling into adjacent neighborhoods and the distance from which these lights could be seen. In addition, the bridge design incorporated reflective road signs as opposed to electrical ones to help reduce the overall amount of light. Murphy said the towers on the bridge could have had a significant adverse impact on loggerhead hatchlings, "Because it's so high, you can really see it a long way off."

- Written by Brett Witt -

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