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Governments Plan for Development of Land Vulnerable to Rising Sea Level: Chatham County, Georgia

Additional background prepared by the staff of Coastal Georgia Regional Development Center and Jim Titus

Chatham County is home to the historic City of Savannah as well as other heavily populated communities. Along the northern border of Georgia, the beaches of Tybee Island are a major tourist attraction. On Tybee Island, all new residential development is constructed on pilings. Structural fill to elevate buildings is prohibited under the county flood mitigation plan, but fill is allowed for general grading purposes.

Each year, the Environmental Protection Division of DNR receives applications for approximately 60 shoreline alteration permits on Tybee Island. Sloping sea walls are allowed under the Shore Protection Act, but not vertical sea walls, because they do not dissipate wave energy and they increase shoreline erosion. Nourishment is allowed under the act, but is generally conducted only as a private enterprise in Georgia. An application for funding or permit of a seawall triggers a consultation under Section 7 of the Endangered Species Act. The purpose of the consultation is to determine the effects of the construction on affected species. The USFWS prefers carefully implemented renourishment to seawalls and revetments for the viability of the sea turtle and plover populations, provided nourishment occurs outside of nesting season. Even groins and breakwaters can limit the shifting of sand, which is necessary for the successful feeding and nesting of plovers.

The county's Soil Erosion & Sediment Control ordinance requires a buffer of 25 to 50 feet (depending on location and date of development) from state waters. The County Greenspace plan calls for acquisition of land adjoining existing open space. "Permanent protection" under Greenspace rules requires land purchased with program funds to be maintained in a natural state. All of these policies tend to increase land available for wetland migration compared to what it would otherwise be.

Our original meetings with county staff focused on distinguishing lands where shore protection is likely from those areas where it is unlikely or precluded by existing policies. County planners and out general analytical approach aree that the metropolitan area surrounding Savannah will almost certainly be protected. County staff anticipate that the City of Savannah will protect the historic area from sea level rise by constructing dikes along the Savannah River, where it abuts the city. County planners also deem shoreline protection almost certain for Tybee Isle of Hope, and Modena, and Dutch Isle.

The county's major roads will almost certainly be protected to maintain state evacuation routes. In particular, GS-80, which currently floods during high tides, is scheduled to be elevated and widened-possible in 2007. Other evacuation routes include GA-204, GA-21, I-16 and U.S.17 (due to be widened to 4 lanes). County roads have a minimum elevation of 7.5 feet above mean sea level, as required by GADOT. Officials expect these county roads to be maintained and improved, as necessary, to maintain access to public and private property as sea level rise--including the islands. The County will also accept responsibility for maintaining private roads on a case-by-case basis. Ossabow Island is a nature preserve and will not be protected.

Unlike most coastal counties in the state, Chatham County's Metropolitan Planning Commission has a GIS data set with anticipated future land use which contemplates, in effect, the eventual buildout as rural areas are either developed or preserved. Our final maps treat those lands anticipated for future development as likely to be protected. Commercial, industrial, recreational, residential, utility, and other urban lands are almost certain to be protected.

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Governments Plan for Development of Most Land Vulnerable to Rising Sea (PDF, 7 pp., 1.3 MB) was originally published in Environmental Research Letters , Issue 3, Volume 4 (2009).

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