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Part of Gwinnett County's storm water strategy is to protect people's lives and property during extreme flooding events such as the 100-year flood. One of the results of this strategy is that Gwinnett County is a participating community in the Federal Emergency Management Agency (FEMA) National Flood Insurance Program (NFIP). As a part of that program, maps are made that identify the 100-year flood plain called Flood Insurance Rate Maps (FIRMs). There are special development regulations in areas that are part of the flood plain. Most of the flood plain maps in Gwinnett County are based on old studies and there are many areas where the flood plain has not been identified. Therefore, we have a six-year program to study and identify the floodplain in the county by 2006. The study will use modeling based on land use and topography to identify the flood plain. Because or our efforts to update our maps, Gwinnett is the second county in Georgia to become a Cooperating Technical Partner (CTP) with FEMA. The partnership will allow the county to have digital FIRMs (DFIRMs) that will be integrated with our GIS system. Our maps will be combined with city flood maps to produce seamless maps across the county. We are currently working with FEMA to produce the new DFIRMs and are on schedule to have preliminary Countywide DFIRMs by July 2004. As a CTP, we have more input on what is shown on our maps and the time FEMA needs to review our flood studies will be reduced.

The flood studies will also be used to identify roadway structures that do not have the capacity to carry peak flows from the 100-year flood event. As stated previously in the section on Post Construction Storm Water Management Strategy, Gwinnett County's policy on flood protection is to size the bridges and culverts for our road system based on this future 100-year flow. A preliminary plan and funding requirements will be determined so that these costs can be included in the County's Capital Improvement Programs (CIPs).


Gwinnett County Flood Study Program Watershed Map
We currently have seven basins under various stages of study (See Map Below). The basins are Apalachee River, Alcovy River, Beaver Ruin Creek, Big Haynes Creek, Crooked Creek, Jackson Creek , Mulberry River, Sweetwater Creek, and Upper Yellow River. The Apalachee River, Alcovy River, Beaver Ruin Creek, Big Haynes Creek, Crooked Creek, Jackson Creek, and Mulberry River flood studies have been submitted to FEMA and are currently under review.

Flood Study Program Map