(Lawrenceville, Ga., Sept. 25, 2009) - Fourteen dams in Gwinnett built in the 1970s to reduce floodplains on what was once agricultural land worked as intended during this week's 100-year frequency rainfall event, holding back billions of gallons of potential floodwater. Steve Leo, the County's stormwater manager, said eight of the Category 1 dams were recently upgraded to meet new state and federal safety standards.

More than 150 homes and businesses plus several schools and community centers have been built in areas that would have been flooded if the dams didn't exist. Leo said four of the upgraded dams north of Lawrenceville control about 17 square miles of drainage area in the upper Yellow River watershed, which was one of the hardest hit during this week's flooding. The water they stored is being released gradually this week to restore their ability to buffer the next storm.

The original earthen spillways at those four dams were converted to wider, stepped concrete structures to protect the integrity of the dams in a larger storm event. Some of the spillways had been covered with soil and grass for beautification. One is located in Collins Hill Park, another is off Christina Drive, and the other two are in the Richland and Channings Lake subdivisions.

Lynn Smarr, Acting Director of Water Resources, said the dams were built in partnership with the National Resources Conservation Service (NRCS). Other partners included the Gwinnett Soil and Water Conservation District and the Upper Ocmulgee Resource Conservation and Development Council. Gwinnett County maintains the structures with funds from its stormwater utility.

There are a total of 14 NRCS dams in Gwinnett. Two already met the new requirements of the Safe Dams Act, eight have been upgraded to the new standards over the past eight years, and the other four are now under construction or being designed for completion by 2012. The County is spending an estimated $20.4 million to upgrade the dams with about a quarter of that total coming from USDA NRCS grants.

"Obviously we're pleased that these dams functioned as designed to prevent the flooding and damage that would have occurred had they not been in place," Smarr said.