In 1996 the Stormwater Management Division divided Cobb County into quadrants and commenced a county-wide storm drainage structure inventory; floodplain mapping update;  and a basin-by-basin hydrologic and hydraulic modeling effort.  A major objective of this program was to update the Federal Emergency Management Agency’s (FEMA’s) flood insurance study stream models (hydraulics and hydrology), many of which were over 25 years old, to reflect current levels of urbanization in the County, and to project floodplains reflective of future basin build  out conditions in 2030.

The initial effort to inventory and study these four quadrants (Priority Areas) of Cobb County has been completed. Some beneficial spin-off programs resulting from this effort included the:

  • County-wide Survey Benchmark Database;
  • County-wide updated floodplain mapping;
  • Noonday Creek Floodplain Acquisition Program;
  • Nickajack Creek Floodplain Acquisition Program;  
  • Flood Storage Volume Purchase Program for existing privately-owned lakes and dams;
  • Enhanced Stream Buffer Program;
  • Regional Stormwater Management Facility at Chastain Meadows Parkway;
  • Regional Stormwater Management Facility at Mark Avenue;
  • Stormwater’s Asset Management Program

This program was one recommendation in the first Priority Area basin study completed in 1998.  New in-stream impoundments are difficult to permit through the Section 404 Wetlands Permitting Program. To address this situation, the concept to acquire, create, and/or purchase significant new storage volume areas in existing impoundments emerged to at least partially offset increased stormwater volumes resulting from urbanization. Additional stormwater flood storage volumes can most easily be created on the surface of existing impoundments, by simply lowering the normal pool level of the lake. Dropping the normal pool level in these existing impoundments creates more “freeboard” (which also promotes dam safety). Purchasing the created flood storage volumes pays for the public benefit while simultaneously providing the dam owners revenue to perform necessary maintenance or upgrades on their dam(s) and/or lake(s).

The Cobb County Board of Commissioners (BOC) has authorized the purchase of floodplain along the following major creeks.

  • Noonday Creek
  • Nickajack Creek
  • Powder Springs Creek
  • Sweetwater Creek
  • Butler Creek
  • Rubes Creek

It is believed that these floodplain areas provide some of the best natural, self-sustaining flood mitigation and water quality improvements within the County. As people continue to move into Cobb County, the pressure to develop even what was previously considered to be “unsuitable land” increases. These floodplain areas provide an irreplaceable public benefit in terms of flood control, wildlife sanctuary, passive recreation, and natural assimilation of non-point source pollutants. The preservation of these major floodplain areas by fee- simple ownership, and the creation of riparian canopied “Town Forests” along these major streams, is a critical long-range goal of the Stormwater Management Program.

Currently, Cobb County is following the directives of Georgia Environmental Protection Division (GAEPD) and of Atlanta Regional Commission (ARC) to comply with rules and regulations regarding Total Maximum Daily Load (TMDL) implementation. To date, all of Cobb County 303d-listed streams are on the list due to fecal coliform levels that are higher than the State standard (200 colonies per 100 milliliters). TMDL implementation plans to both the Chattahoochee and Etowah basins in Cobb County have been submitted to the District.  These plans are contained in this website and detail the preventative programs Cobb County has implemented to address non-point source pollutants identified on GAEPD 303(d) list of impaired waters.