Cobb County Government

Programs

Basinwide Study Program ( by “Priority Areas”)
In 1996 the Stormwater Management Division divided Cobb County into quadrants and commenced a storm drainage structure inventory and a basin-by-basin hydrologic and hydraulic modeling effort. The objectives were to update the flood insurance study stream models which were over 25 years old in some cases, to reflect the current levels of urbanization, and to project future 2030 basin build out conditions. At the end of this modeling effort, the consultants were asked to develop a “Recommended Basin” of both structural and non-structural BMPs which would help offset the adverse impacts of urbanization (existing and anticipated future build out) on the stormwater management ecosystem. The initial effort to inventory and study these four quadrants (Priority Areas) of Cobb County has recently been completed. Some of the beneficial spin-off programs that have resulted from this modeling effort include: the Noonday Creek floodplain buyout program; the flood storage purchase program; and the enhanced stream buffer program.

Storm Drainage Infrastructure Maintenance Program
In 1994, the Cobb County Board of Commissioners allocated $1.6 million to the Cobb County Stormwater Management Division to operate and maintain existing dedicated structural stormwater infrastructure. This budget has been increasedeach year to its current level of $6 million annually. At the present time, Cobb County has not authorized or funded the maintenance of open channels, or of storm drainage structures on private property.

Floodplain Mapping Update Program
One main objective of the Priority Area Basin Plans was to update the Federal Emergency Management Agency (FEMA) flood insurance study map to reflect existing levels of watershed urbanization; to estimate future (basin buildout condition) floodplain levels and limits; and to keep development out of these areas. To facilitate the updating of existing floodplain maps, Cobb County has applied to and been accepted into FEMA’s Community Cooperating Technical Partner (CTP) program.

FEMA Community Rating System (CRS) Program
This is a FEMA program in which Cobb County is currently participating. In exchange for reductions in flood hazard potential and elimination of repetitive flood loss property, FEMA promises to lower flood insurance study premiums. Cobb County is currently at a level 8 which offers premium holders a 10% reduction in their flood insurance rates.

Flood Storage Volume Purchase Program (i.e. existing dam retrofit)
This program was one recommendation in the first Priority Area basin study performed in 1998. New in-stream impoundments are getting more difficult to permit through the Section 404 Wetlands Permitting Program. To address this situation, the concept has emerged to acquire, create, and/or purchase significant new storage volume area in existing impoundments to offset some of the adverse effects of urbanization for these higher flow volumes. One of the simplest waysto do this is on the surface of existing impoundments, where additional flood storage volumes can be created by simply dropping the normal pool level of the lake. Dropping the normal pool level in these existing impoundments creates more “freeboard” (a safer condition). Purchasing the created flood storage volumes pays for the public benefit while simultaneously providing the dam owner revenue to perform necessary maintenance or upgrades on his dam.

Flood Hazard Mitigation (GEMA Grants) Floodplain Property Buyouts

Hazard Mitigation Grant Program (HMGP)
In 1999, GEMA awarded Cobb County a 75/25 matching grant to purchase 16 homes in the Noonday Creek floodplain. The grant was later amended to include 16 additional homes located along Leasa Court. All of these homes have now been purchased, and removed from the floodplain. This grant was later amended again in 2004 to include the purchase of 10 homes on Rio Montana.
Flood Mitigation Assistance (FMA) Grants
In 2002, GEMA awarded Cobb County a 75/25 matching grant to purchase 3 homes in the Little Noonday Creek regulatory floodway located on Leasa Court. These homes have been purchased and removed from the floodplain.
Disaster Relief Grants (DR1554) and (DR1560)
On July 11, 2005 Hurricane Dennis struck Cobb County and hit hardest in the southwestern corner of the County in and around Cities of Austell and Powder Springs. Over 70 homes sustained significant damage from the flooding resulting from 12-14 inches of rainfall over a 24 hour period. The flood stage of record (22 feet) was recorded at the USGS streamflow gage on Sweetwater Creek near Austell. Unfortunately a federal disaster was not declared for Hurricane Dennis. To assist Cobb County with local relief efforts, GEMA and FEMA made disaster relief funds available from previous Hurricane Disasters ( Hurricane Francis – September 7, 2004 and Hurricane Ivan – September 16, 2004) . In February 2006, Cobb County was awarded two Flood Hazard Mitigation Grants from GEMA and FEMA to purchase, demolish and remove 26 homes that sustained substantial damage from Hurricane Dennis

Floodplain Acquisition Program
The Cobb County BOC has authorized the purchase of floodplain along the following major creeks.

Noonday Creek
Nickajack Creek
Powder Springs Creek
Sweetwater Creek
Butler Creek

It is believed that these floodplain areas provide some of the County’s best natural, self-sustaining flood mitigation and water quality improvements. As land continues to appreciate in value in 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 judged to be a critical goal of the current Stormwater Management Program.

Total Maximum Daily Load (TMDL) Implementation Plan Program
Currently, Cobb County is following the directives of EPD and of ARC to comply with rules and regulations regarding 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 detain the preventative programs Cobb County has implemnets to addree non-point source polluntants identified on GAEPD 303(d) list of impaired waters.

National Pollution Discharge Elimination System (NPDES) Program
Cobb County maintains a five year “MS4” permit with EPD which grants Cobb County the right to discharge stormwater from municipal stormwater management facilities into waters of the State.

Stream Monitoring Program

Non-point Source pollutants
The outfall monitoring program (performed twice a year) has been changed to a new watershed “in-stream monitoring” approach with more comprehensive chemical and biological screening through Cobb County’s Stream Monitoring program. Tests are conducted under Cobb County’s chemical screening program for pH, temperature, conductivity, heavy metals (copper, cadium, lead), phenols, surfactants, fecal coliforms, BOD, DO, COD, nutrients, and turbidity.
Biological Monitoring
The biological monitoring aspect of the program provides a more comprehensive and accurate understanding of a stream’s health as it reflects acute changes and long term trends in the watershed. A more comprehensive assessment of stream health can be gained through periodic assessments (sample monitoring) of biological diversity in the stream. Cobb County staff members perform in-stream monitoring twice a year and annual biological assessments for all of our major streams.

West Nile Vector Control Program
The Cobb County Water System currently funds four part-time positions for the Health Department for the West Nile Vector Control Program. Cobb County Stormwater Management Division follows directives from the Health Department in the application of larvicide. Currently Stormwater Management treats areas within 900 feet of County-operated Senior Citizens Centers, in County Parks, and within 900 feet of infected birds.




Advanced Home About SWM Historical Perspective Programs Projects FAQ Maps Contacts Photographs William J. Higgins,P.E. Division Manager 680 South Cobb Drive Marietta, GA 30060 Phone: (770) 419-6435 Email	Stormwater Management (SWM) Programs Basinwide Study Program ( by “Priority Areas”) In 1996 the Stormwater Management Division divided Cobb County into quadrants and commenced a storm drainage structure inventory and a basin-by-basin hydrologic and hydraulic modeling effort. The objectives were to update the flood insurance study stream models which were over 25 years old in some cases, to reflect the current levels of urbanization, and to project future 2030 basin build out conditions. At the end of this modeling effort, the consultants were asked to develop a “Recommended Basin” of both structural and non-structural BMPs which would help offset the adverse impacts of urbanization (existing and anticipated future build out) on the stormwater management ecosystem. The initial effort to inventory and study these four quadrants (Priority Areas) of Cobb County has recently been completed. Some of the beneficial spin-off programs that have resulted from this modeling effort include: the Noonday Creek floodplain buyout program; the flood storage purchase program; and the enhanced stream buffer program. Storm Drainage Infrastructure Maintenance Program In 1994, the Cobb County Board of Commissioners allocated $1.6 million to the Cobb County Stormwater Management Division to operate and maintain existing dedicated structural stormwater infrastructure. This budget has been increasedeach year to its current level of $6 million annually. At the present time, Cobb County has not authorized or funded the maintenance of open channels, or of storm drainage structures on private property. Floodplain Mapping Update Program One main objective of the Priority Area Basin Plans was to update the Federal Emergency Management Agency (FEMA) flood insurance study map to reflect existing levels of watershed urbanization; to estimate future (basin buildout condition) floodplain levels and limits; and to keep development out of these areas. To facilitate the updating of existing floodplain maps, Cobb County has applied to and been accepted into FEMA’s Community Cooperating Technical Partner (CTP) program. FEMA Community Rating System (CRS) Program This is a FEMA program in which Cobb County is currently participating. In exchange for reductions in flood hazard potential and elimination of repetitive flood loss property, FEMA promises to lower flood insurance study premiums. Cobb County is currently at a level 8 which offers premium holders a 10% reduction in their flood insurance rates. Flood Storage Volume Purchase Program (i.e. existing dam retrofit) This program was one recommendation in the first Priority Area basin study performed in 1998. New in-stream impoundments are getting more difficult to permit through the Section 404 Wetlands Permitting Program. To address this situation, the concept has emerged to acquire, create, and/or purchase significant new storage volume area in existing impoundments to offset some of the adverse effects of urbanization for these higher flow volumes. One of the simplest waysto do this is on the surface of existing impoundments, where additional flood storage volumes can be created by simply dropping the normal pool level of the lake. Dropping the normal pool level in these existing impoundments creates more “freeboard” (a safer condition). Purchasing the created flood storage volumes pays for the public benefit while simultaneously providing the dam owner revenue to perform necessary maintenance or upgrades on his dam. Flood Hazard Mitigation (GEMA Grants) Floodplain Property Buyouts *Hazard Mitigation Grant Program (HMGP)* In 1999, GEMA awarded Cobb County a 75/25 matching grant to purchase 16 homes in the Noonday Creek floodplain. The grant was later amended to include 16 additional homes located along Leasa Court. All of these homes have now been purchased, and removed from the floodplain. This grant was later amended again in 2004 to include the purchase of 10 homes on Rio Montana. Flood Mitigation Assistance (FMA) Grants In 2002, GEMA awarded Cobb County a 75/25 matching grant to purchase 3 homes in the Little Noonday Creek regulatory floodway located on Leasa Court. These homes have been purchased and removed from the floodplain. *Disaster Relief Grants (DR1554) and (DR1560)* On July 11, 2005 Hurricane Dennis struck Cobb County and hit hardest in the southwestern corner of the County in and around Cities of Austell and Powder Springs. Over 70 homes sustained significant damage from the flooding resulting from 12-14 inches of rainfall over a 24 hour period. The flood stage of record (22 feet) was recorded at the USGS streamflow gage on Sweetwater Creek near Austell. Unfortunately a federal disaster was not declared for Hurricane Dennis. To assist Cobb County with local relief efforts, GEMA and FEMA made disaster relief funds available from previous Hurricane Disasters ( Hurricane Francis – September 7, 2004 and Hurricane Ivan – September 16, 2004) . In February 2006, Cobb County was awarded two Flood Hazard Mitigation Grants from GEMA and FEMA to purchase, demolish and remove 26 homes that sustained substantial damage from Hurricane Dennis Floodplain Acquisition Program The Cobb County BOC has authorized the purchase of floodplain along the following major creeks. Noonday Creek Nickajack Creek Powder Springs Creek Sweetwater Creek Butler Creek It is believed that these floodplain areas provide some of the County’s best natural, self-sustaining flood mitigation and water quality improvements. As land continues to appreciate in value in 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 judged to be a critical goal of the current Stormwater Management Program. Total Maximum Daily Load (TMDL) Implementation Plan Program Currently, Cobb County is following the directives of EPD and of ARC to comply with rules and regulations regarding 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 detain the preventative programs Cobb County has implemnets to addree non-point source polluntants identified on GAEPD 303(d) list of impaired waters. National Pollution Discharge Elimination System (NPDES) Program Cobb County maintains a five year “MS4” permit with EPD which grants Cobb County the right to discharge stormwater from municipal stormwater management facilities into waters of the State. Stream Monitoring Program Non-point Source pollutants The outfall monitoring program (performed twice a year) has been changed to a new watershed “in-stream monitoring” approach with more comprehensive chemical and biological screening through Cobb County’s Stream Monitoring program. Tests are conducted under Cobb County’s chemical screening program for pH, temperature, conductivity, heavy metals (copper, cadium, lead), phenols, surfactants, fecal coliforms, BOD, DO, COD, nutrients, and turbidity. Biological Monitoring The biological monitoring aspect of the program provides a more comprehensive and accurate understanding of a stream’s health as it reflects acute changes and long term trends in the watershed. A more comprehensive assessment of stream health can be gained through periodic assessments (sample monitoring) of biological diversity in the stream. Cobb County staff members perform in-stream monitoring twice a year and annual biological assessments for all of our major streams. West Nile Vector Control Program The Cobb County Water System currently funds four part-time positions for the Health Department for the West Nile Vector Control Program. Cobb County Stormwater Management Division follows directives from the Health Department in the application of larvicide. Currently Stormwater Management treats areas within 900 feet of County-operated Senior Citizens Centers, in County Parks, and within 900 feet of infected birds.
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