Back to top

Stormwater Management

Stream flowing through field with vegetation on both side of the banks

FAQ Topics

What is Stormwater?

Stormwater water is that portion of rainfall that does not soak into the ground. It is the rainfall that “runs off” the surface into natural and man-made conveyance systems. Stormwater naturally flows downhill according to the law of gravity. 

Why is stormwater so important?

All life on Earth is fundamentally connected to and is fundamentally dependent upon water. We rely on water as a drinking source; irrigation of crops; solvent for cleaning purposes; hydro-electric power; and recreation. Stormwater is an important part of the earth hydrologic cycle that is essential to all life on earth as we know it. 

What is Non-Point Source Pollution?

Point Source pollution is delivered to the system at a specific point, such as at a pipe outfall from an industrial facility or waste water treatment plant. Non-point source pollutants are widely swept up by stormwater runoff across the surface. Oil on parking lots, septic tank overflows, sedimentation from construction sites, fertilizers from lawns and/or agricultural areas, and excrement of wild and domesticated animals are all examples of non-point source pollutants. 

Where can I find Cobb County’s Ordinances pertaining to “Stormwater Management”?

Go online at:
Go to Section 50, 58 and 110-619(f) in the current Cobb County Code. 

Where can I find Cobb County’s Development Standards related to “Stormwater Management”?

Go to Community Development Agency located at 1150 Powder Springs St, Suite 400, Marietta, GA 30064 or call (770) 528-2130 or check online.

What does “NPDES” stand for and what is its relevance to Stormwater Management?

NPDES stands for National Pollution Discharge Elimination System. Cobb County maintains a five-year permit to discharge stormwater into the municipal stormwater management system. To renew our permit each year, we must demonstrate that we are monitoring our streams; that we are complying with all applicable state and federal laws; and that we are employing sufficient Best Management Practices (BMPs) to protect and enhance water quality. 

What laws govern Stormwater Management? ( ref. to Volume 29 of GEORGIA LAW, 1998 Revision, by James S. Rankin, Jr. of the Georgia Bar, “Water”, pages 30 through 65).

Georgia has adopted the Eastern Rule of Common Law doctrine which establishes the general water quality rather than its quantity has been the governing consideration in fixing the rights of individual users of water.

  • “A Georgia statute provides that the right to throw water on the land of another is an incorporeal right which may be granted by prescription, (O.C.G.A. § 44-5-175 (GCA § 85-409), and it has been stated that, in all cases, special rights to the use of watercourse or to flow water onto the land of another may be acquired by prescription (Watkins v. Pepperton Cotton Mills, 162 Ga. 371 S.E. 69 (1926))”.- page 32.
  • A prescriptive right to throw water upon the land of another may arise through 20 years uninterrupted use (pg 64).
  • “Georgia does not impose strict liability on any party for damage caused by surface water runoff. Liability must be based on intentional or negligent conduct which proximately causes water damage.” (Uniroyal v. Hood) 
  • “The diversion of a stream so as to injure adjacent land constitutes a tort for which damages may be recovered (pg 49). 
  • “County cannot be liable for nuisance which does not rise to the level of taking of property…” (pg 53). 
  • A downstream property owner is obligated to receive the water that flows down upon his property by gravity from the upgradient property(s). However, “…it is now well established in Georgia that one land proprietor has no right to concentrate and collect surface water so that it is discharged upon the lower tract in greater quantities at a particular locality, or in a manner different from that in which the water would be received by the lower estate if it simply ran down upon it from the upper by the law of gravitation.” (Cox v Martin, 207 Ga 442, 62 S.E. 2d 164(1950); Weimer v. Cauble, 214 Ga 634, 106 S.E. 2d 781 (1959); McMillen Development Corp. v. Bull, 228 Ga 826, 188 S.E. 2d 491 (1972). 
  • “Conversely, the lower proprietor may not, by raising his lot, or by any other means, throw the surface water back upon the upper lands of another” ( Farkas v. Towns, 103 Ga. 150, 29 S.E. 700 (1897); Mallard v. Pye, 216 Ga 645, 112 S.E. 2d 620 (1960); Edgar v. Walker, 106 Ga. 454, 32 S.E. 582 (1898)…pages 59-60. 
  • “…It has been said in general terms that a landowner could take such reasonable precautions for his own protections as might be necessary to control such water on his own premises, and to this end might build a wall on his own land, provided it does not back up the water above or stop its natural flow below.” (Hendrix v. McEachern, 164 Ga 457, 139 S.E. 9 (1927). “ He cannot build gutters, sewers, ditches, or drains which concentrate water so as to throw it against his neighbor’s buildings in larger volume than would naturally flow. ( Goldsmith v. Elsas, 53 Ga. 187 (1874). “It may, therefore, be necessary to negotiate with the adjoining owners for easements.” (O.C.G.A. § 44-5-175 (GCA §85-409) – pg 61. 
What stormwater services are currently provided?
  • Plan Review Analysis 
  • Rezoning and Variance Application Analysis 
  • NPDES Permit Compliance Program (Stormwater Environmental Compliance) 
  • Detention/ Retention Pond Information and Education 
  • FEMA Community Rating Service (CRS) Program 
  • Floodplain Mapping and Information 
  • Floodplain Acquisition Program 
  • Flood Storage Volume Purchase Program 
  • Basin Master Planning Program 
  • Limited West Nile Vector Control Program 
  • Limited Storm Drainage Structure Maintenance Program. CCSWM maintains and replaces all non-private, dedicated structural infrastructure, recorded on the Final Plat and formally accepted by Cobb County for perpetual maintenance. 
What stormwater related services are NOT currently provided?

Privately owned stormwater management facilities (pipes, ponds, dams, open channels) are maintained by the property owner. This primarily includes stormwater infrastructure on commercial property or contained within subdivision ‘common areas’ (‘common areas’ are private properties, as are commercial properties). All lakes and ponds (including stormwater detention ponds) not deeded to Cobb County are considered privately owned properties. At the present time, maintaining open channels is also the responsibility of the affected property owner. 

How do I report a stormwater violation?

Call the Stormwater Management Department, Water Quality, Stormwater Environmental Compliance Section at 770-419-6435

What is a Drainage Easement?

A drainage easement is recorded on the Final Plat and conveys the right to use private property for stormwater conveyance. A drainage easement can apply to an open ditch, a 100-year floodplain, a flood pool in a stormwater detention pond, or a closed pipe system. Rights may be granted by prescription (a prescriptive drainage easement may exist) if stormwater has flowed along a defined path (pipe or ditch) for over 20 years. 

Who is responsible for maintaining open ditches?

Currently, Cobb County places the responsibility for maintaining open drainage ditches lies with the individual property owner [ref. Cobb County Code §110-61(f)]. 

I own a dam, lake or pond. Who is responsible for maintaining it?

According to Civil Law in the State of Georgia, the owner of a dam is responsible for maintaining and operating their dam in a safe manner, regardless of how or when areas downstream from the dam develop. Maintenance of a lake or pond is the responsibility of the owner(s) in the absence of a maintenance agreement stating otherwise. 

Who is responsible for maintaining the stormwater detention pond inside a “Common Area”?

Privately owned stormwater management facilities are maintained by the property owner. This includes stormwater infrastructure on commercial property or contained within subdivision common areas. 

How do I find information on maintaining a detention/ retention pond?

Contact the Stormwater Environmental Compliance section at 770-419-6432 for more information. Go to the Georgia Stormwater Management Manual (GSMM) website for information on detention and retention ponds. 

What is the difference between Private versus Public Problems?

According to the current County Code, public responsibility for stormwater maintenance is limited to the structural infrastructure (pipes and pond) formally dedicated to and accepted by Cobb County for perpetual maintenance. The responsibility for maintaining all private property beyond formally dedicated and accepted structural infrastructure (pipes and ponds) rests with the individual property owner. 

What is FEMA?

FEMA stands for the "Federal Emergency Management Agency". Among other things, this federal agency is responsible for the administration and implementation of the National Flood Insurance Study Program. 

Where can I get floodplain maps of my property?

Flood maps of your area are available at the FEMA Flood Map Service Center.

Where can I get information on how to reduce flooding, flood insurance, mapping, repetitive loss, etc.?

FEMA has a number of publications available explaining techniques to reduce flooding, which is available to homeowners at the Stormwater Management Division office and additional information is available at and The United Geological Survey (USGS) WaterAlert service sends e-mail or text messages when certain parameters measured by a USGS data-collection station exceed user-definable thresholds. Instructions for this service are located at

Who can purchase flood insurance?

Any property owner can purchase flood insurance. A property need not be contained within a designated regulated floodplain to qualify for the purchase of flood insurance. 

Who do I talk to concerning flood damage, repetitive loss, floodplain mapping, etc. and to review FEMA publications?

To set up an appointment at our office to discuss the specifics of your situation or to review FEMA publications, please call our office at 770-419-6435

Who/what determines whether I must purchase flood insurance?

According to the Flood Insurance Reform Act passed by Congress in 1994, lending institutions (i.e. banks and mortgage companies) are responsible for making the determination as to whether or not a property is contained within a regulatory floodplain and is required to have flood insurance. If a loan is federally insured, and the property is in a federally regulated Zone “A” or Zone “AE” floodplain, banks are supposed to require borrowers to purchase flood insurance as a condition of the loan. 

What is a CLOMR?

A CLOMR stands for a Conditional Letter of Map Revision. Generally speaking any modification or encroachment into a regulatory floodway necessitates a CLOMR. In Cobb County, any encroachment into the floodplain which either affects the regulatory floodway or increases the base flood elevation by more than 0.01 feet necessitates a CLOMR submittal to FEMA. 

What constitutes a “Substantial Improvement’?

A substantial improvement is defined as any modification to the house which affects more than 50% of its fair market value.