Cobb's New Stormwater Fee and Who Maintains a Detention Pond

Cobb County homeowners have a new line item on the water bill and an old question behind it: when the drainage in a neighborhood fails, who actually fixes it. The county launched a dedicated stormwater utility fee on June 1, 2026, and the answer to the maintenance question depends on where the pipe or pond sits and who owns it. For buyers looking at a lot with a creek, a detention pond, or a drainage easement, this is a due diligence subject rather than a landscaping detail.

This is a process explainer. Confirm the specifics for any address with the Cobb County Water System and, where an association is involved, with the association's own recorded documents and an attorney.

What Is the Cobb County Stormwater Fee?

Cobb County began charging a dedicated stormwater utility fee on June 1, 2026. Residential customers pay a flat $4.75 per month. Non-residential customers are billed based on actual impervious surface area at $4.75 per 3,700 square feet.

Who Pays It

The fee applies to customers in unincorporated Cobb County and the City of Mableton. Customers inside other incorporated cities served by the Cobb County Water System are not charged it. That distinction matters when comparing carrying costs across a city line.

Why the County Changed the Structure

Before June 2026, stormwater costs were bundled into water and sewer charges based on consumption, which meant a household's stormwater contribution tracked how much water it used rather than how much runoff its property generated. The county's stated rationale is that a dedicated fee ensures stormwater funds collected are used exclusively for stormwater services, and that it is more equitable than a consumption-based charge. Cobb's stormwater funding page also references an impervious surface map where property owners can view their own measured area, and notes that credits may be available for certain stormwater management activities.

What It Funds

The county describes the fee as providing needed additional funding to keep up with repairs of failing stormwater infrastructure. That is the important framing for a homeowner: the fee funds the public system. It does not convert private drainage into a county responsibility.

Who Maintains a Detention Pond in a Cobb Subdivision?

In the great majority of cases, the homeowners association does, or the individual lot owners do if there is no association. Detention and retention ponds built as part of a residential subdivision are typically private stormwater facilities located within a drainage easement, constructed by the developer as a condition of approval, and turned over to the association at buildout.

Why That Surprises People

A detention pond looks like public infrastructure. It sits in common area, it serves the whole neighborhood, and it exists because a government required it. None of that makes it county property. The obligation to inspect, mow, remove sediment, keep outlet structures clear, and eventually rehabilitate the facility usually sits with the association under its recorded declaration.

What That Costs

Routine maintenance is modest. Sediment removal, structural repair to an outlet or riser, and dam or embankment work are not. This is precisely the kind of expense that reveals underfunded association reserves, and it is why a buyer in a pond community should read the association's reserve study and recent meeting minutes rather than only the dues figure.

What Does a Drainage Easement Mean for a Lot Owner?

A drainage easement is a recorded right for water to be conveyed across a portion of your property, and usually a right for someone else to enter and maintain the conveyance. The land inside the easement is still yours. What you can do with it is limited.

Practical Restrictions

Easement language commonly prohibits construction, filling, grading, and other earth moving inside the easement area without written permission, and preserves the right of entry for inspection, maintenance, replacement, and repair. For a buyer, that translates directly into what cannot be built: a pool, a detached garage, an addition, a permanent shed, sometimes even substantial plantings, depending on the document.

Find It on the Plat

Drainage and utility easements appear on the recorded plat with their widths noted. This is one of several reasons a boundary survey is worth ordering during due diligence rather than skipping. If you are planning any structure in the rear yard, locate the easement before you locate the contractor.

What Should a Buyer Check on a Lot With Water on It?

Five things, none of which take long.

Where the Water Goes

Walk the lot after a heavy rain if you can, or at minimum look for the evidence: erosion channels, silt fans, standing water, a wet crawl space, or a sump discharge. Grading problems are cheaper to identify before closing than to argue about after.

Who Owns the Pipe

Ask directly: is the drainage system serving this lot public or private. A public system inside a dedicated right of way or county easement is maintained by the county. A private system inside a subdivision, including yard inlets and the pipes connecting them, generally is not.

Is an Association Responsible, and Is It Funded

If a pond or common drainage exists, request the recorded declaration, the current budget, the reserve study, and two years of meeting minutes. You are looking for two things: a clear statement that the association owns and maintains the facility, and evidence that it has money set aside to do so.

Any History of Failure

Ask the seller directly about flooding, standing water, erosion, sinkholes near an outlet, and any correspondence from the county or the association about drainage. In Georgia, sellers must disclose known latent defects, which are hidden problems a buyer could not find through a reasonably careful inspection. A drainage problem that only appears after sustained rain is a textbook example.

The Flood Map

Drainage and floodplain are related but not identical. A lot can flood without being in a mapped flood zone, and a lot can sit in a mapped zone and drain well. Check both. Buyers evaluating land conditions generally will find related considerations in our look at why the county line matters when you buy, since jurisdiction determines who regulates and maintains what.

How Cobb Handles Public Versus Private Systems

The general principle is straightforward even where the details vary by neighborhood. Drainage infrastructure that was dedicated to and accepted by the county, and that sits within a public right of way or a county-held easement, is county-maintained. Drainage that was built as part of a private development and never dedicated stays private, and the county's stormwater program does not take it over simply because a fee is now being collected. If you are unsure which category applies, the Cobb County Water System is the office to call with a parcel number, and the answer should be documented rather than remembered.

Why This Comes Up More Often Than It Used To

Much of Cobb's suburban housing stock is now thirty to fifty years old, which is roughly the service life of the original drainage infrastructure in a lot of those subdivisions. Corrugated metal pipe corrodes. Ponds silt in. Outlet structures clog and then wash out. Associations that were funded for mowing and a fresh coat of paint on the entrance monument were rarely funded for a pond rehabilitation, and that gap tends to surface as a special assessment rather than as a planned expense.

Selling a Home With a Pond, Creek, or Easement

Sellers in this position do better by leading with information than by hoping nobody asks.

Assemble the File

Pull the recorded plat showing easement locations, the association documents describing pond ownership and maintenance, any engineering or inspection reports on the facility, and receipts for drainage work you have done. Handing a buyer a documented answer converts an open-ended worry into a closed question.

Price and Position Honestly

A lot with a detention pond behind it is a different product than the same floor plan on an interior lot, and the market has already priced that difference into comparable sales. The right approach is a property-level market analysis against genuinely similar lots with full open-market exposure, rather than arguing the difference away. Sellers weighing pre-listing work should read our guide on renovating before selling a Marietta home.

Frequently Asked Questions

How much is the Cobb County stormwater fee? Residential customers pay a flat $4.75 per month. Non-residential customers are charged $4.75 per 3,700 square feet of impervious surface. The fee began June 1, 2026.

Who pays the Cobb stormwater fee? Customers in unincorporated Cobb County and the City of Mableton. Customers in other incorporated cities served by the Cobb County Water System are not charged it.

Who maintains a detention pond in a subdivision? Typically the homeowners association or the lot owners under the recorded declaration, not the county. Confirm ownership and maintenance obligations in the association's documents before you buy.

Can I build inside a drainage easement? Generally no. Easement language commonly prohibits construction, filling, and earth moving inside the easement area without written permission and preserves a right of entry for maintenance.

Conclusion

Water is the site condition that costs the most to fix and gets checked the least. The county's new fee funds the public system. Private ponds, private pipes, and easement areas remain private obligations, and the documents that define them are all available before closing. Read the plat, read the association file, and walk the lot after it rains.

Clareo Group, powered by The Agency Atlanta, builds drainage and easement questions into the due diligence calendar so a pond in the back yard is a known quantity rather than a surprise. Reach out and we will help you pull the plat and the association documents for the property you are considering.