Who Regulates Stormwater in San Antonio? A Jurisdiction Map

Published September 21, 2026. Last reviewed September 21, 2026. Technical review: Jim Price, CISEC, CESSWI. Founder, Stormwater Compliant LLC.

Seven bodies touch stormwater in the San Antonio metro. TCEQ runs the state construction permit and the Edwards Aquifer overlay. SAWS, the City of San Antonio, and TxDOT are MS4 co-permittees. Bexar County Public Works regulates post-construction in the unincorporated area. The San Antonio River Authority and the Edwards Aquifer Authority have narrower roles.

Nobody publishes this map, so here it is.

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The seven bodies, mapped

Body	What it actually controls	Where	What you send them
TCEQ, stormwater program	The construction general permit TXR150000, and the industrial MSGP	Statewide	NOI, NOC, NOT via STEERS
TCEQ, Edwards Aquifer Protection Program	Construction and water quality over the aquifer, under 30 TAC Chapter 213	Recharge, Transition, and Contributing Zones	WPAP or CZP, plus geologic assessment
SAWS	Local enforcement of TPDES construction requirements as MS4 co-permittee; Recharge Zone inspections	City of San Antonio service area	NOI or Construction Site Notice, 48 hours ahead
City of San Antonio	Site design and drainage under UDC 35-504; Chapter 34 of the City Code; MS4 permittee under TPDES WQ0004284000	Inside city limits, with ETJ implications	Drainage and detention design through development review
Bexar County Public Works	Post-construction storm water control measures	Unincorporated Bexar County	Post-construction permit application, review, engineer certification
TxDOT	Work in state right of way; MS4 co-permittee	State highway ROW	Permits for ROW work
Edwards Aquifer Authority	Groundwater use. Pumping, wells, withdrawal rights	Portions of eight counties	Well and withdrawal permits, not construction plans

Plus one body that regulates nothing here but matters anyway: the San Antonio River Authority, which administers the structural BMP maintenance certification Bexar County accepts, and runs the region's Low Impact Development program.

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The two Edwards Aquifer organizations

If this article resolves one thing for you, let it be this. Two organizations have "Edwards Aquifer" in their remit and they do entirely different jobs.

TCEQ's Edwards Aquifer Protection Program regulates water quality and construction activity over the aquifer under 30 TAC Chapter 213. This is the body that reviews and approves your Water Pollution Abatement Plan or Contributing Zone Plan. Under Part II.C.5 of the state construction permit, you cannot commence construction until they approve it.

The Edwards Aquifer Authority (EAA) regulates groundwater use: pumping, well permits, and withdrawal rights across portions of eight counties, being Bexar, Comal, Hays, Caldwell, Guadalupe, Medina, Uvalde, and Kinney.

For a construction project, your agency is TCEQ. The EAA does not review your basin design, does not approve your WPAP, and cannot help with your development schedule. They are a groundwater management district, not a construction regulator.

The reverse also holds. If you are drilling a well or need withdrawal rights, TCEQ's Edwards Aquifer Protection Program is not your agency.

Full detail on the plans themselves is in Edwards Aquifer Protection Plans: WPAP and CZP basics.

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Why SAWS and the city are both involved

The second most common confusion, and it has a clean explanation.

The federal stormwater program requires operators of municipal separate storm sewer systems to hold a permit and run a stormwater management program. In this region, the MS4 permit is held jointly. The City of San Antonio holds TPDES Permit WQ0004284000, and SAWS and TxDOT are co-permittees.

Co-permittee means shared responsibility for the program, with the parties dividing the work. In practice, SAWS carries much of the construction stormwater enforcement, under the City's construction stormwater ordinance 2014-06-19-0472, approved by City Council on June 19, 2014.

So the division looks like this:

• The City owns the development review side: platting, drainage design, detention under the UDC, and Chapter 34 of the City Code.
• SAWS owns much of the field enforcement side: notification, inspections, and construction compliance. They also inspect quarterly over the Recharge Zone within COSA jurisdiction to verify WPAP compliance.
• TxDOT covers state right of way.

It is not duplication. It is one permit with the work split. More in the SAWS construction stormwater ordinance.

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Determining your boundaries

Three boundary questions, in order of how often they get answered wrong.

Are you inside the city limits? This determines whether the UDC and SAWS apply, or whether Bexar County's post-construction program does. San Antonio's annexation history is complex, its ETJ is large, and adjacent parcels genuinely do fall differently. Do not infer this from the mailing address. A San Antonio postal address does not mean you are inside the city limits.

Which Edwards Aquifer zone, if any?

• The Recharge Zone is where the aquifer's water-bearing formations crop out and water enters directly, through caves, sinkholes, faults, and fractures.
• The Transition Zone sits downgradient of the recharge area.
• The Contributing Zone is the upstream catchment whose precipitation flows downgradient toward the recharge zone.

These are mapped lines, not judgment calls. TCEQ publishes an Edwards Aquifer Map Viewer, and the zone is determined by the official map, not by what the site looks like. A flat suburban parcel can sit squarely on the Recharge Zone.

Which watershed and receiving water? This determines your outfall, which MS4 operator receives your discharge, and whether the receiving segment is impaired.

A site can be inside the city, over the Recharge Zone, and draining to an impaired segment. That combination triggers more requirements than any single check would reveal, which is exactly why all three have to be checked.

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Not regulators, but they still matter

San Antonio River Authority (SARA). SARA does not issue your construction permit, but it administers the training and certification program for structural BMP maintenance that Bexar County requires of maintenance providers on permitted post-construction BMPs. It also runs the region's Low Impact Development program, including design guidance and credential courses. If you own a permitted BMP in the unincorporated county, SARA's certification is what your maintenance provider needs to hold.

TxDOT. A co-permittee on the MS4 and the controlling authority for work in state right of way. Projects with a driveway connection, a utility crossing, or drainage discharging into a state highway ditch acquire a TxDOT dimension that is easy to miss until the review.

The EPA. Texas is a delegated state, so EPA does not run day-to-day stormwater permitting here. It retains authority to act directly, which is rare but not theoretical.

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Who to call about what

Your question	Who
Do I need a state construction permit, and how do I file?	TCEQ stormwater program, via the construction stormwater page
Is my site over the aquifer, and what plan do I need?	TCEQ Edwards Aquifer Protection Program. San Antonio Regional Office, covering Comal, Bexar, Medina, Uvalde, and Kinney counties: (210) 490-3096
Construction stormwater notification and inspection inside the city	SAWS: stormwaterconstruction@saws.org
Detention sizing, drainage design, platting inside the city	City of San Antonio development review, under UDC 35-504
Post-construction permit in the unincorporated county	Bexar County Public Works
BMP maintenance certification	San Antonio River Authority
Work in state right of way	TxDOT area office
Well permits or groundwater withdrawal	Edwards Aquifer Authority

Where we have not published a direct number above, it is because we could not verify a current one. Use the agency page rather than a number from a third-party directory, which in our experience is wrong often enough to matter.

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Common jurisdiction mistakes

Assuming a San Antonio address means city jurisdiction. Large areas of Bexar County carry San Antonio mailing addresses and are unincorporated. The county's post-construction permit applies there, and the UDC does not.

Calling the Edwards Aquifer Authority about a construction plan. Covered above. It costs a day.

Treating SAWS and the City as interchangeable. They divide the work. Sending the drainage design to SAWS and the construction notification to the City wastes both.

Assuming the Edwards zones follow visible terrain. They are mapped. Check the map.

Missing TxDOT. A driveway onto a state highway or a discharge into state ROW brings TxDOT in, and finding that out at review is a delay.

Assuming one approval covers another. A SWPPP does not satisfy the Edwards Aquifer requirement. Edwards approval does not satisfy Bexar County's post-construction permit. Each is separate. See our field guide to the TCEQ Construction General Permit for the state layer, and Bexar County post-construction permits for the county layer.

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Tell us the address and we will tell you who has a claim

You do not need to work this out yourself. Send us the project address and we will come back with which jurisdictions apply, whether the parcel sits over the Recharge, Transition, or Contributing Zone, what each authority requires, and in what order.

It costs nothing and it takes us an afternoon. If a 120-day Edwards Aquifer review belongs in your critical path, better to know now.

Request a quote or call (210) 776-6515. The full local picture is in San Antonio, Bexar County, and Edwards Aquifer stormwater rules, and our services start with SWPPP preparation.

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Sources

• TCEQ, Stormwater Permits and the Edwards Aquifer
• TCEQ, Edwards Aquifer Protection Program
• TCEQ, Stormwater General Permit for Construction Activities
• Bexar County, Post-Construction Permits
• SAWS, Aquifer Protection and Evaluation
• San Antonio River Authority, Low Impact Development
• City of San Antonio, 2022 Stormwater Management Plan, TPDES Permit WQ0004284000 (PDF)