Do I Need Stormwater Detention for My Development in Waco? Here's What the City Actually Says

If you've called our office about a new development project in Waco, there's a good chance this question came up early in the conversation: "Why does the City require stormwater detention, and is there any way around it?"

It's one of the most common questions we field — multiple times a week. And honestly, the answer isn't buried in some obscure administrative code. It's plainly stated in a single City document: the City of Waco Stormwater Design Criteria (January 2025). In this post, I'm going to walk you through exactly what that document says, where to find it, and what it means for your project.

Why Does Waco Require Detention in the First Place?

When land is developed — whether you're paving a parking lot, building a strip center, or putting in a subdivision — impervious surfaces replace grass and soil. Rain that used to soak into the ground now runs off faster and in greater volume. That increased runoff has to go somewhere, and without controls, it goes downstream onto someone else's property.

The City of Waco's Stormwater Management Policy exists to prevent exactly that. Section 9.1 of the Stormwater Design Criteria states the purpose clearly:

"The purpose of a stormwater detention facility is to store excess stormwater runoff (resulting from land development) and to discharge it at a pre-determined release rate. Typically, release rates from a detention facility are designed such that the stormwater discharge rates from a developed site will be limited to those that existed prior to any land development activities."

In plain terms: your developed site should drain no faster than it did before you built anything on it.

The Core Rule: Section 1.7(B)(1)

The fundamental detention requirement is spelled out in Section 1.7(B)(1) – Provision for Stormwater Detention:

"Post-development peak stormwater flowrates shall not be increased at any point downstream from the development of land for the 2-year, 25-year, and 100-year storm frequencies."

This applies to all three standard design storm events — not just the big one. That's a common misconception. The City requires you to match pre-development flow rates across the board: the 2-year (frequent, moderate rain events), the 25-year, and the 100-year (major flood events).

This same standard is repeated in Section 9.1 under the Stormwater Detention Facilities chapter, reinforcing that it isn't just a policy statement — it's a design requirement enforced through the engineering review process.

So When Is Detention Not Required?

This is where most of the conversation happens. The same section — Section 1.7(B) — lays out three legitimate paths to avoid or reduce detention.

1. Single Residential Structure on One Lot

The simplest exemption is this sentence from Section 1.7(B)(1):

"Stormwater detention will not be required for the construction of a single residential structure on one single-family lot."

If you're building one house on one lot, you're exempt. Full stop. This is the only blanket, no-questions-asked exemption in the document.

2. Fee-in-Lieu of Detention — Section 1.7(B)(2)

Under Section 1.7(B)(2) – Provision for Fee-in-Lieu of Stormwater Detention, the City may waive the detention requirement if the developer can demonstrate "No Adverse Impact" through one or more approved mitigation measures. The document lists three options:

• Monetary contribution — A fee paid into the City's Municipal Drainage Utility System account, calculated based on the increase in impervious area. This must be paid before any development permits are issued.

• Land dedication — Donation of privately owned land or a permanent easement adjacent to a stream corridor for drainage improvements or preservation. Value must equal or exceed the City's fee schedule.

• In-kind contribution — Construction of a stormwater management facility on a separate, existing property that currently lacks adequate drainage controls. This must be completed and accepted by the City before final inspection of your development.

Important caveat: the fee-in-lieu option also requires that the 100-year peak discharge can be conveyed to a receiving water body without creating adverse impacts. You can't just write a check and walk away if the downstream system can't handle the flow.

3. Director Waiver — Section 1.7(B)(3)

Section 1.7(B)(3) – Provision for Waiving Stormwater Detention gives the Public Works Director authority to waive detention entirely, but the bar is specific:

"Such a waiver may be granted if the development is adjacent to a receiving major watercourse (Lake Waco, Lake Brazos, Brazos River, or the North, South, or Middle Bosque Rivers) and a conveyance drainageway, channel, culvert, etc. can be designed and constructed to discharge the 100-year design storm directly into the receiving lake or river."

This is a narrow exemption. Your project needs to be directly adjacent to one of the named major water bodies, and you still need to engineer a compliant conveyance path. For most commercial and residential developments in Waco, this won't apply — but for projects near the Brazos River corridor or Lake Waco, it's worth exploring.

The Bottom Line for Waco Developers

Here's how I summarize it for clients:

• Commercial development, multi-lot subdivisions, and most residential projects: Detention is required. Plan for it early and size your pond lot accordingly.

• Single house on a single lot: No detention required.

• Fee-in-lieu: Available if the City agrees and the downstream system can handle the flows. Requires payment before permits.

• Director waiver: Available only for sites directly adjacent to major named water bodies with a direct discharge path.

All of this comes directly from the City of Waco Stormwater Design Criteria, January 2025 edition — specifically Sections 1.7(B) and 9.1. If you're working on a project and have questions about how these rules apply to your specific site, that's exactly what we're here for.

Whether you're in the early stages of evaluating a site or already working through the permitting process, stormwater detention is one of those requirements that can significantly affect your site layout, budget, and timeline if it catches you off guard. At Merritt Engineering Services, we work with developers, property owners, and contractors across the Waco area every day on exactly these questions. Give us a call before you get too far down the road — we can help you understand what's required for your specific property and find the most practical path forward. To see examples of our drainage and land development work, visit our project portfolio.

Merritt Engineering Services, LLC | TBPE Firm F-23159 | (254) 709-5720 | MerrittEngineeringServices.com