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Key Regulatory and City of Houston Detention Updates That Could Benefit Your Development
Big news on two fronts for developers and engineers—recent updates at both the federal level and within the City of Houston are reshaping how projects approach permitting, drainage, and wetland impacts. Whether you’re navigating Clean Water Act requirements or sizing stormwater detention, these changes offer new flexibility, potential cost savings, and clearer compliance pathways.
Our team has put together a brief summary of these important changes to keep you informed. If you’d like to schedule a presentation to discuss how these updates may impact your projects, please click here to schedule a presentation with WGA, and one of our team members will be in touch to coordinate a time.
Houston Simplifies Detention Requirements with Chapter 9 Supplement!
The wait is over—Houston has officially adopted a supplement to Chapter 9 of the Infrastructure Design Manual (IDM), delivering long-anticipated relief for development and redevelopment projects.
Here’s what developers and consultants need to know:
- Simplified Flat Detention Rate – Projects under 20 acres now follow a simplified detention rate of 0.80 ac-ft/ac. No more curve table or sliding scale!
- Redevelopment Credit – Sites under 20 acres get credit for existing impervious cover at 0.40 ac-ft/ac, making redevelopment more feasible.
- De Minimis Exception – Small commercial improvements (awnings, grease traps, EV chargers, additional floors) can increase impervious cover by up to 1% without triggering detention—one-time per property. Disturbed areas still follow the redevelopment detention rate.
- Legacy Projects Preserved – Master-planned developments with approved drainage plans can continue under their original criteria.
- Jurisdiction-Based Criteria – Clarified guidance ensures designers apply detention requirements based on the appropriate jurisdiction.
- Defined Exemptions – Clearer criteria for when detention is not required, streamlining planning efforts.
Regulatory Update: New WOTUS Guidance – What Developers Need to Know
Federal wetland rules have changed following the Sackett v. EPA ruling, with major implications for Clean Water Act (CWA) permitting.
Key Changes at a Glance:
- Clarified “Continuous Surface Connection” – Only wetlands and streams with a direct, visible connection to relatively permanent waters (rivers, lakes, oceans) now count as Waters of the United States (WOTUS).
- Narrower Federal Jurisdiction – Isolated wetlands and ephemeral streams (that flow only after rain) are no longer federally regulated under CWA Section 404.
- USACE Resumes Determinations – The Army Corps of Engineers is issuing determinations using this narrower standard. Public input is ongoing, and updates are possible.
- State and Local Collaboration – With fewer waters federally regulated, state, tribal, and local governments may step in to regulate sensitive areas.
What This Means for Developers:
- Fewer Federal Permits Required – Projects impacting non-connected wetlands/streams may avoid Section 404 permits, reducing timelines and costs.
- Increased State Oversight – Some states may introduce or enforce stricter local rules.
- Regulatory Shifts Ahead – Further refinements may follow based on public feedback.
- Environmental Scrutiny – Projects in sensitive areas may face more local or community attention due to the reduction in federal review.
Bottom Line
These updates—at both the city and federal levels—could significantly reduce permitting barriers and make redevelopment more attainable, especially on smaller sites. However, local rules are likely to evolve in response to federal changes, and coordination with state and municipal agencies remains critical.
We’re here to help! If you’d like a presentation on how these updates affect your development projects, click here to schedule a session with our team!