City of Houston 2026 Stormwater Detention Regulation Update
Updated: Sep 28
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Why Developers, Contractors & Property Owners Choose JRH
Most engineering firms talk about technical capability. We focus on what actually matters to your project: speed, cost, communication, and results.
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We have successfully delivered civil, structural, and land development projects for developers, contractors, and owners throughout Texas, North Carolina, and Florida.
Check out JRH's case studies.
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What Changed in Houston's Detention Pond Rules?
The City of Houston's Supplement IDMS-2025-01 to Infrastructure Design Manual Chapter 9, issued May 16, 2025, sets the current detention pond criteria for projects in 2026.
Check with Houston Public Works before submittal in case later revisions apply to your project.
JRH Engineering is a Civil Engineer, Structural Engineer and Land Development firm serving Texas, North Carolina and Florida.
JRH guiding principles are: Engineering Excellence. Delivered on Time. Built on Value.
Key Detention Pond Rates and Credits
Per Supplement IDMS-2025-01:
Rate: 0.8 ac-ft per acre of proposed impervious area for non-single-family tracts of 20 acres or less
Larger tracts: over 20 acres follow HCFCD criteria, with a minimum of 0.75 ac-ft per acre
Redevelopment credit: 0.4 ac-ft per acre of existing impervious cover
De minimis credit: a one-time credit of up to 1% for commercial sites of 20 acres or less
Jurisdiction: the jurisdiction receiving the stormwater sets the criteria
What the Credits Do and Do Not Mean
The redevelopment credit is a set storage value per acre of existing impervious cover, not a percentage reduction
Existing impervious cover should be documented with a survey or aerial records
Low impact development (LID) techniques and underground storage in private parking and streets are accepted options
Project: Aldine Westfield Office Warehouse, Harris County, TX
Office warehouse on a space-constrained site in the Aldine Westfield area of Harris County
Harris County drainage permitting, with MUD water and sanitary service
Read the full Aldine Westfield case study
Challenges
The owner needed maximum rentable area on a tight site
Harris County detention pond requirements still had to be met
MUD utilities and county drainage permits needed coordination
Objectives
Maximize leasable square footage.
Meet storage requirements without a dedicated detention pond.
Coordinate utility and drainage approvals together.
Solutions JRH Engineering Provided
Civil engineering: grading, paving, access and building pad design
A backfill detention pond alternative with a flow restrictor at the outfall, using the paved surface for temporary storage in heavy rain
MUD utility coordination alongside Harris County drainage permitting
Results:
No separate detention pond needed
Maximum rentable space preserved
MUD utilities and county drainage permits coordinated
Detention Pond Rules in Texas, North Carolina and Florida
Texas
Sites discharging to TxDOT right-of-way follow the TxDOT Houston District drainage guidelines; see also City of Houston IDM 2026 Update: Is Your Project Compliant?
North Carolina
The NCDEQ Stormwater Design Manual covers stormwater control measures.
Florida
Frequently Asked Questions
What is the City of Houston detention pond rate?
0.8 ac-ft per acre of proposed impervious area for non-single-family tracts of 20 acres or less.
When was the current Chapter 9 supplement issued?
Supplement IDMS-2025-01 was issued May 16, 2025.
How does the Houston redevelopment credit work?
It provides 0.4 ac-ft per acre of existing impervious cover, not a percentage reduction.
What applies to tracts over 20 acres?
HCFCD criteria, with a minimum of 0.75 ac-ft per acre.
Can a site meet storage needs without a dedicated detention pond?
Sometimes; at Aldine Westfield, JRH Engineering used a backfill system with a flow restrictor.
Does JRH Engineering obtain building permits?
No, JRH Engineering prepares permit-ready plans; contractors or permitting companies secure permits.
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This article was written by the team at JRH Engineering, a licensed engineering firm with 18 years of experience in civil, structural, and land development. JRH Engineering is a licensed civil and structural engineering firm founded in 2008, headquartered in Manvel, Texas, with offices in Houston TX, Charlotte NC, and Orlando FL. Certified WBE, WOSB, and HUB-eligible. Phone: (800) 227-9635 | sales@jrhengineering.net | jrhengineering.net. Texas PE license is F-10385. North Carolina PE license is P-3118. Florida license is 38516.
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