Kirkwood Stormwater Ordinance: New Construction Permit Dates
October 8, 2026
October 8, 2026
On October 1, 2026, the Kirkwood City Council passed amended Bill 11148 on final reading with all seven members voting yes. The bill rewrites the city's infill development stormwater ordinance. Later the same evening, council adopted a revised stormwater manual through Resolution 98-2026. Both were amended to take effect on April 1, 2027. When a project goes under the new rules depends on when its permit application is filed. Closing dates, demolition dates and groundbreaking dates have no bearing on it.
That one detail changes how any Kirkwood house sold over the next six months gets priced, negotiated and scheduled. This applies most to an older house on a lot a builder might want.
The city's own guidance says the revised rules apply only to permit applications submitted after the effective date. Projects that are already permitted, under active review, or moving through the Architectural Review Board process stay under the rules that were in place when they were submitted, for as long as the permit lasts.
During the October 1 debate, council heard the same point stated directly. Applicants "need to apply for the permit by that date. They don't need a construction by that date." The council member who proposed moving the date to April 1 said it matched what the Home Builders Association had asked for: a six-month window to get permits in place. He said it also tells an owner who wants to sell that they have six months before the new requirements apply. Another member objected that the window gives people "a six months running head start" to avoid the mitigation the ordinance is meant to require. The amendment passed. Council Member Burkett, Council Member Lavender and Mayor Gibbons voted against it.
Staff told council they believe applications have already gone up as builders prepare for the change. That was a staff impression shared at the meeting, not a published count. It still shows how people are behaving. Builders are treating April 1 as a filing deadline.
Teardown pressure in Kirkwood is not hypothetical this year. In May 2026, a Kirkwood house was demolished.
For a buyer planning to build, the April 1 date means a property can be worth different amounts depending on the calendar. Someone who closes in January has roughly two months to get a complete application into the system under the current rules. Someone who closes in late March may not make it. A house sold to an owner-occupant who plans to add on later is in the same position: any project filed after April 1 is designed under the new limits.
This doesn't mean every older house is a teardown, and the ordinance doesn't set prices. It does mean a seller and a buyer planning work should both be clear, before signing, about which set of rules the buyer is counting on. That affects:
These requirements are what a buyer is trying to avoid by filing early, and what anyone filing later has to plan for. The comparison below uses the bill text presented to council in September, the work-session minutes, and the amendments passed on September 17 and October 1.
| Requirement | Current rules | Projects filed under the new rules, effective April 1, 2027 |
|---|---|---|
| Mitigation trigger for added impervious area | 1,000 sq ft of net additional impervious area | 750 sq ft in the September bill text |
| Lots over 25% impervious coverage | Treatment required | Treatment still required, with a small-project exemption described below |
| Rainfall to capture | First 1.14 inches | First 1.25 inches |
| Maximum impervious coverage, single-family lot | Not in the current stormwater requirements | 55% of the lot |
| Maximum impervious coverage, multifamily lot | Not in the current stormwater requirements | 85% of the lot |
| Basement depth on new homes and extensions | No citywide depth limit in the current requirements | 8 ft, or up to 9 ft with groundwater evidence |
| Grading permit for flatwork | Varies by source | None needed for 250 sq ft or less |
| Tree credit toward mitigation | 50 sq ft per qualifying tree | 150 sq ft per qualifying tree |
The city's earlier public summary listed the new mitigation trigger as 500 square feet. The bill text in the September 17 council packet sets it at 750. The final codified text of the amended bill had not been posted when this was written, so anyone pricing a project should confirm the figure with the city.
The basement rule changed twice before passage. Staff first tied basement depth to local groundwater, then proposed a flat 8-foot limit. On September 17, Emily Schwarz Post of the Home Builders Association asked council to keep 8 feet as the baseline but allow deeper basements when geotechnical work supports it. The amendment that passed allows up to 9 feet if a geotechnical report or the city's depth-to-water-table map shows the finished floor sits at least two feet above the seasonal high groundwater table. One council member who opposed it said the limits "could keep more homes affordable instead of tear downs and rebuilds."
Smaller changes also affect how a new house is designed. Side yards have to drain to the front or rear of the lot instead of across the property line. Sump pump overflows have to connect to the public MSD storm sewer when an inlet is on the property or in the right-of-way in front of it, and discharge can't create a nuisance for neighbors, sidewalks or roads. The bill's escrow table lists a $5,000 residential site restoration escrow and a $1,000 stormwater BMP construction escrow, both fully refundable once final inspection is accepted.
Not every change targets builders. Under the current manual, a lot already above 25% coverage could rebuild existing surfaces without adding treatment as long as it added no net impervious area. Staff had proposed removing that exemption. On October 1, council kept it but capped it at 250 square feet of new construction. That covers a small patio rebuild and keeps the exemption from being used to repave a whole backyard. The council member who proposed it said the goal was for people "to be able to maintain, improve, um, and stay in the home that they're in."
A second amendment gives the Director of Public Services authority to waive parts of the infill requirements when the applicant shows site-specific circumstances. The waiver can't be based on cost, lot size or other hardship. Public Services Director Chris Krueger gave an example: widening one of Kirkwood's many 8-foot driveways by a foot or two without needing a BMP.
This part gets the least attention, and it already applies under the current rules. When Kirkwood requires a stormwater BMP, the owner signs a BMP Maintenance Agreement before a notary and the Assistant City Engineer. The agreement is recorded with St. Louis County, and the permit isn't released for construction until the city receives the recording receipt. The city inspects the BMP one year after construction and every three years after that, and property owners are responsible for maintaining it under the agreement.
Under the new manual, trees counted toward mitigation are also listed on that recorded agreement. They have a 10-foot protection radius where no impervious surface or construction is allowed, and they are inspected along with the other BMPs. If a recorded tree dies or is removed, the owner may face enforcement and has to provide replacement treatment. That can mean two new trees of at least 2-inch caliper for each tree lost, other protected trees on the lot, or another BMP.
For a buyer, these obligations come with the house. Reviewing the title commitment for a recorded BMP Maintenance Agreement, finding out where the rain garden or drywell is, and asking for the most recent inspection records are all reasonable steps on any Kirkwood home built under these rules.
Does the ordinance affect me if I'm just selling my house as it is? Not directly. The city says routine maintenance isn't affected and most lots are well under the 55% cap. The indirect effect is on your buyer pool. A buyer who plans to build or expand has a reason to care about when they can file a permit application.
Do stormwater fees change? The city says the revisions don't change the current fee structure.
Who can answer a question about a specific lot? Assistant City Engineer Jennifer Brown handles technical questions about the ordinance at [email protected] or 314-822-5846. This post is general information, not legal or engineering advice. You can watch the full October 1 debate on the city's council meeting video and read the city's stormwater ordinance page.
If you're thinking about selling an older Kirkwood home this winter, or buying one to rebuild or expand, the April 1 filing date should shape your contract timeline from the first offer. Susan Hurley Homes can help you set a listing or purchase schedule around Kirkwood's permit calendar. Request a Complimentary Consultation.
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