Last Updated 08/12/2026
STORMWATER DETENTION
Requirements
(a) A combination of stormwater detention and controlled release rates for stormwater runoff is required for all new construction, additions to existing structures or appurtenances, and any additional development or change or use which will increase the volume of stormwater runoff over that which existed prior to the proposed development. Such detention and release rate shall be calculated in accordance with the procedures accepted by the Metropolitan Water Reclamation District of Greater Chicago and from time to time amended. Each development under this article shall discharge stormwater at the specified release rate into an existing or proposed natural stormwater outlet. All plans, calculations and specifications shall be subject to the review of the town engineer and shall receive his approval prior to commencement of any construction.
(b) The release rate of stormwater runoff for new construction shall not exceed the volume of stormwater that would run off the entire subject site in its natural undeveloped state for a three-year rainfall intensity. For additions or change in use, stormwater detention will only be required for that portion of a parcel being developed and increasing the volume of stormwater runoff greater than the land in its natural, undeveloped state.
(c) The live detention storage to be provided under this article will be calculated on the basis of a 100-year frequency rainfall as published by the National Weather Service for this area and will have sufficient volume to handle the runoff for any and all durations from the parcel subject to the detention under this article.
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Frequently Asked Questions
When does a Cicero property need to provide stormwater detention?
Any new construction, addition to an existing structure, or change in use that increases the volume of stormwater runoff beyond what the site generated in its natural, undeveloped state triggers the requirement. For additions or a change in use, detention only applies to the portion of the parcel actually being developed and adding runoff, not the whole property. Every plan, calculation and specification has to go through the town engineer for approval before construction can start.
How is the required detention volume calculated in Cicero?
Live detention storage is sized using a 100-year frequency rainfall as published by the National Weather Service, and it has to hold enough volume to handle runoff across any duration of storm from the site. The release rate is a separate calculation: for new construction, it can’t exceed what the entire site would have shed in its natural, undeveloped state during a three-year rainfall event, using methodology set by the Metropolitan Water Reclamation District of Greater Chicago.
Where does detained stormwater ultimately go in Cicero?
The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
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