Champaign, IL Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing article
- City Code Ch. 29.5, Art. IV, § 29.5-4.04
- Nonresidential detention trigger
- Over 2 acres (or smaller if >50% impervious)
- Residential detention trigger
- Over 5 acres (or smaller if >50% impervious)
- Peak discharge cap
- 0.18 cfs per acre for the 100-year, 24-hour storm
- General duty
- All new development must provide detention, § 29.5-1.10
- Enforcing official
- City Engineer, § 29.5-2.20
Summary
Champaign requires on-site stormwater detention for nonresidential development over 2 acres and residential development over 5 acres, or any smaller site over 50% impervious. Drainage systems must hold the peak 100-year discharge to no more than 0.18 cfs per acre.
(a)Developments initiated after the adoption of these regulations shall provide for temporarily detaining stormwater runoff from the site in the following cases:(1)In any nonresidential development of greater than two (2) acres, including one-half of existing, adjacent streets, or less than two (2) acres if more than fifty (50) percent of the surface area is impervious.(2)In any residential development of greater than five (5) acres, including one-half of existing, adjacent streets, or less than five (5) acres if more than fifty (50) percent of the surface area is impervious.(3)In any other development, if the City Engineer determines that the development needs detention to prevent its doing harm.(b)The drainage system for a development shall be designed to control the peak rate of discharge from the property for the 100-year, 24-hour event to levels which will not cause an increase in flooding or channel instability downstream when considered in aggregate with other developed properties and downstream drainage capacities. The peak 100-year discharge shall not be greater than 0.18 cfs per acre of property drained.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 80).
Full Breakdown
5, Article IV (Drainage System Designs) sets the city's core stormwater engineering standard. 04 requires temporary detention of runoff for any nonresidential development greater than two acres (including half of adjacent existing streets), or a smaller nonresidential site if more than 50 percent of its surface is impervious; the residential trigger is five acres under the same impervious-surface exception. The City Engineer can also require detention on any other development found to need it to prevent harm. 18 cfs per acre of property drained; a detailed watershed study can modify that release rate.
10 backs this with a general requirement that all new development and redevelopment, including projects by governmental agencies and nonprofits, provide stormwater detention consistent with Article IV, and that engineering drawings for subdivisions, manufactured home parks, commercial and planned developments carry a professional engineer's signed statement confirming they account for changes in surface water drainage. 01: minimize impervious surface, use vegetated swales and natural depressions, then detention structures, and only then storm sewers and channels.
Violations & Fines
The City Engineer serves a written notice of violation on anyone responsible for drainage improvements built contrary to approved plans or permit conditions, and can issue a stop-work order under Section 29.5-2.20. A complaint may be filed in Circuit Court, with a fine up to the maximum set in Section 1-21 of the Municipal Code and each day of the violation treated as a separate offense; the City Attorney may also seek a restraining order or injunction under Section 29.5-2.21.
Frequently Asked Questions
Does my Champaign development need a stormwater detention basin?
How much stormwater can a Champaign site release downstream?
Who signs off on Champaign drainage plans before construction?
Sources & Official References
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