Mount Prospect, IL Environmental Rules: Flood Zones (2026)
FEMA flood zone rules in Mount Prospect, IL, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.
Key Facts
- Permit issued by
- Director of community development
- Compensatory storage
- At least 1.5 times the volume of storage lost
- Mapped streams
- Des Plaines River, Feehanville Ditch, McDonald Creek, Weller Creek
- FEMA study date
- Cook County flood insurance study dated August 19, 2008
- Correction window
- 10 days after written notice
- Shed and garage exception
- Under $5,000 value and under 500 square feet
Summary
In the Village of Mount Prospect, no one can start development in a special flood hazard area without a development permit from the director of community development. Fill in the flood fringe requires compensatory storage, and the mapped SFHAs include the Des Plaines River, Feehanville Ditch, McDonald Creek and Weller Creek.
Development in and/or filling of the flood fringe will be permitted if protection is provided against the base flood or 100-year frequency flood by proper elevation, and compensatory storage and other provisions of this article are met. No use will be permitted which adversely affects the capacity of drainage facilities or systems. ... ... A. Development Permit: No person, firm, corporation, or governmental body not exempted by state law shall commence any development in the SFHA without first obtaining a development permit from the director of community development. ... ... 2. Compensatory Storage: Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood or 100-year frequency flood elevation.
Full Breakdown
Chapter 22 of the Village Code is the floodplain ordinance for the Village of Mount Prospect. Section 22.101 states that it is enacted to maintain the Village's eligibility in the national flood insurance program and to keep new development from increasing flood or drainage hazards to others. The director of community development administers it under section 22.104: checking new development sites against special flood hazard area (SFHA) designation, referring floodway projects to a registered professional engineer under contract to the village, requiring all other federal, state and local permits before a floodplain development permit issues, and inspecting projects before, during and after construction.
Section 22.105 ties the mapped SFHAs to the Des Plaines River, Feehanville Ditch, McDonald Creek, McDonald Creek Tributary B and Weller Creek, using the flood insurance study of Cook County prepared by FEMA and dated August 19, 2008.
For the flood fringe, section 22.106 permits development or filling only if protection against the base flood is provided by proper elevation, and compensatory storage and the article's other provisions are met. The application goes on a form from the director and must carry scaled site drawings showing property line dimensions and legal description, sealed by a licensed engineer, architect or land surveyor, with existing grade elevations, all changes in grade, and the location and dimensions of buildings. A soil erosion and sedimentation control plan is required for disturbed areas. If fill raises the site above the base flood elevation, the applicant must obtain a letter of map revision (LOMR) from FEMA. The excavation for compensatory storage must be at least equal to one and one-half (1.5) times the volume of storage lost, and storage lost below the existing 10-year flood elevation is replaced below the proposed 10-year flood elevation.
Section 22.109 adds public health standards: no chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants or other hazardous or toxic materials below the flood protection elevation. Toolsheds and detached garages on an existing single-family platted lot can sit below that elevation only if the building is not used for human habitation, is valued at less than five thousand dollars ($5,000.00), and is less than five hundred (500) square feet in floor size.
Violations & Fines
Under section 22.113, failure to comply with a permit or variance condition is a violation. If the owner fails after ten (10) days' notice to correct it, the village can seek a circuit court injunction, the violator is fined per appendix A, division III, each day is a separate offense, and the village can record a notice of violation on the property title. The director also informs the owner that the violation is considered a wilful act to increase flood damages.
Frequently Asked Questions
Do I need a permit to build in a floodplain in the Village of Mount Prospect?
How much compensatory storage does fill require?
Can I build a detached garage below flood level?
What happens after a floodplain violation notice?
Sources & Official References
Other rules in Mount Prospect
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Flood Zones in Nearby Cities
How other cities in Cook County handle flood zones.