Meridian, ID Environmental Rules: Stormwater Management (2026)
Key Facts
- Applies to
- All subdivisions and site improvements
- Swale slope max
- 3:1 (horizontal:vertical)
- Drain-down window
- No standing water after 48 hours
- Controlling design manual
- ACHD Drainage and Stormwater Management Policy Manual
- Companion requirement
- Adequate storm drainage system citywide (§ 11-3A-18)
Summary
Every new development in Meridian must install an adequate storm drainage system built to the city's adopted standards, and subdivisions must integrate vegetated stormwater swales or green facilities into required landscaping.
A. Purpose. The regulations of this section are intended to improve water quality and provide a natural, effective form of flood and water pollution control through the integration of vegetated, well designed stormwater filtration swales and other green stormwater facilities into required landscape areas, where topography and hydrologic features allow. B. Applicability. The standards for stormwater integration shall apply to all subdivisions, site improvements and ACHD stormwater facilities. ACHD stormwater policy shall supersede city requirements for stormwater facilities.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 14).
Full Breakdown
Meridian requires an adequate storm drainage system in every development, built to the city's adopted standards using Best Management Practice (UDC section 11-3A-18). Subdivisions and site improvements must also integrate stormwater into required landscape areas: vegetated filtration swales, slopes no steeper than 3:1, and free-draining design with no standing water 48 hours after a storm event (section 11-3B-11). Ada County Highway District's Drainage and Stormwater Management Policy Manual supersedes city requirements for the facilities themselves, though facilities counted toward open space must still meet city standards.
Violations & Fines
Development plans lacking an adequate approved drainage system, or landscape plans skipping required stormwater integration, are rejected by the Planning Division during site plan and subdivision review.
Frequently Asked Questions
Does Meridian or Ada County Highway District control stormwater facility design?
What stormwater design is required in Meridian's required landscape areas?
Sources & Official References
Other rules in Meridian
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Stormwater Management in Nearby Cities
How other cities in this county handle stormwater management.