Gilbert, AZ Environmental Rules: Stormwater Management (2026)
Key Facts
- Ordinance
- Ordinance 1590. Stormwater Management
- State Permit
- AZPDES construction general permit
- Trigger
- 1 acre or more of land disturbance
- Retention
- On-site retention required for new development
- Climate
- Monsoon storms create flash flood risk
Summary
Gilbert enforces stormwater management through Ordinance 1590 and the Arizona Pollutant Discharge Elimination System (AZPDES). Construction sites disturbing one acre or more must obtain coverage under the construction general permit. The Sonoran Desert environment makes stormwater retention critical due to flash flood risks from monsoon storms. Gilbert requires on-site retention for new development to manage runoff.
Municipal Separate Storm Sewer (MS4) Permit. The Clean Water Act (CWA), among other things, regulates stormwater and urban runoff to protect water quality. The Phase II Final Rule requires small municipal separate storm sewer systems (MS4s) such as Gilbert to obtain a National Pollutant Discharge Elimination System (NPDES) permit which specifies the measures that will be taken to prevent pollution from entering the storm system. In Arizona, Phase II permits are administered by the Arizona Department of Environmental Quality (ADEQ). This permit requires the Town of Gilbert to prohibit non-stormwater discharges into the storm sewer system and perform enforcement response through the implementation of a Stormwater Management Plan (SWMP). In order to meet these requirements, the Gilbert Town Council adopted Ordinance 1590 on August 3, 2004. The SWMP includes six Minimum Control Measures with best management practices (BMPs) and measurable goals for each: Public Education and Outreach; Public Participation/Involvement; Illicit Discharge Detection and Elimination; Construction Stormwater Runoff Controls; Post Construction Stormwater Management; Pollution Prevention.
Full Breakdown
Gilbert enforces stormwater management regulations to prevent flooding and protect water quality. New construction and major renovations must include stormwater management plans. Impervious surface limits may apply in residential zones. Low-impact development techniques like rain gardens, permeable pavers, and bioswales are encouraged or required. Erosion and sediment control plans needed during construction. Post-construction stormwater facilities must be maintained by property owners. Municipal separate storm sewer system (MS4) permits govern city-wide discharge.
Frequently Asked Questions
When is stormwater coverage required in Gilbert?
Why is stormwater management important in Gilbert?
Sources & Official References
Other rules in Gilbert
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Stormwater Management in Nearby Cities
How other cities in Maricopa County handle stormwater management.