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 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).
There are several requirements imposed on Gilbert by the permit including having a Stormwater Management Plan (SWMP). Gilbert is required to prohibit non-stormwater discharges into the storm sewer system and to implement enforcement procedures.
The SWMP also mandates that Gilbert require construction sites to:
- implement erosion, sediment, and waste control measures
- address post construction runoff from new development and redeveloped projects
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 measureable 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