Stormwater Quality Program
1001 N Central Ave.
Phoenix, AZ 85004
To report a problem or file a complaint:
Environmental Services Department
Maricopa County Stormwater Management and Discharge Control Regulation
Waste Resources and Recycling Management
Maricopa County is located in central Arizona in the Sonoran Desert, which is characterized by long, hot summers and short, mild winters. Precipitation in the County averages approx. 7 inches per year (based on 50 years of rainfall data), and falls primarily during the summer monsoon season and during winter storms. With approximately 3.2 million residents, it is the most populous county in the state and the fourth most populous county in the United States, according to the 2000 U.S. census. The County’s area is 9,226 square miles, of which 1,441 are incorporated and 7,785 are unincorporated. Approximately 150 square miles are within the urbanized area of the unincorporated County. The confluence of the Salt and Gila rivers, which drain most of eastern Arizona, is located in western Maricopa County. The Verde River, which drains much of north-central Arizona, joins the Salt River just east of the Phoenix metropolitan area. The Salt and Gila rivers are effluent-dominated streams west of Phoenix and are generally dry in the Phoenix metropolitan area due to the presence of upstream impoundments. The County’s municipal separate storm sewer system (MS4) is comprised mainly of County owned streets and flood control conveyance systems.
In December 2007, Maricopa County applied for and obtained coverage under permit AZG2002-002. The County’s Stormwater Quality Program will address urban runoff to reduce and potentially eliminate pollution from entering our main water bodies (Salt and Gila River Systems). Elements of the program include a Stormwater Management Plan (SWMP) that incorporates Best Management Practices (BMPs) associated with six (6) Minimum Control Measures as outlined by the federal rule. Some of the BMPs include: