On December 5, 2002, Arizona became one of 45 states authorized by the EPA to operate the NPDES Permit Program (Clean Water Act, sect 402) at the state level under the Arizona Pollutant Discharge Elimination System (AZPDES) Permit Program. All activities that discharge pollutants from any point source into waters of the United States (WOTUS) or non-WOTUS protected surface waters are required to obtain or seek coverage under an AZPDES permit. Pollutants can enter WOTUS or non_WOTUS protected surface waters via a variety of pathways, including agricultural, domestic, and industrial sources. For regulatory purposes, these sources are generally categorized as either point source or nonpoint source.
Arizona is authorized to issue Notices of Intent (NOIs) for construction and industrial activities under AZPDES. An AZPDES permit is required for any point source discharge of pollutants to a water of the United States. Because stormwater runoff can transport pollutants to either a municipal separate storm sewer system or to a WOTUS or non-WOTUS protected surface water, permits are required for those discharges. Most stormwater discharges are permitted under one of more general permits. However, an individual permit is required when the general permit requirements do not accurately represent the activity at a facility, so a permit is custom tailored to the site. An individual permit may be necessary if the Limitations of Coverage section of a general permit does not allow the facility's discharge to be covered by the general permit. It is the responsibility of every applicant to determine if any of the Limitations of Coverage apply to the facility seeking a general permit.
ADEQ AZPDES Why have an MS4 General Permit?