Re-Issued Small MS4 Stormwater General Permit Impacts Existing and New Permittees

October 18, 2016 By Barbara U. Rodriguez-Pashkowski In Legal Alerts

On September 29, 2016, the Arizona Department of Environmental Quality (the “ADEQ”) re-issued the Small MS4 Stormwater General Permit, AZG2016-002 (the “Permit”) to provide coverage to existing and new MS4s for the discharge of stormwater to waters of the U.S. within Arizona.

Key updates include:

  • Existing permittees must update their Stormwater Management Program within six months of the Permit’s effective date; and, new permittees have one year from the effective date to establish a Stormwater Management Program.
  • All permittees must have enforcement authority. This may require a permittee to implement and/or amend its current codes and ordinances, and establish an enforcement response plan.
  • Existing and new permittees are automatically covered under the Permit for up to 180 days from September 30, 2016. To maintain coverage the permittee must complete and submit a Notice of Intent (“NOI”) within 180 days of September 30, 2016. A NOI is subject to public comment.
  • Existing permittees have 12 months to update their storm sewer system map showing the locations of all outfalls and the names and locations of all waters of the U.S. that receive discharges from those outfalls. New permittees must include a mapping schedule with their NOI and must complete their mapping by the end of year four of the Permit term.
  • Existing permittees will be billed in accordance with their current annual billing cycle. New permittees must submit the appropriate fee with their NOI. (See A.A.C R18-14-109).

The Permit, also known as the Arizona Pollutant Discharge Elimination System General Permit for Stormwater Discharges from Small Municipal Separate Storm Sewer Systems to Waters of the United States, went into effect on September 30, 2016, and is set to expire at midnight on September 29, 2021.

Existing Arizona MS4s include:

  • Apache Junction, Avondale, Arizona State University, Camp Verde, Chandler, Coconino County, Cottonwood, Davis Monthan AFB, Douglas, El Mirage, Flagstaff, Fountain Hills, Gilbert, Goodyear, Guadalupe, Lake Havasu, Litchfield Park, Luke AFB, Marana, Maricopa County, Marine Corps Air Stn, Nogales, Northern Arizona State University, Oro Valley, Paradise Valley, Peoria, Pinal County, Prescott, Prescott Valley, Sedona, Sierra Vista, South Tucson, Surprise, Tolleson, University of Arizona, Veterans Hospital in Phoenix, Veterans Hospital in Tucson, Yavapai County, Youngtown, Yuma, and Yuma County.

New MS4s (Based on 2010 Census) include:

  • Buckeye, Carefree, Casa Grande, Cave Creek, Queen Creek, Cochise County, and Mohave County.

Other MS4s:

  • Additional MS4s may be subject to coverage under this permit based on a more recent census, as determined by the U.S. Census Bureau, or be designated a regulated MS4 by the director of ADEQ pursuant to A.A.C. R18-9-A902(D).

For a full discussion of the Permit and to view the Permit, ADEQ’s fact sheet and other key documents visit

For more information, please contact
Barbara U. Rodriguez-Pashkowski at or 602-257-7494.

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