ADEQ: Arizona Department of Environmental Quality, Arizona's Official Web Site
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Water Quality Division: Permits: Municipal Separate Storm Sewer System (MS4)

Public Comment Period for Draft 2015 Small MS4 General Permit

ADEQ has prepared a draft 2015 Small Municipal Separate Storm Sewer System General Permit (Small MS4 GP) that is intended to succeed the 2002 Small MS4 GP (Permit No. AZG2002-002) which is currently administratively continued. ADEQ welcomes comments on the draft 2015 permit and the Fact Sheet that goes with it. The 2015 documents can be accessed via the following links:

  • Draft 2015 Small MS4 General Permit -- (PDF)
  • Fact Sheet for 2015 permit -- (PDF)

Printed copies may be requested by contacting the ADEQ Records Center, (602) 771-4380.

A Public Notice regarding the proposed 2015 permit was published in the Arizona Administrative Register (as required by A.A.C. R18-9-A907(B)) on July 17, 2015.

For development of a final 2015 Small MS4 GP, ADEQ will consider written comments submitted or postmarked by Monday, August 17, 2015. Comments may be submitted by email, fax, postal mail, or hand-delivery to:

Attn: Christopher Henninger
Arizona Department of Environmental Quality
Water Quality Division, Surface Water Section
1110 West Washington Street, 5415A-1
Phoenix, Arizona 85007
Fax: (602) 771-4528
Email: [email protected]

After the public comment period ends, ADEQ will prepare a final 2015 Small MS4 GP with Fact Sheet and Response to Comments. If you would like to receive email notifications about this permit, please sign in to the ADEQ Email Updates web page and subscribe to the Phase II MS4 General Permit topic under “WQD”.

Municipal Stormwater Program

Management of stormwater runoff from urbanized areas is very important for protecting surface waters and our natural resources from pollutants. Concentrated development in urbanized areas substantially increases impervious surfaces, such as city streets, driveways, parking lots, and sidewalks, where pollutants from human activities settle and remain until a storm event washes them into nearby storm drains. Storm water runoff is often transported through municipal separate storm sewer systems and ultimately discharged into local rivers and streams without treatment. Common pollutants in stormwater runoff include litter, oil, chemicals, toxic metals, bacteria, and excess nutrients, like nitrogen and phosphorous. Poorly managed urban stormwater can also drastically alter the natural flow and infiltration of water, scour stream banks and harm or eliminate aquatic organisms and ecosystems.

A municipal separate storm sewer system, or MS4, is a conveyance or system of conveyances (roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains, etc.) that is also:

  • owned or operated by a public entity (which can include cities, townships, counties, highway departments, universities, etc.) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage districts, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act that discharges to waters of the United States;
  • designed or used for collecting or conveying stormwater;
  • which is not a combined sewer; and
  • which is not part of a publicly owned treatment works.

In 1972, Congress amended the Federal Water Pollution Control Act (commonly referred to as the Clean Water Act (CWA)) to prohibit the discharge of any pollutant to waters of the United States from a point source unless the discharge is authorized by a permit issued pursuant to the National Pollutant Discharge Elimination System (NPDES). The NPDES program is a program designed to track point sources and require the implementation of control measures necessary to minimize or eliminate the discharge of pollutants to waters of the U.S.

In 1987, Congress amended the CWA, Section 402(p), to require implementation of the stormwater program in two phases address stormwater discharges. The first phase of the program, commonly referred to as ‘‘Phase I,’’ was promulgated on November 16, 1990 (55 FR 47990). Phase I requires NPDES permits for storm water discharge from priority sources including municipal separate storm sewer systems (‘‘MS4s’’) generally serving populations of 100,000 or more.

On August 7, 1995, EPA promulgated a final rule that required facilities to be regulated under Phase II to apply for a NPDES permit by August 7, 2001, unless the NPDES permitting authority designates them as requiring a permit by an earlier date.

As specified by the CWA, permits for discharges from Phase I and Phase II municipal storm sewers must require controls to reduce the discharge of pollutants to the maximum extent practicable (MEP), including management practices, control techniques and system, design and engineering methods, and such other provisions the permitting authority determines appropriate for the control of such pollutants. ADEQ was delegated authority from U.S. EPA to implement the stormwater program in Arizona (except on Indian Country) on December 5, 2002.

Phase I

The Phase I Regulations require discharges from large construction sites, certain industrial activities, and operators of "medium" or "large" MS4s (MS4s that serve a population of 100,000 or greater), to obtain a permit and implement a storm water management program as a means to control discharges from their jurisdictional areas. Under the permits, the MS4 owner/operator must implement a collective series of programs to reduce the discharge of pollutants from the given storm sewer system to the maximum extent practicable in a manner that protects the water quality of nearby streams, lakes, rivers and wetlands.

There are 8 operators in Arizona that require a Phase I permit including:

Phase II

The Phase II Regulations (64 FR 68722) require smaller operators to obtain a permit for their stormwater discharges. These additional regulations stemmed from national studies and local findings that showed runoff from smaller urban areas increasingly impaired stream ecology and the health of aquatic life. While many of the water courses in Arizona are ephemeral or intermittent, these national regulations still apply to Arizona. Regulated MS4 operators include:

  • Operators that are located wholly or partially in an urbanized area as defined by the 2000 US Census (see 40 CFR 122.32(a)(1)). Regulated operators include five counties, 20 cities and 7 non-traditional municipalities. These operators were required to submit a Notice of Intent and Stormwater Management Program to ADEQ by March 10, 2003.
  • Operators designated by ADEQ (see 40 CFR 122.32(a)(2)). These operators were required to submit their Notice of Intent and Stormwater Management Program to ADEQ by December 2003. Designated operators include Camp Verde, Cottonwood, Douglas, Fountain Hills, Lake Havasu, Nogales, Sedona and Sierra Vista.

Operators of small MS4s in Arizona are regulated under a general permit. In accordance with the Small MS4 General Permit, each MS4 is required to prepare and implement a Stormwater Management Program Plan (SWMP). The SWMP must reduce the discharge of pollutants to the “maximum extent practicable”, protect water quality, and satisfy the appropriate water quality requirements of the Clean Water Act. Small MS4s must design into their programs six minimum control measures including: Public Education and Outreach; Public Participation/Involvement; Illicit Discharge Detection and Elimination; Construction Site Runoff Control; and Post-Construction Runoff Control. For the permit and forms, please follow the links below:

The following is a list of Small MS4s in Arizona, as established by the 2010 Census:


The MS4 fee schedule summarized below (established in A.A.C. R18-14-102 and R18-14-109) became effective July 01, 2011. The correct fee amount must be submitted with the Notice of Intent (NOI) form for processing:

Individual PermitFee
AZPDES Individual permit for municipal separate storm sewer system – Maximum amount, based on rate of $122 per hour.$40,000
AZPDES Amendment to an individual permit$12,500
Annual fee Individual MS4 permit$10,000

General Permit (fee is based on the population of the permitted area)Initial FeeAnnual Fee
Less than or equal to 10,000$2,500$2,500
Greater than 10,000 but less than or equal to 100,000$5,000$5,000
Greater than 100,000$7,500$7,500
The fee for a non-traditional municipal separate storm sewer system, such as a hospital, college or military facility $5,000$5,000

Additional Information

For additional information about the MS4 permitting program, consult these links:

For additional information, please contact us.

To request permit information, please contact the ADEQ Records Center at (602) 771-4380.