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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

NPDES Wastewater & Stormwater Permits

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The 1987 Water Quality Act (WQA) added section 402 (p) to the Clean Water Act, requiring that EPA issue National Pollutant Discharge Elimination System (NPDES) permits for the following five categories of stormwater discharges:

  • discharges permitted prior to February 4, 1987
  • discharges associated with industrial activity
  • discharges from large Municipal Separate Storm Sewer Systems (MS4s) (systems serving a population of 250,000 or more)
  • discharges from medium MS4s (systems serving a population of 100,000 or more, but less than 250,000)
  • discharges judged by the permitting authority to be significant sources of pollutants or which contribute to a violation of a water quality standard

Program Audits

Program Audits are being conducted to determine compliance and status of MS4 permitting. See the MS4 Program Audit Reports.

Stormwater Program, Phase I

The five categories listed above are generally referred to as Phase I of the stormwater program. On November 16, 1990, as a first step in carrying out the requirements of the 1987 WQA, EPA promulgated final regulations (40 CFR 122.26) Exiting EPA (disclaimer) for stormwater discharges from MS4s serving a population over 100,000, and for storm water discharges associated with industrial activity (55 Fed. Reg. 47990). The Phase I industrial stormwater program requires permitting for construction sites which disturb five or more acres and for numerous types of industrial facilities which are identified in the regulations by standard industrial classification (SIC) code or narrative description.

Additional background information on the stormwater program and numerous guidance documents may be found at EPA's NPDES Stormwater Program site. Copies of stormwater program materials may also be obtained by from EPA's Office of Water Resource Center at (202) 566-1729.

Stormwater Program, Phase II

The stormwater program also includes a Phase II, which addresses discharges not covered by Phase I. U.S. EPA issued final Phase II regulations on December 8, 1999 (64 Fed. Reg. 68722). These regulations require stormwater permits by March 10, 2003 for numerous small MS4s, construction sites of one to five acres, and industrial facilities owned or operated by small MS4s which were previously exempted under the Intermodal Surface Transportation Efficiency Act.

No Exposure Exemption

The Phase II regulations also modified the Phase I regulations to provide an exemption from stormwater permitting for industrial facilities within the categories described at 40 CFR 122.26(b) (14) (i)-(ix) which have no exposure of industrial materials and activities to stormwater. Facilities claiming the exemption must submit a no exposure certification to the permitting authority once every five years (see also no exposure certification guidance). The Phase II regulations retain the no exposure exemption for "light" industrial facilities listed in the Phase I regulations at 40 CFR 122.26(b) (14) (xi). However, to claim the exemption, these facilities must now also submit the no exposure certification once every five years. Construction sites are ineligible for the no exposure exemption.

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Permitting Authority

The NPDES permit program, including stormwater permitting, has been delegated to the state in Arizona, California, Hawaii and Nevada (except for Indian lands in these states). EPA Region 9 is the permitting authority for Indian lands in Arizona, California and Nevada, and the Pacific Island Territories of Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, Johnston Atoll, and Wake and Midway Islands. The vast majority of construction sites and industrial facilities within EPA Region 9 (and nationally) which discharge stormwater are permitted under general NPDES permits.

Permits Issued by EPA Region 9

EPA Region 9 developed this summary of stormwater permits (PDF) (1 pg, 32K).

Construction: For the areas where Region 9 is the permitting authority, one general permit has been issued for construction sites disturbing one or more acres (73 FR 40338, July 14, 2008). This permit is a reissuance of the previous permit which was issued on July 1, 2003.

Industrial: A second general permit (called the multi-sector general permit (MSGP)) (73 FR 56572, September 29, 2008) has been issued for industrial facilities other than construction sites. The permit is a reissuance of the previous MSGP which was issued on October 30, 2000.

Construction and Industrial Permit Application: To apply for permit coverage under the construction general permit, a construction notice of intent (NOI) must be submitted to EPA. A similar industrial notice of intent is required for the MSGP. Permit coverage under the construction general permit may be terminated by submitting a construction notice of termination. Permit coverage under the MSGP may be terminated by submitting an industrial notice of termination.

Phase I MS4s for Arizona: Region 9 issued MS4 permits for the cities of Phoenix, Tempe, Mesa, Scottsdale, Glendale, Tucson, Pima County, and the Arizona Department of Transportation (ADOT) in 1997 prior to Arizona receiving authorization to administer the NPDES permit program. The MS4 permits for the city of Phoenix and ADOT were recently reissued by the Arizona Department of Environmental Quality, and the State is currently in the process of reissuing the other MS4 permits.

Phase II Small MS4s: Region 9 has issued individual permits for the small MS4s in the geographic areas under its jurisdiction: Agua Caliente Band of Cahuilla Indians and the Island of Saipan in the Commonwealth of the Northern Mariana Islands.

Permits Issued by States

MS4s for AZ, CA, HI and NV: MS4 permits have been issued in the States of California, Hawaii and Nevada for all the large and medium MS4s covered by the Phase I stormwater program. General NPDES permits have also been issued for Phase II small MS4s in the States of Arizona, California, Hawaii and Nevada.

Construction/Industrial Permits for AZ, CA, HI, and NV: General NPDES permits have been issued in California, Hawaii and Nevada for stormwater discharges from construction sites disturbing one or more acres, and for Phase I industrial facilities. In Nevada, the State has also issued a separate general permit covering metal mining facilities. The State of Arizona has issued a general permit for construction sites disturbing one or more acres. In addition, the State of Arizona is now administering EPA’s MSGP for non-Indian lands in Arizona; when the MSGP was issued in 2000 (prior to the State receiving NPDES program authorization) it covered the entire State of Arizona.

Contact Information

EPA Region 9 Stormwater Program
Eugene Bromley (bromley.eugene@epa.gov) (415) 972-3510

Or consult state stormwater contacts.

Petitions to Region 9, Pacific Southwest

September 2015 Petitions

On September 17, 2015, EPA Region 9 received another petition seeking designation of unregulated stormwater discharges from commercial, industrial and institutional sites in specific watersheds in Los Angeles County. The watersheds are the Alamitos Bay/Los Cerritos Channel watershed and the Dominguez Channel and Los Angeles/Long Beach Inner Harbor watersheds. Many of the receiving waters in these watersheds are currently impaired for certain pollutants such as heavy metals or other pollutants.

For these watersheds, the Region concluded that effective programs, stemming primarily from MS4 permits issued by the Los Angeles Regional Board, are already underway to address the existing water quality impairments. Accordingly, the Region again declined to begin the designation process for the discharges within these watersheds. The Region will continue to monitor progress in restoring and maintaining water quality in the watersheds and if circumstances change, may exercise its designation authority.

Additional information concerning state stormwater programs may be obtained from EPA and the following state agencies:

July 2013 Petition

On July 10, 2013, EPA Region 9 received a petition seeking designation for Clean Water Act permitting of currently unregulated stormwater discharges from commercial, industrial, and institutional sites that discharge non de minimis amounts of certain pollutants to waters that are impaired by those pollutants. The pollutants identified were lead, zinc, copper, phosphorus, nitrogen, sediment, biological oxygen demand, and chemical oxygen demand. The Regions conducted analyses in which each considered: 1) the likelihood for exposure of pollutants to precipitation for the category of sources identified, 2) whether sufficient data are available on which to make a determination of potential adverse water quality impacts for the category of sources identified, and 3) whether such sources were adequately addressed by other environmental programs.

Region 9 has concluded that there is insufficient data at this time on which to base a region-wide designation of commercial, industrial, and institutional sites and, given the scope of the petition, the Region does not have that level of information reasonably available. In Region 9, existing MS4 permits cover the majority of stormwater discharges from the areas where these sites are predominantly located. Although the Region has declined to begin a designation process for a categorical designation of stormwater discharges from these sites to impaired waters as requested by petitioners, an important part of the Region’s ongoing stormwater program is evaluating the contribution of unregulated stormwater discharges to water quality exceedances. The Region has previously exercised its authority to designate unregulated stormwater discharges for NPDES permitting and will continue to do so as information supports targeted designations.

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Regional Stormwater Information

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In California

Municipal Stormwater Programs

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In Arizona

In California

When Stormwater is Used to Recharge Ground Water

Discharges to ground water may be subject to local, state or federal requirements. Specifically, discharges via subsurface fluid distribution systems or other subsurface infiltrative devices may be subject to the federal underground injection control (UIC) requirements. The UIC program, authorized pursuant to the U.S. Safe Drinking Water Act, exists to prevent the endangerment of underground sources of drinking water. Stormwater injection wells need to be listed on state or federal inventory lists, and should not be used for the disposal of fluids other than storm water. To limit the potential for ground water contamination, EPA recommends that stormwater injection wells be constructed with spill catchment, and not be constructed to intersect the water table. For more information, see the list of EPA Regional UIC contacts.

Reasonable Assurance Analysis Workshop (September 23, 2015)

EPA Region IX and the San Francisco Bay Water Board hosted a workshop on September 23 intended to inform the San Francisco Bay Area stormwater permittees on Reasonable Assurance Analysis (RAA). RAA is a required component of the final Municipal Regional [MS4 Phase I] permit and linked to the requirement for all permittees to develop Green Infrastructure Plans. RAA is a useful tool to support stormwater planning for both MS4 Phase I and Phase II permits. RAA uses analytical models to evaluate stormwater problems and verify a particular suite of management practices will be sufficient to ensure water quality goals are met.

RAA efforts have already been performed in several California municipalities: including Los Angeles, San Diego, Paso Robles, and the Lake Tahoe Region, each of which were presented as case studies at the workshop. In the S.F. Bay Area, the San Francisco Estuary Institute's Green Plan-IT tool was also presented as a work in progress at the workshop.

The workshop provided explanations about RAA by EPA and Water Board representatives. It also included presentations on each case study with a pair of speakers –the municipality or county representative and the consultants who have developed the modeling tools in these different regions.

Click on the links below to view the powerpoint presentations for the various modules or watch YouTube videos of the presentations to hear what the speakers presented.

All links in this section exit EPA. Exiting EPA (disclaimer)
Presentation PDFs and YouTube Videos of Reasonable Assurance Analysis Workshop (September 23, 2015)
Webinar Presentation Materials Webinar

Workshop Agenda and Case Study Background Information (PDF) (10 pp, 94 K)

Introduction: Dave Smith (EPA Region 9) and Tom Mumley (SF Bay Water Board) (PDF) (25 pp, 3.3 MB)

(watch video)

Module 1: City Los Angeles (“Huub” Cox, City of LA and Steve Carter, Paradigm H2O) (PDF) (18 pp,2.5 MB)

(watch video)

Module 2: Paso Robles (Dave LaCaro, City of Paso Robles and Nicole Beck, 2NDNATURE) (PDF) (XX pp, XX K)

(watch video)

Module 3: City of San Diego (Drew Kleis, City of San Diego) (PDF) (16 pp, 3.2 MB)

(watch video)
(ends at 23:00)

Module 3b: LA Water Board (Renee Purdy) (PDF) (17 pp, 1.5 MB)

 (watch video)
(starts at 23:00) 

Module 4: Lake Tahoe (Peter Kraatz, Placer County and Chad Praul, Environ. Incentives) (PDF) (15 pp, 1.9 MBK)

(watch video)

Module 5: San Mateo County (Matt Fabry and Lester McKee, S.F. Estuary Institute) (PDF) (35 pp, 6 MB)

(watch video)

Synthesis and Next Steps: Keith Lichten (SF Bay Water Board) (no presentation available)



Reasonable Assurance Analysis Guide (February 2017)

Developing Reasonable Assurance: A Guide to Performing Model-Based Analysis to Support Municipal Stormwater Program Planning (PDF) (51 pp, 1.5 MB)

Appendices-Developing Reasonable Assurance: A Guide to Performing Model-Based Analysis to Support Municipal Stormwater Program Planning (PDF) (53 pp, 2.9 MB)


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