NPDES Permits in EPA’s Pacific Southwest (Region 9)
EPA's Pacific Southwest (Region 9) issues National Pollutant Discharge Elimination System (NPDES) permits for wastewater, industrial, and stormwater discharges on Tribal lands in Arizona, California, Nevada, and Navajo Nation Lands; for discharges in the U.S. Pacific Island territories of Guam, American Samoa, and the Commonwealth of the Northern Mariana Islands; and any discharges into federal ocean waters.
EPA’s Pretreatment Program regulates discharges of nondomestic wastewater to publicly owned treatment works (POTWs), in order to prevent discharge of pollutants that could interfere with POTW operations or pass through into receiving waters.
Municipalities subject to the stormwater regulations are evaluated to determine compliance with MS4 permits. See Region 9's MS4 Program Audit Reports.
Residual Designation Authority
Learn more about the 2024 final designation of stormwater discharges from certain commercial, industrial and institutional facilities in two Los Angeles watersheds.
Who Issues NPDES Permits in EPA's Pacific Southwest?
Arizona, California, Hawai'i, and Nevada issue NPDES permits for discharges on lands (other than Tribal lands) within those states. State-issued permits and related information are accessible through state program websites. See table below.
State | EPA-Issued Permits | State-Issued Permits |
---|---|---|
Arizona |
|
|
Navajo Nation |
|
N/A |
California |
|
|
Hawai'i | ||
Nevada | ||
American Samoa |
|
|
Guam |
|
|
Commonwealth of the Northern Mariana Islands (CNMI) |
|
|
Wake Island | N/A |

Arizona, California, Hawaii, Nevada, Pacific Islands, 148 Tribes
Public Notice
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Proposed Issuance of NPDES Permit for Vessel Testing a Pilot OceanWell off the Coast of California in Federal Waters and CWA §401 Water Quality Certification
EPA Region 9 is issuing notice of proposed action under the Clean Water Act (CWA) to issue a NPDES permit for the Vessel Testing a Pilot OceanWell located off the coast of California in federal waters under NPDES Permit No. CA0000018.
- Comments Due Date:
- Geographic Locations: Southwest, California
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Proposed Reissuance of NPDES General Permit for Bulk Fuel Facilities in Guam under NPDES Permit No. GUG000001
EPA Region 9 is issuing notice of a proposed action under the Clean Water Act (CWA) to reissue a National Pollutant Discharge Elimination System (NPDES) General Permit for Bulk Fuel Facilities in Guam under NPDES permit no. GUG000001.
- Comments Due Date:
- Geographic Locations: Southwest, Guam
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Mobil Saipan Terminal, Puerto Rico Village, MP; Proposed Reissuance of NPDES Permit No. MP0020397
EPA Region 9 is issuing notice of a proposed action to reissue a NPDES permit for the Mobil Saipan Terminal in the Commonwealth of the Northern Mariana Islands (CNMI) under NPDES Permit No. MP0020397.
- Comments Due Date:
- Geographic Locations: Southwest, Northern Mariana Islands
EPA Pacific Southwest Resources
- Arizona Tribal Lands (excluding Navajo Nation)
- Navajo Nation Lands
(AZ, NM, UT) - California Non-Tribal
- California Tribal Lands
- Hawai'i
- Nevada
- Pacific Island Territories
- Stormwater Program
- Pretreatment Program