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Clean Water Act discharge permit · NPDES AZ0023558

SRP - SANTAN GENERATING STATION, Gilbert, AZ: NPDES AZ0023558 discharge permit, effluent exceedances, inspections, penalties

SRP - SANTAN GENERATING STATION, held by Srp - Santan Generating Station, holds NPDES permit AZ0023558. EPA’s file records it issued August 13, 2024 and expiring August 12, 2029.

SRP - SANTAN GENERATING STATION, Gilbert, Arizona: Individual permit AZ0023558, held by Srp - Santan Generating Station; Effective; issued August 13, 2024, term to August 12, 2029.

  • pH: 6 limits, 14 violations of any kind, 10 effluent exceedances, latest December 31, 2013.
  • Solids, total suspended: 6 limits, 4 violations of any kind, 4 effluent exceedances, latest January 31, 2017, largest 53% over the limit.
  • Selenium, total recoverable: 6 limits, 74 violations of any kind, 3 effluent exceedances, latest December 31, 2016, largest 33% over the limit.
  • Chlorine, total residual: 6 limits, 3 violations of any kind, 3 effluent exceedances, latest February 28, 2015, largest 67% over the limit.
  • Copper, total recoverable: 4 limits, 73 violations of any kind, 2 effluent exceedances, latest February 28, 2015, largest 8% over the limit.
  • Chromium, hexavalent dissolved [as Cr]: 6 limits, 74 violations of any kind, 1 effluent exceedance, latest December 31, 2008, largest 41% over the limit.
  • Hardness, total [as CaCO3]: 6 limits, 24 violations of any kind, 0 effluent exceedances.
  • Oil & Grease: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Chromium, total [as Cr]: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Zinc, total recoverable: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Chromium, total recoverable: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Flow, in conduit or thru treatment plant: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Chlorine, free available: 6 limits, 0 violations of any kind, 0 effluent exceedances.
  • Cyanide, total [as CN]: 4 limits, 0 violations of any kind, 0 effluent exceedances.
  • Iron, total recoverable: 4 limits, 0 violations of any kind, 0 effluent exceedances.
  • Mercury, total recoverable: 4 limits, 0 violations of any kind, 0 effluent exceedances.
  • Arsenic, total recoverable: 2 limits, 0 violations of any kind, 0 effluent exceedances.
  • Boron, total recoverable: 2 limits, 0 violations of any kind, 0 effluent exceedances.
  • Nickel, total recoverable: 2 limits, 0 violations of any kind, 0 effluent exceedances.
  • April 21, 2026: Evaluation (S).

SRP - SANTAN GENERATING STATION among its neighbors

Its county holds 618, 31 of them major permits; AZ0023558 is a major permit.

Other permits in the county

Identity

Facility as filedSRP - SANTAN GENERATING STATION
Permittee as filedSrp - Santan Generating Station
NPDES IDAZ0023558
Permit statusEffective
Permit typeIndividual permit
Discharger classMajor discharger
Facility typeNot a publicly owned treatment works
IssuedAugust 13, 2024
Expiration dateAugust 12, 2029
AddressGilbert, AZ 85296
SIC4911 – Electric Services
Other EPA IDs (FRS)RCRA handler AZD000629493; ICIS-AIR source AZMCA004013X003315

Effluent limits and exceedances

An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant.

Pollutant or measureLimitsViolations, any kindEffluent exceedancesLatest exceedanceLargest exceedance, as filed
pH61410December 31, 2013
Solids, total suspended644January 31, 201753% over the limit
Selenium, total recoverable6743December 31, 201633% over the limit
Chlorine, total residual633February 28, 201567% over the limit
Copper, total recoverable4732February 28, 20158% over the limit
Chromium, hexavalent dissolved [as Cr]6741December 31, 200841% over the limit
Hardness, total [as CaCO3]6240
Oil & Grease600
Chromium, total [as Cr]600
Zinc, total recoverable600
Chromium, total recoverable600
Flow, in conduit or thru treatment plant600
Chlorine, free available600
Cyanide, total [as CN]400
Iron, total recoverable400
Mercury, total recoverable400
Arsenic, total recoverable200
Boron, total recoverable200
Nickel, total recoverable200

Inspections, violations and enforcement

EPA’s single-event violation file, as loaded, holds no violation for NPDES AZ0023558.

Inspections

DateWhat EPA recordedAgency
April 21, 2026EvaluationS

Formal enforcement and penalties

0 formal actions, 0 of them with a penalty assessed. Federal and state penalties are separate figures from separate authorities and are shown as each was filed, never added together.

Informal enforcement

EPA’s informal enforcement file holds no action for NPDES AZ0023558.

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Nearby on the register

Figures from EPA’s ICIS-NPDES download, loaded October 14, 2026.

What this page shows

This public-records page covers NPDES permit AZ0023558, held by SRP - SANTAN GENERATING STATION in Gilbert, AZ, as a Major Discharger under an individual, effective permit issued August 13, 2024 and expiring August 12, 2029. The page lists 19 pollutants on file, 6 of which carry a numeric limit and 6 of which show an effluent exceedance.