Clean Water Act discharge permit · NPDES TX0020478

IMPERIAL VALLEY WWTP, Houston, TX: NPDES TX0020478 discharge permit, effluent exceedances, inspections, penalties

EffectivePermit status
MajorDischarger class
50Pollutants under a numeric limit
5Pollutants with an effluent exceedance
1Inspections on file
0Formal enforcement actions

IMPERIAL VALLEY WWTP, held by CITY OF HOUSTON, holds NPDES permit TX0020478, which discharges to Hcfcdd P144-00-00, Hcfcdd P100-00-0. EPA’s file records it issued March 26, 2018 and expiring December 1, 2022.

IMPERIAL VALLEY WWTP, Houston, Texas: Individual permit TX0020478, held by CITY OF HOUSTON; Publicly owned treatment works; Effective; issued March 26, 2018, term to December 1, 2022; discharges to HCFCDD P144-00-00, HCFCDD P100-00-0.

Nitrogen, ammonia total [as N]: 3 limits, 12 violations of any kind, 12 effluent exceedances, latest July 31, 2026, largest 233% over the limit.
BOD, carbonaceous [5 day, 20 C]: 3 limits, 9 violations of any kind, 9 effluent exceedances, latest July 31, 2024, largest 99,999% over the limit.
E. coli: 6 limits, 6 violations of any kind, 4 effluent exceedances, latest September 30, 2025, largest 99,999% over the limit.
Flow, in conduit or thru treatment plant: 4 limits, 2 violations of any kind, 2 effluent exceedances, latest September 30, 2020, largest 19% over the limit.
Solids, total suspended: 3 limits, 2 violations of any kind, 2 effluent exceedances, latest July 31, 2024, largest 163% over the limit.
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Pimephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
NOEC Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
NOEC Lethal Static Renewal 7 Day Chronic Pimephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
NOEC Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
NOEC Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pinephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
LOEC Lethal Survival Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
LOEC Lethal Survival Static Renewal 7 Day Chronic Pimephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Ceriodaphnia dubia: 0 limits, 2 violations of any kind, 0 effluent exceedances.
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Pimephales promelas: 0 limits, 2 violations of any kind, 0 effluent exceedances.
Whole effluent toxicity - retest #1: 7 limits, 0 violations of any kind, 0 effluent exceedances.
Whole effluent toxicity - retest #2: 7 limits, 0 violations of any kind, 0 effluent exceedances.
Arsenic, dry weight: 5 limits, 0 violations of any kind, 0 effluent exceedances.
Chromium, sludge, total, dry weight [as Cr]: 5 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Low Flow Pass/Fail Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Low Flow Pass/Fail Lethal Static Renewal 7 Day Chronic Pimephales promelas: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Low Flow Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Low Flow Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Lethal Static Renewal 7 Day Chronic Pimephales promelas: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia: 4 limits, 0 violations of any kind, 0 effluent exceedances.
IC25 Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas: 4 limits, 0 violations of any kind, 0 effluent exceedances.
pH: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Selenium, dry weight: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Copper, dry weight: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Cadmium, dry weight: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Molybdenum, sludge, total, dry weight [as Mo]: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Zinc, sludge, total, dry weight [as Zn]: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Lead, sludge, total, dry weight [as Pb]: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Nickel, sludge, total, dry weight [as Ni]: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Mercury, sludge, total, dry weight [as Hg]: 3 limits, 0 violations of any kind, 0 effluent exceedances.
Nickel, total [as Ni]: 2 limits, 0 violations of any kind, 0 effluent exceedances.
Chlorine, total residual: 2 limits, 0 violations of any kind, 0 effluent exceedances.
Level of pathogen requirements achieved: 2 limits, 0 violations of any kind, 0 effluent exceedances.
Description of pathogen option used: 2 limits, 0 violations of any kind, 0 effluent exceedances.
Vector attraction reduction alternative used: 2 limits, 0 violations of any kind, 0 effluent exceedances.
Oxygen, dissolved [DO]: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Fecal coliform: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Polychlorinated biphenyls [PCBs]: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Toxicity characteristic leaching procedure: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual whole sludge application rate: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Ann. amt sludge disposed by other method: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual amt of sludge incinerated: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual sludge production, total: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual amount of sludge land applied: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual amt. sludge disposed surface unit: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual amt sludge disposed in landfill: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Annual amt sludge transported interstate: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Unit w/liner/leachate collection system: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Compliance w/part 258 sludge requirement: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Boundary areas: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Salmonella: 1 limit, 0 violations of any kind, 0 effluent exceedances.
Pollutant table from 503.13: 1 limit, 0 violations of any kind, 0 effluent exceedances.

January 23, 2026: Permit Violations - Violation Specified in Comment (ST6).
January 23, 2026: Evaluation (S).
November 8, 2024: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
July 15, 2024: Wet-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
May 11, 2024: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
January 12, 2024: Permit Violations - Violation Specified in Comment (ST6).
November 5, 2023: Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
December 12, 2022: Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
November 12, 2022: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
April 6, 2022: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
March 22, 2022: Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
August 25, 2021: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
June 18, 2021: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
May 20, 2021: Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
May 18, 2021: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
December 27, 2020: Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
December 1, 2020: Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment (EP6).
January 17, 2020: Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment (EP6).
January 16, 2020: WW SSO - Discharge to Waters (EP6).
September 6, 2019: WW SSO - Overflow to Dry Land or Building Backup (EP6).
March 14, 2018: Permit Violations - Violation Specified in Comment (ST6).
February 14, 2018: WW SSO - Discharge to Waters (EP6).

Texas holds 1,720 Publicly owned treatment works coverages of this permit type in EPA’s file; 726 were issued before TX0020478. CITY OF HOUSTON holds 13 permits in Texas.

Other permits held by CITY OF HOUSTON

HARRIS COUNTY WCID 76 WWTP, Houston: TX0025291, issued February 13, 2018
EASTHAVEN WWTP, Houston: TX0034886, issued November 2, 2017
INTERCONTINENTAL AIRPORT WWTP, Houston: TX0034916, issued January 30, 2018
SOUTHWEST WWTP, Houston: TX0062995, issued January 24, 2018
NORTHEAST WWTP, Houston: TX0063037, issued July 31, 2018
HARRIS COUNTY WCID 47 WWTP, Houston: TX0063045, issued October 17, 2017
CHOCOLATE BAYOU WWTP, Houston: TX0063061, issued December 21, 2017
BELTWAY WWTP, Houston: TX0065307, issued December 21, 2017
TIDWELL TIMBERS WWTP, Houston: TX0101460, issued February 13, 2018
WILLOWBROOK WWTP, Houston: TX0113131, issued December 27, 2017

Coverages issued nearest TX0020478

March 21, 2018: HARRIS COUNTY MUD 150 WWTP, Houston, TX0072893, held by HARRIS COUNTY MUD 150
March 21, 2018: HARRIS COUNTY MUD 104 WWTP, Houston, TX0074632, held by HARRIS COUNTY MUD 104
March 21, 2018: HARRIS COUNTY MUD 286 WWTF, Houston, TX0096920, held by HARRIS COUNTY MUD 286
March 21, 2018: HARRIS COUNTY MUD 360 WWTP, Houston, TX0113107, held by HARRIS COUNTY MUD NO. 360
March 21, 2018: HARRIS COUNTY MUD 24 WTP 2, Houston, TX0113115, held by HARRIS COUNTY MUD NO. 124
March 26, 2018: PONDEROSA JOINT POWERS AGENCY REGIONAL WWTP, Houston, TX0046761, held by PONDEROSA JOINT POWERS AGENCY
March 26, 2018: NORTHWEST HARRIS COUNTY MUD 5 WWP 1, Houston, TX0072346, held by NORTHWEST HARRIS COUNTY MUD 5
March 26, 2018: NW HARRIS COUNTY MUD 20 WWTP, Houston, TX0081337, held by NORTHWEST HARRISCOUNTY MUD 20
March 26, 2018: RICHEY ROAD MUD WWTP, Westfield, TX0092967, held by RICHEY ROAD MUD
March 26, 2018: HARRIS COUNTY MUD 344 WWTP, Houston, TX0104965, held by HARRIS COUNTY MUD 344

IMPERIAL VALLEY WWTP among its neighbors

EPA’s permit file holds 249 discharge permits in the Halls Bayou subwatershed (HUC 120401040604), TX0020478 among them. Its county holds 4,455, 195 of them major permits; TX0020478 is a major permit.

Other permits in the Halls Bayou subwatershed (HUC 120401040604)

11600 E HARDY ROAD, Houston: TXR05FH40, minor permit, permit term to August 13, 2026
48FORTY SOLUTIONS, Houston: TXR05GR07, minor permit, permit term to August 13, 2026
48FORTY SOLUTIONS, Houston: TXR05GX51, minor permit, permit term to August 13, 2026
8720 HIRSCH ROAD, Houston: TXR1539QA, minor permit, discharging to HUNTING BAYOU, permit term to March 4, 2028
A ALVAREZ RECYCLING LLC DBA NICHOLES SCRAP METAL, Houston: TXR05GS75, minor permit, permit term to August 13, 2026
A-PLAZA AUTO PARTS, Houston: TXR05GX88, minor permit, permit term to August 13, 2026
ACCURATE PRECISION PLATING, Houston: TXRNEX909, minor permit, permit term to August 13, 2026
ACTION AUTO PARTS & USED CARS, Houston: TXR05FU21, minor permit, permit term to August 13, 2026
AFS GROUP, Houston: TX0122521, minor permit, discharging to HCFCD DITCH;HALLS BAYOU;GREENS BAYOU TIDAL, permit term to February 4, 2024
AL STAR RECYCLING, Houston: TXR05Q552, minor permit, permit term to August 13, 2026

Identity

Facility as filed	IMPERIAL VALLEY WWTP
Permittee as filed	CITY OF HOUSTON
NPDES ID	TX0020478
Permit status	Effective
Permit type	Individual permit
Discharger class	Major discharger
Facility type	Publicly owned treatment works
Program	Publicly owned treatment works
Issued	March 26, 2018
Expiration date	December 1, 2022
Address	Houston, TX 77072
Receiving water	HCFCDD P144-00-00, HCFCDD P100-00-0
Subwatershed	Halls Bayou (HUC 120401040604)
Program components on file	POTW, Pretreatment
SIC	4952 – Sewerage Systems

Effluent limits and exceedances

62Pollutants on file
50Under a numeric limit
17With a violation of any kind
5With an effluent exceedance

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; the 60 with the most exceedances of 62 are shown.

Pollutant or measure	Limits	Violations, any kind	Effluent exceedances	Latest exceedance	Largest exceedance, as filed
Nitrogen, ammonia total [as N]	3	12	12	July 31, 2026	233% over the limit
BOD, carbonaceous [5 day, 20 C]	3	9	9	July 31, 2024	99,999% over the limit
E. coli	6	6	4	September 30, 2025	99,999% over the limit
Flow, in conduit or thru treatment plant	4	2	2	September 30, 2020	19% over the limit
Solids, total suspended	3	2	2	July 31, 2024	163% over the limit
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
Low Flow Pass/Fail Survival Test Static Renewal 7 Day Chronic Pimephales promelas	0	2	0
NOEC Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
NOEC Lethal Static Renewal 7 Day Chronic Pimephales promelas	0	2	0
NOEC Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
NOEC Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas	0	2	0
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pinephales promelas	0	2	0
LOEC Lethal Survival Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
LOEC Lethal Survival Static Renewal 7 Day Chronic Pimephales promelas	0	2	0
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Ceriodaphnia dubia	0	2	0
LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Pimephales promelas	0	2	0
Whole effluent toxicity - retest #1	7	0	0
Whole effluent toxicity - retest #2	7	0	0
Arsenic, dry weight	5	0	0
Chromium, sludge, total, dry weight [as Cr]	5	0	0
IC25 Low Flow Pass/Fail Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	4	0	0
IC25 Low Flow Pass/Fail Lethal Static Renewal 7 Day Chronic Pimephales promelas	4	0	0
IC25 Low Flow Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	4	0	0
IC25 Low Flow Pass/Fail Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas	4	0	0
IC25 Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	4	0	0
IC25 Lethal Static Renewal 7 Day Chronic Pimephales promelas	4	0	0
IC25 Sub-Lethal Static Renewal 7 Day Chronic Ceriodaphnia dubia	4	0	0
IC25 Sub-Lethal Static Renewal 7 Day Chronic Pimephales promelas	4	0	0
pH	3	0	0
Selenium, dry weight	3	0	0
Copper, dry weight	3	0	0
Cadmium, dry weight	3	0	0
Molybdenum, sludge, total, dry weight [as Mo]	3	0	0
Zinc, sludge, total, dry weight [as Zn]	3	0	0
Lead, sludge, total, dry weight [as Pb]	3	0	0
Nickel, sludge, total, dry weight [as Ni]	3	0	0
Mercury, sludge, total, dry weight [as Hg]	3	0	0
Nickel, total [as Ni]	2	0	0
Chlorine, total residual	2	0	0
Level of pathogen requirements achieved	2	0	0
Description of pathogen option used	2	0	0
Vector attraction reduction alternative used	2	0	0
Oxygen, dissolved [DO]	1	0	0
Fecal coliform	1	0	0
Polychlorinated biphenyls [PCBs]	1	0	0
Toxicity characteristic leaching procedure	1	0	0
Annual whole sludge application rate	1	0	0
Ann. amt sludge disposed by other method	1	0	0
Annual amt of sludge incinerated	1	0	0
Annual sludge production, total	1	0	0
Annual amount of sludge land applied	1	0	0
Annual amt. sludge disposed surface unit	1	0	0
Annual amt sludge disposed in landfill	1	0	0
Annual amt sludge transported interstate	1	0	0
Unit w/liner/leachate collection system	1	0	0
Compliance w/part 258 sludge requirement	1	0	0
Boundary areas	1	0	0
Salmonella	1	0	0
Pollutant table from 503.13	1	0	0

Inspections, violations and enforcement

21Single-event violations

Date	What EPA recorded	Agency
January 23, 2026	Permit Violations - Violation Specified in Comment	ST6
November 8, 2024	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
July 15, 2024	Wet-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
May 11, 2024	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
January 12, 2024	Permit Violations - Violation Specified in Comment	ST6
November 5, 2023	Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment	EP6
December 12, 2022	Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment	EP6
November 12, 2022	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
April 6, 2022	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
March 22, 2022	Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment	EP6
August 25, 2021	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
June 18, 2021	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
May 20, 2021	Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment	EP6
May 18, 2021	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
December 27, 2020	Dry-weather SSO discharge to waters of the U.S., not permit compliant, no endangerment	EP6
December 1, 2020	Dry-weather SSO, no discharge to waters of the U.S., not permit compliant, no endangerment	EP6
January 17, 2020	Dry-weather SSO, no discharge to waters of the U.S., that may endanger health or the environment	EP6
January 16, 2020	WW SSO - Discharge to Waters	EP6
September 6, 2019	WW SSO - Overflow to Dry Land or Building Backup	EP6
March 14, 2018	Permit Violations - Violation Specified in Comment	ST6
February 14, 2018	WW SSO - Discharge to Waters	EP6

Inspections

Date	What EPA recorded	Agency
January 23, 2026	Evaluation	S

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 TX0020478.

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

This public-records page covers Clean Water Act discharge permit NPDES TX0020478 for the IMPERIAL VALLEY WWTP in Houston, TX, held by CITY OF HOUSTON, with a status of Effective and a Major Discharger class. The page lists 5 pollutants under a numeric limit and 5 pollutants with an effluent exceedance, out of 62 pollutants on file.