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Industrial stormwater facility

Thompson Gundrilling Inc

4 19I014804 · Notice of Intent · Van Nuys, Los Angeles

Official record — State Water Resources Control Board, Industrial General Permit

Official

Facility record

Facility name
Thompson Gundrilling Inc
WDID
4 19I014804
Application type
Notice of Intent
City
Van Nuys
County
Los Angeles
ZIP
91402
Primary SIC code
3399
SIC description
Primary Metal Products, NEC
Date active
1998-12-05
Regional Water Board
Regional Board 4 - Los Angeles Region

Hydrologic

Geographic context

Official facility coordinate plotted against the official 2026 impaired-water geometry.

Official facility point
34.20996, -118.43425
HUC12 subwatershed
Tujunga Wash-Los Angeles River
HUC12 code
180701050208
Impaired-water associations (derived)
6
Loading map…

303(d) context

Associated impaired waters

Grouped by derived geographic association class.

Derived

Subwatershed + nearby

1 waterbodies
Tujunga Wash (LA River to Hansen Dam)

River & Stream · Integrated Report category 4a · TMDL approved by USEPA

Listed pollutants / stressors (4) Ammonia, Copper, Indicator Bacteria, Trash

Distance 0.74 km

Confidence high

Fact sheet

Same impaired-water subwatershed

5 waterbodies
Balboa Lake

Lake & Reservoir · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (3) Oxygen, Dissolved, Temperature, water, Toxicity

Distance

Confidence low

Fact sheet

Los Angeles River Reach 4 (Sepulveda Dr. to Sepulveda Dam)

River & Stream · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (4) Indicator Bacteria, Nutrients (Algae), Toxicity, Trash

Distance

Confidence low

Fact sheet

Los Angeles River Reach 5 ( within Sepulveda Basin)

River & Stream · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (8) Benthic Community Effects, Copper, Lead, Nutrients (Algae), Oil, Selenium +2 more

Distance

Confidence low

Fact sheet

Los Angeles River Reach 6 (Above Sepulveda Flood Control Basin)

River & Stream · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (9) Chlordane, Chloride, Copper, Indicator Bacteria, Selenium, Sulfates +3 more

Distance

Confidence low

Fact sheet

Wildlife Lake

Lake & Reservoir · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (1) Oxygen, Dissolved

Distance

Confidence low

Fact sheet

Associations are calculated from official facility coordinates, USGS HUC12 boundaries, and official 2026 impaired-water geometry. They do not establish a discharge connection or causation.

TMDL requirements (3)

Numeric effluent limits and action levels stated by the Water Board for this permit, with the receiving water named in the TMDL.

Official record — SMARTS TMDL dataset, State Water Board
Stated requirements
3
TMDLs
1
Regulated parameters
3
Limit due dates
2020-07-01 – 2020-07-01
Includes interim limits
No
Source regional dataset
Region 4 - Los Angeles
Source retrieved
Aug 21, 2026

Official SMARTS public reports

Los Angeles River Metals TMDL

Receiving water named in TMDL Los Angeles River and Los Angeles River Tributaries

3 limits
ParameterLimit typePeriodBasisLimitDue dateReported results for parameter
Copper, TotalVocabulary match: Copper (narrower)NELFINALINSTANTANEOUS.06749 mg/L2020-07-0136 results · latest 2026-04-13
Lead, TotalVocabulary match: Lead (narrower)NELFINALINSTANTANEOUS.094 mg/L2020-07-0136 results · latest 2026-04-13
Zinc, TotalVocabulary match: Zinc (narrower)NELFINALINSTANTANEOUS.159 mg/L2020-07-0136 results · latest 2026-04-13
Derivedapplies only to the 303(d) waterbody link and the parameter vocabulary match.

Limit values, limit periods, parameters, TMDL names and receiving-water names are reproduced exactly as stated by the Water Board in SMARTS. California Stormwater Intelligence does not compare reported monitoring results to these limits and makes no exceedance, violation or compliance determination. Where a stated receiving-water name is linked to a 2026 303(d) waterbody, that link is a derived exact-name match, not a Water Board determination.

Official monitoring

SMARTS monitoring

Self-reported industrial stormwater sampling results as submitted by the discharger to SMARTS.

Official record — SMARTS parameter data, State Water Board
Reported results
310
Sample events
22
Distinct parameters
9
Reporting years
2015 – 2025
First sample
2016-01-05
Latest sample
2026-04-13
Source regional dataset
Region 4 - Los Angeles
Source retrieved
Aug 21, 2026

Official SMARTS public reports

Parameters reported

Reported results over time

Loading reported results…

Most recent reported results

Latest 25 of 310
Sample dateLocationParameterResultUnitsEvent
2026-04-13drain 1Aluminum.289mg/LQualifying Storm Event
2026-04-13drain 1Aluminum.289mg/LQualifying Storm Event
2026-04-13drain 1Copper.00737mg/LQualifying Storm Event
2026-04-13drain 1Copper.00737mg/LQualifying Storm Event
2026-04-13drain 1Iron.955mg/LQualifying Storm Event
2026-04-13drain 1Iron.955mg/LQualifying Storm Event
2026-04-13drain 1Lead.0018mg/LQualifying Storm Event
2026-04-13drain 1Lead.0018mg/LQualifying Storm Event
2026-04-13drain 1Oil and GreaseDNQ 2.2(non-detect / est.)mg/LQualifying Storm Event
2026-04-13drain 1Oil and GreaseDNQ 2.2(non-detect / est.)mg/LQualifying Storm Event
2026-04-13drain 1pH7SUQualifying Storm Event
2026-04-13drain 1pH7SUQualifying Storm Event
2026-04-13drain 1Total Suspended Solids (TSS)23.9mg/LQualifying Storm Event
2026-04-13drain 1Total Suspended Solids (TSS)23.9mg/LQualifying Storm Event
2026-04-13drain 1Zinc.505mg/LQualifying Storm Event
2026-04-13drain 1Zinc.505mg/LQualifying Storm Event
2025-11-20drain 1Aluminum.174mg/LQualifying Storm Event
2025-11-20drain 1Aluminum.174mg/LQualifying Storm Event
2025-11-20drain 1Copper.00947mg/LQualifying Storm Event
2025-11-20drain 1Copper.00947mg/LQualifying Storm Event
2025-11-20drain 1Iron.159mg/LQualifying Storm Event
2025-11-20drain 1Iron.159mg/LQualifying Storm Event
2025-11-20drain 1LeadDNQ .000879(non-detect / est.)mg/LQualifying Storm Event
2025-11-20drain 1LeadDNQ .000879(non-detect / est.)mg/LQualifying Storm Event
2025-11-20drain 1Oil and GreaseND (non-detect / est.)mg/LQualifying Storm Event

Monitoring rows are official self-reported SMARTS submissions, joined to this facility by WDID. California Stormwater Intelligence does not restate, correct, average or evaluate reported values, and no benchmark comparison or violation determination is made.

YDOS-derived

Numeric Action Level comparison

Reported SMARTS analytical results compared against the Numeric Action Levels of the Industrial General Permit version in effect for each reporting year (July 1 – June 30).

Derived
Reporting years evaluated
11
Years with an NAL exceedance
6
Most recent evaluated year
RY 2025
Ruleset
igp_nal_ruleset_v1 / igp_nal_v1
ParameterNAL typeCalculated valueNALResultSamples usedMethod

Aluminum, Total

aluminum_total

Annual0.255 mg/L0.75 mg/LAt or below NALAnnual average of 6 eligible result(s) compared with the annual NAL.0.34× threshold6 eligiblearithmetic mean of all eligible effluent results in the July 1 - June 30 reporting year (censored results assigned zero only where MDL and ML were both reported)

Copper, Total

copper_total

Annual0.038 mg/L0.033 mg/LAbove NALAnnual average of 6 eligible result(s) compared with the annual NAL.1.15× threshold6 eligiblearithmetic mean of all eligible effluent results in the July 1 - June 30 reporting year (censored results assigned zero only where MDL and ML were both reported)

Iron, Total

iron_total

Annual0.708 mg/L1 mg/LAt or below NALAnnual average of 6 eligible result(s) compared with the annual NAL.0.71× threshold6 eligiblearithmetic mean of all eligible effluent results in the July 1 - June 30 reporting year (censored results assigned zero only where MDL and ML were both reported)

Lead, Total

lead_total

Annual0.004 mg/L0.262 mg/LAt or below NALAnnual average of 6 eligible result(s) compared with the annual NAL.0.02× threshold6 eligible2 non-detect as zeroarithmetic mean of all eligible effluent results in the July 1 - June 30 reporting year (censored results assigned zero only where MDL and ML were both reported)

Oil and Grease

oil_grease

Instantaneous maximum0 samples above25 mg/LAt or below NALNo eligible result in this reporting year was outside the instantaneous maximum NAL.6 eligible6 non-detect as zerocount of eligible effluent results outside the instantaneous maximum NAL within the July 1 - June 30 reporting year

pH

ph

Instantaneous maximum0 samples above6 – 9 pH unitsWithin NAL rangeNo eligible result in this reporting year was outside the instantaneous maximum NAL.6 eligiblecount of eligible effluent results outside the instantaneous maximum NAL within the July 1 - June 30 reporting year

Total Suspended Solids (TSS)

tss

Instantaneous maximum0 samples above400 mg/LAt or below NALNo eligible result in this reporting year was outside the instantaneous maximum NAL.6 eligible2 non-detect as zerocount of eligible effluent results outside the instantaneous maximum NAL within the July 1 - June 30 reporting year

Zinc, Total

zinc_total

Annual0.486 mg/L0.26 mg/LAbove NALAnnual average of 6 eligible result(s) compared with the annual NAL.1.87× threshold6 eligiblearithmetic mean of all eligible effluent results in the July 1 - June 30 reporting year (censored results assigned zero only where MDL and ML were both reported)

YDOS-derived overlap

Pollutant overlap with impaired receiving waters

Parameters where this facility has an NAL exceedance in at least one reporting year and the geographically associated waterbody carries a 303(d) listing for the same pollutant.

Derived

CopperMonitoringAbove NAL303(d) impairmentLos Angeles River Reach 5 ( within Sepulveda Basin)

3 reporting years above the annual NAL, most recently RY 2025 · 1 303(d) listing · 1 stated TMDL requirement · association: derived watershed association (low confidence)

CopperMonitoringAbove NAL303(d) impairmentLos Angeles River Reach 6 (Above Sepulveda Flood Control Basin)

3 reporting years above the annual NAL, most recently RY 2025 · 1 303(d) listing · 1 stated TMDL requirement · association: derived watershed association (low confidence)

CopperMonitoringAbove NAL303(d) impairmentTujunga Wash (LA River to Hansen Dam)

3 reporting years above the annual NAL, most recently RY 2025 · 1 303(d) listing · 1 stated TMDL requirement · association: derived nearby in watershed (high confidence)

ZincMonitoringAbove NAL303(d) impairmentLos Angeles River Reach 6 (Above Sepulveda Flood Control Basin)

2 reporting years above the annual NAL, most recently RY 2025 · 1 303(d) listing · 1 stated TMDL requirement · association: derived watershed association (low confidence)

Overlap is informational co-occurrence between a derived NAL comparison and an official 303(d) listing. It is not evidence that this facility caused or contributed to the impairment.

An NAL exceedance is a permit-defined condition that triggers Exceedance Response Actions under the Industrial General Permit. It is not a violation, an enforcement action, or a Water Board compliance determination. Annual values use the arithmetic average of eligible results with non-detects treated as zero; instantaneous maximum NALs (total suspended solids, oil and grease, pH) are exceeded when two or more eligible results in a reporting year fall outside the level. Rules transcribed from 2014-0057-DWQ as amended by 2015-0122-DWQ (effective 2015-07-01, superseded 2020-06-30); 2014-0057-DWQ as amended by 2018-0028-DWQ (effective 2020-07-01).

Provenance

Source & provenance

Source agency
California State Water Resources Control Board
Source dataset
Industrial General Permit — permitted facilities (statewide GIS layer)
WDID
4 19I014804
Source feature ID
11711
Application type
Notice of Intent
Regional board derivation
WDID region prefix
Geometry status
valid
Last successful facility import
Aug 21, 2026, 1:57 AM UTC

Official IGP permitted facilities feature layer