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Industrial stormwater facility

McMahon Steel Co Inc

9 37I023784 · Notice of Intent · Chula Vista, San Diego

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

Official

Facility record

Facility name
McMahon Steel Co Inc
WDID
9 37I023784
Application type
Notice of Intent
City
Chula Vista
County
San Diego
ZIP
91911
Primary SIC code
3441
SIC description
Fabricated Structural Metal
Date active
2012-08-14
Regional Water Board
Regional Board 9 - San Diego Region

Hydrologic

Geographic context

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

Official facility point
32.59458, -117.01550
HUC12 subwatershed
Poggi Canyon-Otay River
HUC12 code
180703041004
Impaired-water associations (derived)
2
Loading map…

303(d) context

Associated impaired waters

Grouped by derived geographic association class.

Derived

Nearby impaired water

1 waterbodies
Otay River

River & Stream · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (12) Benthic Community Effects, Bifenthrin, Copper, Cyfluthrin, Indicator Bacteria, Nitrogen +6 more

Distance 0.34 km

Confidence medium

Fact sheet

Same impaired-water subwatershed

1 waterbodies
Poggi Canyon Creek

River & Stream · Integrated Report category 5 · TMDL required

Listed pollutants / stressors (2) Nitrogen, Toxicity

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

Water Board-stated TMDL waste load allocations applied to this industrial permit in SMARTS.

Official record — SMARTS TMDL dataset, State Water Board

No SMARTS TMDL requirement is recorded for this WDID. In the statewide TMDL export only permits in Regions 4, 8 and 9 currently carry industrial TMDL requirements, so an absence here is not a statement that the facility discharges to an unimpaired water.

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
145
Sample events
20
Distinct parameters
8
Reporting years
2015 – 2017
First sample
2015-10-05
Latest sample
2018-03-15
Source regional dataset
Region 9 - San Diego
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 145
Sample dateLocationParameterResultUnitsEvent
2018-03-15DP #2AluminumND (non-detect / est.)mg/LQualifying Storm Event
2018-03-15DP #2Electrical Conductivity273umhos/cmQualifying Storm Event
2018-03-15DP #2Iron1.35mg/LQualifying Storm Event
2018-03-15DP #2Nitrate/Nitrite (Nitrite + Nitrate as N).55mg/LQualifying Storm Event
2018-03-15DP #2Oil and GreaseDNQ 2.1(non-detect / est.)mg/LQualifying Storm Event
2018-03-15DP #2pH6.7SUQualifying Storm Event
2018-03-15DP #2Total Suspended Solids (TSS)76mg/LQualifying Storm Event
2018-03-15DP #2ZincND (non-detect / est.)mg/LQualifying Storm Event
2018-02-27DP #2AluminumDNQ .8(non-detect / est.)mg/LQualifying Storm Event
2018-02-27DP #2Electrical Conductivity68.4umhos/cmQualifying Storm Event
2018-02-27DP #2Iron.742mg/LQualifying Storm Event
2018-02-27DP #2Nitrate/Nitrite (Nitrite + Nitrate as N)ND (non-detect / est.)mg/LQualifying Storm Event
2018-02-27DP #2Oil and GreaseDNQ 1.6(non-detect / est.)mg/LQualifying Storm Event
2018-02-27DP #2pH7.66SUQualifying Storm Event
2018-02-27DP #2Total Suspended Solids (TSS)DNQ 6(non-detect / est.)mg/LQualifying Storm Event
2018-02-27DP #2Zinc.077mg/LQualifying Storm Event
2017-01-19DP #2AluminumDNQ .35(non-detect / est.)mg/LQualifying Storm Event
2017-01-19DP #2Electrical Conductivity39.1umhos/cmQualifying Storm Event
2017-01-19DP #2Iron.446mg/LQualifying Storm Event
2017-01-19DP #2Nitrate/Nitrite (Nitrite + Nitrate as N).08mg/LQualifying Storm Event
2017-01-19DP #2Oil and GreaseND (non-detect / est.)mg/LQualifying Storm Event
2017-01-19DP #2pH7.43SUQualifying Storm Event
2017-01-19DP #2Total Suspended Solids (TSS)ND (non-detect / est.)mg/LQualifying Storm Event
2017-01-19DP #2Zinc.224mg/LQualifying Storm Event
2017-01-09DP #2Aluminum.17mg/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
3
Years with an NAL exceedance
2
Most recent evaluated year
RY 2017
Ruleset
igp_nal_ruleset_v1 / igp_nal_v1
ParameterNAL typeCalculated valueNALResultSamples usedMethod

Aluminum, Total

aluminum_total

Annual0 mg/L0.75 mg/LAt or below NALAnnual average of 1 eligible result(s) compared with the annual NAL.0× threshold1 eligible1 excluded1 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)

Iron, Total

iron_total

Annual1.046 mg/L1 mg/LAbove NALAnnual average of 2 eligible result(s) compared with the annual NAL.1.05× threshold2 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)

Nitrite Plus Nitrate (as N)

nitrate_nitrite_n

Annual0.55 mg/L as N0.68 mg/L as NAt or below NALAnnual average of 1 eligible result(s) compared with the annual NAL.0.81× threshold1 eligible1 excludedarithmetic 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.2 eligible2 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.2 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.2 eligible1 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

Annual0.077 mg/L0.26 mg/LAt or below NALAnnual average of 1 eligible result(s) compared with the annual NAL.0.3× threshold1 eligible1 excludedarithmetic 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

ZincMonitoringAbove NAL303(d) impairmentOtay River

1 reporting year above the annual NAL, most recently RY 2016 · 1 303(d) listing · association: derived receiving water (medium 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
9 37I023784
Source feature ID
17586
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