Industrial stormwater facility
4 19I018897 · Notice of Intent · Walnut, Los Angeles
Official
Hydrologic
Official facility coordinate plotted against the official 2026 impaired-water geometry.
303(d) context
Grouped by derived geographic association class.
River & Stream · Integrated Report category 5 · TMDL required
Listed pollutants / stressors (5) Chlorine, Indicator Bacteria, pH, Total Dissolved Solids, Toxicity
River & Stream · Integrated Report category 4a · TMDL approved by USEPA
Listed pollutants / stressors (1) Indicator Bacteria
River & Stream · Integrated Report category 5 · TMDL required
Listed pollutants / stressors (1) Toxicity
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.
Water Board-stated TMDL waste load allocations applied to this industrial permit in SMARTS.
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
Self-reported industrial stormwater sampling results as submitted by the discharger to SMARTS.
Loading reported results…
| Sample date | Location | Parameter | Result | Units | Event |
|---|---|---|---|---|---|
| 2025-10-14 | SD#1 | Copper | .0267 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#1 | Oil and Grease | 4.6 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#1 | Total Dissolved Solids | 5 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#1 | Total Suspended Solids (TSS) | 72.4 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#1 | Zinc | .359 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#10 | Copper | .0242 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#10 | Oil and Grease | 4.2 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#10 | Total Dissolved Solids | 5 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#10 | Total Suspended Solids (TSS) | 27.1 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#10 | Zinc | .223 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#15 | Copper | .0643 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#15 | Oil and Grease | 10.2 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#15 | Total Dissolved Solids | 25 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#15 | Total Suspended Solids (TSS) | 257 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#15 | Zinc | .968 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#16 | Copper | .0341 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#16 | Oil and Grease | 11.7 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#16 | Total Dissolved Solids | 5 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#16 | Total Suspended Solids (TSS) | 110 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#16 | Zinc | .119 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#8 | Copper | .00913 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#8 | Oil and Grease | 6.1 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#8 | Total Dissolved Solids | 10 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#8 | Total Suspended Solids (TSS) | 20.5 | mg/L | Qualifying Storm Event |
| 2025-10-14 | SD#8 | Zinc | .221 | mg/L | Qualifying 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
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).
| Parameter | NAL type | Calculated value | NAL | Result | Samples used | Method |
|---|---|---|---|---|---|---|
Copper, Total copper_total | Annual | 0.028 mg/L | 0.033 mg/L | At or below NALAnnual average of 6 eligible result(s) compared with the annual NAL.0.85× threshold | 6 eligible | arithmetic 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 maximum | —0 samples above | 25 mg/L | At or below NALNo eligible result in this reporting year was outside the instantaneous maximum NAL. | 6 eligible | count of eligible effluent results outside the instantaneous maximum NAL within the July 1 - June 30 reporting year |
Total Suspended Solids (TSS) tss | Instantaneous maximum | —0 samples above | 400 mg/L | At or below NALNo eligible result in this reporting year was outside the instantaneous maximum NAL. | 6 eligible | count of eligible effluent results outside the instantaneous maximum NAL within the July 1 - June 30 reporting year |
Zinc, Total zinc_total | Annual | 0.367 mg/L | 0.26 mg/L | Above NALAnnual average of 6 eligible result(s) compared with the annual NAL.1.41× threshold | 6 eligible | arithmetic 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
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.
pHMonitoringAbove NAL303(d) impairmentSan Jose Creek Reach 1 (SG Confluence to Temple St.)
3 reporting years above the instantaneous maximum NAL, most recently RY 2024 · 1 303(d) listing · association: derived nearby in watershed (high 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