Oso Creek Water Reclamation Plant
Terminated WDID 9 30I005772 Mission Viejo, Orange County Region 9 · San Diego
At a glance
- Permit Evidence: SMARTS record
- Terminated Industrial
- Notice of Intent (WDID code I) · Permits and applications
- Location Evidence: facility-reported
- Mission Viejo, Orange County
- Region 9 · San Diego · Location · Statewide map
- Receiving water
- Oso Creek (as reported by the facility)
- Evidence: candidate, awaiting review Details
- Identified receiving water on the 2026 303(d) list
- Not established
- Shown only when the reported receiving water is identified and corroborated.
- 2026 Integrated Report waters within 1.0 km Evidence: geographic proximity
- 1 waterbody; 1 on the 2026 303(d) list
- Proximity only; not a discharge pathway · Nearby waterbodies
- Monitoring results Evidence: facility-reported
- 247 distinct results, 7 reporting years (2015 to 2021)
- Most recent sample Dec 14, 2021 · Monitoring
- Compliance and enforcement records Evidence: SMARTS record
- 2 inspections · 2 violation records · 2 enforcement actions
- Counts as published in SMARTS; not a compliance determination · Details
Each label shows where a statement comes from. How to read the labels.
Overview and location
Reported facility location HUC12 watershed Corroborated receiving water 2026 Integrated Report waterbodies nearby
Reported location Evidence: facility-reported
- Coordinates
- 33.5963, -117.65583
- Precision
- 4 decimal places
- Shared point
- No
- Matches application record
- same
Facility location as reported by the discharger in SMARTS; not a discharge point or outfall.
- Facility address
- 27204 La Paz Rd, Mission Viejo 92692
- Regional Water Board
- 9 — San Diego
HUC12 watershed Evidence: spatial
- Arroyo Trabuco HUC12 180703010103
The facility's reported location lies within this HUC12 watershed (spatial derivation); it is not a discharge location.
Permits and applications Evidence: SMARTS record
Current permit record
- Permit type
- Industrial
- Application type
- Notice of Intent (WDID code I)
- Status
- Terminated
- Operator
- Santa Margarita Water District
- Primary industry (SIC)
- 4952-Sewerage Systems
- Application ID
- 214862
- NOI processed
- Apr 07, 1992
- Termination effective
- Mar 04, 2022
- Last certified
- Jun 01, 2015
- Facility size
- 2 Acres
Retrieved from SMARTS Oct 20, 2026. Verify against SMARTS before relying on it.
Permit history
| Application | Type | Status | Processed | Terminated | Certified |
|---|---|---|---|---|---|
| 214862 | Industrial | Terminated | Apr 07, 1992 | Mar 04, 2022 | Jun 01, 2015 |
Every storm water application SMARTS records for this WDID, newest first (1).
Receiving water
- Reported by the facility Evidence: facility-reported
- Oso Creek
- Discharges directly / indirectly
- N / N (as answered in the permit application)
Evidence: not confirmed Evidence: candidate, awaiting review Awaiting review
Receiving-water text as reported by the discharger in SMARTS; no waterbody identification has been confirmed.
Why it is not confirmed (1)
- C1 name is only a prefix of official names
2 official waterbodies share this name; none is assigned without review.
Impaired waters and TMDLs
Two kinds of information, kept apart: 2026 Integrated Report waterbodies near the reported location (geographic proximity only), and TMDL records that SMARTS lists for this facility. Neither establishes where the facility discharges; see Receiving water for the facility's own statement.
Nearby waterbodies Evidence: geographic proximity
Spatial proximity only; discharge pathway not established. Being near a waterbody does not mean the facility discharges to it.
| Waterbody (2026 Integrated Report) | Distance | 2026 303(d) list | Appendix A decisions |
|---|---|---|---|
| Oso Creek (lower) CAR9012000020010831154628 | 16 m | listed | 4 |
Waterbodies within 1.0 km of the reported facility location. Method proximity/1.
SMARTS TMDL records Evidence: SMARTS-reported
No TMDL records for this facility in the SMARTS TMDL export.
Reported monitoring results Evidence: facility-reported
Numeric Action Level (NAL) screening is being independently validated and is not shown. Nothing on this page states whether a result exceeded a NAL.
247 distinct measurements across 6 parameters, most recent sample Dec 14, 2021.
By reporting year
| Reporting year (July–June) | Distinct results | Parameters | With several versions | First sample | Last sample |
|---|---|---|---|---|---|
| 2021 | 24 | 6 | 0 | Oct 25, 2021 | Dec 14, 2021 |
| 2020 | 12 | 6 | 0 | Mar 03, 2021 | Mar 03, 2021 |
| 2019 | 48 | 6 | 0 | Nov 27, 2019 | Apr 06, 2020 |
| 2018 | 48 | 6 | 0 | Nov 29, 2018 | Jan 31, 2019 |
| 2017 | 24 | 6 | 0 | Jan 09, 2018 | Mar 22, 2018 |
| 2016 | 48 | 6 | 0 | Oct 24, 2016 | Jan 09, 2017 |
| 2015 | 43 | 6 | 0 | Sep 15, 2015 | Mar 07, 2016 |
By parameter
| Parameter | Units | Measurements | Below detection | First sample | Last sample | Results |
|---|---|---|---|---|---|---|
| Nitrogen, Total (as N) | mg/L | 42 | 0 | Sep 15, 2015 | Dec 14, 2021 | Results |
| pH | SU | 42 | 0 | Sep 15, 2015 | Dec 14, 2021 | Results |
| Phosphorus, Total (as P) | mg/L | 42 | 0 | Sep 15, 2015 | Dec 14, 2021 | Results |
| Total Suspended Solids (TSS) | mg/L | 42 | 0 | Sep 15, 2015 | Dec 14, 2021 | Results |
| Total Coliform | MPN/100 mL | 40 | 2 | Dec 11, 2015 | Dec 14, 2021 | Results |
| Oil and Grease | mg/L | 39 | 24 | Dec 11, 2015 | Dec 14, 2021 | Results |
All results (247 distinct rows)
| Sample date | Parameter | Result | Units | Location type | Event | Method | Report | Versions |
|---|---|---|---|---|---|---|---|---|
| Dec 14, 2021 | Nitrogen, Total (as N) | 3.2 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1173444 | |
| Dec 14, 2021 | Nitrogen, Total (as N) | 2.15 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1173444 | |
| Dec 14, 2021 | Oil and Grease | ND | mg/L | Effluent | Qualifying Storm Event | E1664A | 1173444 | |
| Dec 14, 2021 | Oil and Grease | ND | mg/L | Effluent | Qualifying Storm Event | E1664A | 1173444 | |
| Dec 14, 2021 | pH | 8.46 | SU | Effluent | Qualifying Storm Event | pH_Field | 1173444 | |
| Dec 14, 2021 | pH | 8.42 | SU | Effluent | Qualifying Storm Event | pH_Field | 1173444 | |
| Dec 14, 2021 | Phosphorus, Total (as P) | .89 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1173444 | |
| Dec 14, 2021 | Phosphorus, Total (as P) | .44 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1173444 | |
| Dec 14, 2021 | Total Coliform | 70 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1173444 | |
| Dec 14, 2021 | Total Coliform | 100 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1173444 | |
| Dec 14, 2021 | Total Suspended Solids (TSS) | 20 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1173444 | |
| Dec 14, 2021 | Total Suspended Solids (TSS) | 20.4 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1173444 | |
| Oct 25, 2021 | Nitrogen, Total (as N) | 2.58 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1173441 | |
| Oct 25, 2021 | Nitrogen, Total (as N) | 2.48 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1173441 | |
| Oct 25, 2021 | Oil and Grease | ND | mg/L | Effluent | Qualifying Storm Event | E1664A | 1173441 | |
| Oct 25, 2021 | Oil and Grease | 2 | mg/L | Effluent | Qualifying Storm Event | E1664A | 1173441 | |
| Oct 25, 2021 | pH | 8.59 | SU | Effluent | Qualifying Storm Event | pH_Field | 1173441 | |
| Oct 25, 2021 | pH | 8.5 | SU | Effluent | Qualifying Storm Event | pH_Field | 1173441 | |
| Oct 25, 2021 | Phosphorus, Total (as P) | .65 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1173441 | |
| Oct 25, 2021 | Phosphorus, Total (as P) | .22 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1173441 | |
| Oct 25, 2021 | Total Coliform | 190 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1173441 | |
| Oct 25, 2021 | Total Coliform | 90 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1173441 | |
| Oct 25, 2021 | Total Suspended Solids (TSS) | 8 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1173441 | |
| Oct 25, 2021 | Total Suspended Solids (TSS) | 11 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1173441 | |
| Mar 03, 2021 | Nitrogen, Total (as N) | 4.23 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1150764 | |
| Mar 03, 2021 | Nitrogen, Total (as N) | 3.42 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1150764 | |
| Mar 03, 2021 | Oil and Grease | 3.4 | mg/L | Effluent | Qualifying Storm Event | E1664A | 1150764 | |
| Mar 03, 2021 | Oil and Grease | 2.7 | mg/L | Effluent | Qualifying Storm Event | E1664A | 1150764 | |
| Mar 03, 2021 | pH | 7.86 | SU | Effluent | Qualifying Storm Event | pH_Field | 1150764 | |
| Mar 03, 2021 | pH | 7.46 | SU | Effluent | Qualifying Storm Event | pH_Field | 1150764 | |
| Mar 03, 2021 | Phosphorus, Total (as P) | 1.75 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1150764 | |
| Mar 03, 2021 | Phosphorus, Total (as P) | .7 | mg/L | Effluent | Qualifying Storm Event | A4500PE | 1150764 | |
| Mar 03, 2021 | Total Coliform | 600 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1150764 | |
| Mar 03, 2021 | Total Coliform | 800 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1150764 | |
| Mar 03, 2021 | Total Suspended Solids (TSS) | 170 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1150764 | |
| Mar 03, 2021 | Total Suspended Solids (TSS) | 80 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1150764 | |
| Apr 06, 2020 | Nitrogen, Total (as N) | 2.9 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1105902 | |
| Apr 06, 2020 | Nitrogen, Total (as N) | 2.65 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1105902 | |
| Apr 06, 2020 | Oil and Grease | ND | mg/L | Effluent | Qualifying Storm Event | E1664A | 1105902 | |
| Apr 06, 2020 | Oil and Grease | ND | mg/L | Effluent | Qualifying Storm Event | E1664A | 1105902 | |
| Apr 06, 2020 | pH | 8.18 | SU | Effluent | Qualifying Storm Event | A4500HB | 1105902 | |
| Apr 06, 2020 | pH | 8.05 | SU | Effluent | Qualifying Storm Event | A4500HB | 1105902 | |
| Apr 06, 2020 | Phosphorus, Total (as P) | .45 | mg/L | Effluent | Qualifying Storm Event | E365.1 | 1105902 | |
| Apr 06, 2020 | Phosphorus, Total (as P) | .28 | mg/L | Effluent | Qualifying Storm Event | E365.1 | 1105902 | |
| Apr 06, 2020 | Total Coliform | 7000 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1105902 | |
| Apr 06, 2020 | Total Coliform | 11000 | MPN/100 mL | Effluent | Qualifying Storm Event | A9222B | 1105902 | |
| Apr 06, 2020 | Total Suspended Solids (TSS) | 28.6 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1105902 | |
| Apr 06, 2020 | Total Suspended Solids (TSS) | 18.4 | mg/L | Effluent | Qualifying Storm Event | A2540D | 1105902 | |
| Mar 10, 2020 | Nitrogen, Total (as N) | 4.05 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1105900 | |
| Mar 10, 2020 | Nitrogen, Total (as N) | 6.6 | mg/L | Effluent | Qualifying Storm Event | A4500NB | 1105900 |
Results are shown exactly as reported by the discharger. Identical rows repeated in the State's export are shown once. Where the export contains different versions of the same sample and parameter, each version is listed and flagged. Details.
Compliance and enforcement records Evidence: SMARTS record
These are records as the State Water Board publishes them in SMARTS, with the source's own types and statuses. They are not a compliance determination or rating. A record listed here is not proof of a violation beyond what the source states, and the absence of records does not establish compliance.
| Record type | Records | As published | Dates | Retrieved | List |
|---|---|---|---|---|---|
| Violations | 2 | 2 Violation · 0 Potential (preliminary) · 0 Dismissed | Jul 02, 1999 – Jul 02, 1999 | Oct 21, 2026 | All violations |
| Enforcement actions | 2 | 2 issued · 0 draft · 0 withdrawn, rescinded or superseded | Oct 14, 1999 – Oct 15, 1999 | Oct 21, 2026 | All actions |
| Inspections | 2 | inspections, not findings | Nov 17, 2004 – Aug 02, 2018 | Oct 21, 2026 | All inspections |
| Annual reports | 7 | certified reports (contents not shown) | 2015 – 2021 | Oct 21, 2026 | All reports |
| Water-quality-based corrective action reports | 0 | reports, by parameter | — | Oct 21, 2026 |
Each record type is counted by its own SMARTS identifier. A violation and the enforcement action that cites it are two records in two lists; they are never added together.
Chronological record history (13 records, newest first)
| Date | Record | ID | Type or purpose | Status as published | Detail |
|---|---|---|---|---|---|
| Mar 04, 2022 | Annual reports | 1114666 | Annual report 2021 | — | |
| Jul 15, 2021 | Annual reports | 1070763 | Annual report 2020 | — | |
| Jul 15, 2021 | Annual reports | 988180 | Annual report 2019 | — | |
| Jul 12, 2019 | Annual reports | 955812 | Annual report 2018 | — | |
| Aug 02, 2018 | Inspections | 2039071 | B Type compliance | — | No Further Action |
| Jul 13, 2018 | Annual reports | 941236 | Annual report 2017 | — | |
| Jul 14, 2017 | Annual reports | 880610 | Annual report 2016 | — | |
| Jul 12, 2016 | Annual reports | 839337 | Annual report 2015 | — | |
| Nov 17, 2004 | Inspections | 336924 | B Type compliance | — | |
| Oct 15, 1999 | Enforcement actions | 233443 | NOV (Notice of Violation) | Active | UNKNOWN |
| Oct 14, 1999 | Enforcement actions | 234207 | NOV (Notice of Violation) | Historical | UNKNOWN |
| Jul 02, 1999 | Violations | 178544 | Deficient Report | Violation | Inspection |
| Jul 02, 1999 | Violations | 216924 | Deficient Report | Violation | Inspection |
Sources and provenance
| Information | Source | Retrieved or published |
|---|---|---|
| Permit, location, receiving-water text | SMARTS Industrial Application Specific Data | Oct 20, 2026 |
| Permit history | SMARTS Storm Water Applications | Oct 20, 2026 |
| Monitoring results | SMARTS Industrial Parameter Data | Oct 20, 2026 |
| Watershed Boundary Dataset HU2 GeoPackages 15, 16, 18 (WBDHU12) | USGS | 2026-10-22 |
| 2026 California Integrated Report, Appendix A: 2026 303(d) List (final) | SWRCB | 2026-10-22 |
| Final_2026_Rivers_and_Streams + Final_2026_Lakes_and_Reservoirs (FeatureServer 0) | SWRCB GIS | 2026-10-22 |
| SMARTS TMDL requirements | SMARTS | 2026-10-21 |
Relationships computed 2026-10-22 with methods facility_huc12/1, proximity/1, receiving_water/2, tmdl_reference/1, waterbody_huc12_ovl/1, waterbody_huc12_pub/1; proximity threshold 1.0 km.
How to read the evidence labels
- Evidence: SMARTS record Evidence: facility-reported Information as published in SMARTS or reported by the discharger.
- Evidence: identification corroborated The reported receiving-water name identifies one official waterbody and the facility's location is consistent with it. It does not establish a discharge pathway.
- Evidence: candidate, awaiting review Evidence: not confirmed The reported name could match one or more official waterbodies, but no identification has been confirmed; nothing is assigned without review.
- Evidence: spatial Evidence: geographic proximity Derived from the reported location only.
- Evidence: SMARTS-reported Source records whose links to official references are not yet reviewed.
- Evidence: unavailable The information could not be loaded or is not in the sources.
Records are shown as published and are not compliance determinations. How geographic context is derived.