Arroyo Seco subwatershed (Alameda County, tributary to Arroyo Las Positas)
2026 303(d) list Waterbody ID CAR2043009020210603047098 River & Stream Region 2 · San Francisco Bay
At a glance
- 2026 listing Evidence: State-published
- On the 2026 303(d) list · 3 Appendix A decisions
- Category 5: a TMDL is required
- What a listing means
- Pollutants and stressors
- 3 pollutants in 3 Appendix A categories
- Nutrients (1) · Other Cause (1) · Total Toxics (1)
- Listing decisions
- TMDL information Evidence: State-published
- 3 decisions with a TMDL requirement status
- Status codes as published: 5A
- TMDL details
- Industrial stormwater facilities
- 0 report it as their receiving water Evidence: identification corroborated
- 78 within 1 km Evidence: geographic proximity
- Neither count establishes a discharge · Facilities
What a 303(d) listing means
The Clean Water Act section 303(d) list names waters that do not meet water quality standards for one or more pollutants or stressors. California publishes it in the Integrated Report; this page shows the 2026 decisions from Appendix A as published.
- A listing describes the condition of the waterbody. It does not identify which sources cause the impairment, and it does not by itself place a requirement on any particular facility.
- Listed waters do not all have the same status. The Integrated Report category says how an impairment is being addressed: 5, a TMDL is required; 4a, addressed by a USEPA-approved TMDL; 4b, addressed by other pollution control requirements; 4c, impairment not caused by a pollutant. This waterbody's decisions are in category 5.
- TMDL requirement status values (such as 5A or 5B) are shown exactly as published in Appendix A.
2026 listing status Evidence: State-published
- On the 2026 303(d) list
- Yes
- Appendix A decisions
- 3
- Integrated Report category
- 5 (a TMDL is required)
- Listing cycle
- 2026
- State Board adoption
- 2026-02-03 (Resolution 2026-0005)
- USEPA approval
- not confirmed — submittal letter to USEPA published; no approval found on the report page (checked 2026-10-22)
- Regional Water Board
- 2 — San Francisco Bay
Published by the State Water Resources Control Board (2026 California Integrated Report, Appendix A). Listing status is taken from Appendix A only. A listing describes the condition of this waterbody, not of any facility.
Location
Loading the waterbody shape…
Open this area on the statewide map · Browse impaired waters
Listing decisions and pollutants Evidence: State-published
Grouped by the Pollutant Category published in Appendix A. Pollutant names, categories and decisions are exactly as published.
Nutrients (1 decision)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Ammonia | Nutrients | 5 | List on 303(d) list (TMDL required list) | Revised | A Source Unknown | 150853 |
Other Cause (1 decision)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Benthic Community Effects | Other Cause | 5 | List on 303(d) list (TMDL required list) | Revised | A Source Unknown | 154154 |
Total Toxics (1 decision)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Toxicity | Total Toxics | 5 | List on 303(d) list (TMDL required list) | Revised | A Source Unknown | 144487 |
TMDL information Evidence: State-published
| Pollutant | TMDL requirement status | TMDL project | Priority | USEPA approval of TMDL | Expected attainment |
|---|---|---|---|---|---|
| Ammonia | 5A | — | Low | — | — |
| Benthic Community Effects | 5A | — | Low | — | — |
| Toxicity | 5A | — | Low | — | — |
This is TMDL information for the waterbody. It does not establish that a TMDL applies to any particular facility. Facility-specific TMDL requirements recorded in SMARTS appear on facility pages and are not linked to this waterbody until reviewed.
HUC12 watersheds
Published with the listing Evidence: publisher-reported
- Arroyo Seco 180500040201
- Lower Arroyo Las Positas 180500040203
Overlapping the waterbody's shape Evidence: spatial
- Arroyo Seco 180500040201 also published
- Upper Arroyo Las Positas 180500040202
- Lower Arroyo Las Positas 180500040203 also published
Industrial stormwater facilities
Evidence: identification corroborated
Shows: the facility named this waterbody as its receiving water in SMARTS, and the name and the facility's location are consistent with it. Does not establish: a discharge pathway, a discharge of any pollutant, or a cause of the listing.
Evidence: geographic proximity
Shows: the facility's reported location is within 1 km of the waterbody's mapped shape. Does not establish: that the facility discharges to this waterbody, or any other relationship.
Report this waterbody as their receiving water Evidence: identification corroborated
No facility's reported receiving water is identified as this waterbody.
Within 1 km of a facility's reported location Evidence: geographic proximity
Spatial proximity only; discharge pathway not established. Being near this waterbody does not mean a facility discharges to it.
| Facility | WDID | Status | Distance | Map |
|---|---|---|---|---|
| Digitaltest | 2 01NEC007114 | Active | 45 m | map |
| Protek Manufacturing | 2 01NEC012004 | Active | 56 m | map |
| Del Cielo Brewing Co | 2 01NEC014419 | Active | 58 m | map |
| TransPak Inc | 2 01NEC009725 | Active | 95 m | map |
| Penumbra Livermore | 2 01NEC008795 | Active | 109 m | map |
| Shadow Puppet Brewing Company | 2 01NEC001966 | Active | 112 m | map |
| Standard Register Livermore | 2 01NEC002757 | Terminated | 139 m | map |
| Tri Valley Trans | 2 01I005595 | Terminated | 151 m | map |
| Pacific Steel Group | 2 01I028569 | Terminated | 186 m | map |
| Gas Recovery Systems LLC | 2 01I018745 | Terminated | 191 m | map |
| Joshua 18 Transport | 2 01NNA001468 | Undetermined | 197 m | map |
| Hill Farms | 2 01NNA001659 | No Action Required | 209 m | map |
| Custom Product Development Corporation | 2 01NEC009304 | Active | 217 m | map |
| Lawrence Livermore Nat Lab | 2 01I004546 | Terminated | 217 m | map |
| UOVO | 2 01NEC008782 | Terminated | 220 m | map |
| Uovo | 2 01NEC011621 | Active | 220 m | map |
| Sandia National Laboratories CA | 2 01I002598 | Active | 223 m | map |
| Household Hazardous Waste Fac | 2 01I009823 | Terminated | 254 m | map |
| Triangle Coatings Inc | 2 01I023331 | Terminated | 257 m | map |
| Triangle Coatings Inc | 2 01I026251 | Terminated | 257 m | map |
| Will-Store Super Storage | 2 01NNA002218 | No Action Required | 260 m | map |
| Pacon Mfg Inc | 2 01NEC009940 | Active | 272 m | map |
| VetEquip Inc | 2 01NEC011394 | Active | 272 m | map |
| The Last Factory | 2 01NEC010525 | Active | 275 m | map |
| Triple S Metal | 2 01I024434 | Active | 285 m | map |
| Ferrotec USA Corp | 2 01NEC011505 | Active | 324 m | map |
| Jifco Inc | 2 01I025437 | Active | 327 m | map |
| Caliber Cabinets Inc | 2 01NEC008933 | Active | 328 m | map |
| Custom Gear & Machine Incorporated | 2 01NEC000043 | Terminated | 347 m | map |
| Goza Gear Ink | 2 01NEC011754 | Active | 366 m | map |
| Gsl | 2 01I006576 | Terminated | 367 m | map |
| Big City Corvettes | 2 01NNA001007 | No Action Required | 394 m | map |
| HB Engineering | 2 01NEC010718 | Active | 406 m | map |
| Harris Rebar Northern California Inc | 2 01I019083 | Terminated | 412 m | map |
| 580 Fabrication | 2 01NEC008552 | Terminated | 428 m | map |
| Omega Road Winery | 2 01NEC010485 | Active | 428 m | map |
| STModel | 2 01NEC010973 | Active | 434 m | map |
| LLNL Livermore Site | 2 01I025682 | Active | 440 m | map |
| FormFactor Inc | 2 01I020426 | Terminated | 441 m | map |
| Ferrotec USA Corporation | 2 01NEC010478 | Terminated | 443 m | map |
| Thermal Press International | 2 01NEC012141 | Active | 448 m | map |
| Altair Microwave Inc | 2 01NEC009066 | Terminated | 459 m | map |
| Public Storage | 2 01NNA000841 | No Action Required | 466 m | map |
| Livermore - Patterson Pass | 2 01NNA000719 | No Action Required | 469 m | map |
| Occasio Winery | 2 01NEC000362 | Active | 498 m | map |
| Favalora Vineyards Winery | 2 01NEC009803 | Active | 498 m | map |
| Nottingham Cellars | 2 01NEC000375 | Terminated | 507 m | map |
| MS CARITA INC | 2 01NEC011104 | Active | 508 m | map |
| Free Range Flower Wienry | 2 01NEC010091 | Terminated | 531 m | map |
| Induspac California Inc | 2 01NEC010675 | Terminated | 567 m | map |
78 facilities, nearest first. Page 1 of 2: next
Sources and provenance
| Information | Source | Retrieved |
|---|---|---|
| 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 (facility_huc12/1, proximity/1, receiving_water/2, tmdl_reference/1, waterbody_huc12_ovl/1, waterbody_huc12_pub/1).
Integrated Report categories: 5, a TMDL is required; 4a, addressed by a USEPA-approved TMDL; 4b, addressed by other pollution control requirements; 4c, impairment not caused by a pollutant.