Klamath River HU, Middle HA, Iron Gate Dam to Scott River
2026 303(d) list Waterbody ID CAR1053505320011215015907 River & Stream Region 1 · North Coast
At a glance
- 2026 listing Evidence: State-published
- On the 2026 303(d) list · 9 Appendix A decisions
- Category 5: a TMDL is required
- What a listing means
- Pollutants and stressors
- 9 pollutants in 4 Appendix A categories
- Metals (1) · Nutrients (2) · Other Cause (4) · Sediment (2)
- Listing decisions
- TMDL information Evidence: State-published
- 9 decisions with a TMDL requirement status; 5 name a TMDL project
- Status codes as published: 5A, 5B
- TMDL details
- Industrial stormwater facilities
- 0 report it as their receiving water Evidence: identification corroborated
- 2 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
- 9
- 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
- 1 — North Coast
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
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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.
Metals (1 decision)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Aluminum | Metals | 5 | Do Not Delist from 303(d) list (TMDL required list) | Revised | A Source Unknown | 74060 |
Nutrients (2 decisions)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Nutrients | Nutrients | 5 | Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL) | Revised | Agriculture Drainage/Filling Of Wetlands Grazing-Related Sources Irrigated Crop Production Logging Road Construction/Maintenance Road Construction Silviculture | 168841 |
| Organic Enrichment/Low Dissolved Oxygen | Nutrients | 5 | Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL) | Revised | Agriculture Drainage/Filling Of Wetlands Grazing-Related Sources Irrigated Crop Production Logging Road Construction/Maintenance Road Construction Silviculture | 73558 |
Other Cause (4 decisions)
| 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 | 169295 |
| Cyanobacteria hepatotoxic microcystins | Other Cause | 5 | List on 303(d) list (being addressed by USEPA approved TMDL) | Original | Agriculture Grazing-Related Sources Habitat Modification Irrigated Crop Production Logging Road Construction/Maintenance Road Construction Silviculture | 75113 |
| Microcystins | Other Cause | 5 | List on 303(d) list (being addressed by USEPA approved TMDL) | Revised | A Source Unknown | 161484 |
| Temperature, water | Other Cause | 5 | Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL) | Revised | Agriculture Drainage/Filling Of Wetlands Flow Alteration/Regulation/Modification Grazing-Related Sources Irrigated Crop Production Logging Road Construction/Maintenance Removal of Riparian Vegetation Road Construction Silviculture | 155230 |
Sediment (2 decisions)
| Pollutant | Pollutant category | Category | Final listing decision | Decision status | Sources | Decision ID |
|---|---|---|---|---|---|---|
| Sediment | Sediment | 5 | Do Not Delist from 303(d) list (TMDL required list) | Revised | A Source Unknown | 168845 |
| Turbidity | Sediment | 5 | List on 303(d) list (TMDL required list) | Revised | A Source Unknown | 157105 |
TMDL information Evidence: State-published
| Pollutant | TMDL requirement status | TMDL project | Priority | USEPA approval of TMDL | Expected attainment |
|---|---|---|---|---|---|
| Aluminum | 5A | — | Low | — | — |
| Benthic Community Effects | 5A | — | Low | — | — |
| Cyanobacteria hepatotoxic microcystins | 5B | Klamath River Nutrients, Temperature, DO, and Microcystin. | — | 2010-12-28 | — |
| Microcystins | 5B | Klamath River Nutrients, Temperature, DO, and Microcystin. | — | 2010-12-28 | — |
| Nutrients | 5B | Klamath River Nutrients, Temperature, DO, and Microcystin. | — | 2010-12-28 | — |
| Organic Enrichment/Low Dissolved Oxygen | 5B | Klamath River Nutrients, Temperature, DO, and Microcystin. | — | 2010-12-28 | — |
| Sediment | 5A | — | Low | — | — |
| Temperature, water | 5B | Klamath River Nutrients, Temperature, DO, and Microcystin. | — | 2010-12-28 | — |
| Turbidity | 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
- Upper Cottonwood Creek 180102060601
- Willow Creek 180102060703
- Williams Creek-Klamath River 180102060704
- Humbug Creek 180102060801
- Ash Creek-Klamath River 180102060802
- Cow Creek-Grouse Creek 180102060901
- Barkhouse Creek 180102061001
- Little Humbug Creek-Klamath River 180102061002
- McKinney Creek-Klamath River 180102061003
- Kohl Creek-Klamath River 180102061005
Overlapping the waterbody's shape Evidence: spatial
- Upper Cottonwood Creek 180102060601 also published
- Middle Cottonwood Creek 180102060603
- Lower Cottonwood Creek 180102060604
- Bogus Creek 180102060701
- Brush Creek-Klamath River 180102060702
- Willow Creek 180102060703 also published
- Williams Creek-Klamath River 180102060704 also published
- Humbug Creek 180102060801 also published
- Ash Creek-Klamath River 180102060802 also published
- Empire Creek-Klamath River 180102060803
- Cow Creek-Grouse Creek 180102060901 also published
- Hungry Creek-Beaver Creek 180102060902
- West Fork Beaver Creek 180102060903
- Dutch Creek-Beaver Creek 180102060904
- Barkhouse Creek 180102061001 also published
- Little Humbug Creek-Klamath River 180102061002 also published
- McKinney Creek-Klamath River 180102061003 also published
- Kohl Creek-Klamath River 180102061005 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 |
|---|---|---|---|---|
| Grass Lake Quarry | 1 47I022417 | Terminated | 82 m | map |
| Hornbrook Batch Plant | 1 47I024906 | Terminated | 100 m | map |
2 facilities, nearest first.
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.