| Water Body Name: | San Gregorio Creek |
| Water Body ID: | CAR2023001419980929144335 |
| Water Body Type: | River & Stream |
DECISION ID |
89331 |
Region 2 |
San Gregorio Creek |
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| Pollutant: | Indicator Bacteria |
| Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Sources: | A Source Unknown |
| Expected TMDL Completion Date: | 2019 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for removal from the section 303(d) list under section 4.3 of the Listing Policy. Under section 4.3 a single line of evidence is necessary to assess delisting status. One line of evidence is available in the administrative record to assess this pollutant. A large number of samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. High percentages of samples exceeded the total and fecal coliform water quality objectives and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 1771 | ||||
| Pollutant: | Coliform Bacteria | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Water Contact Recreation | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PATHOGEN MONITORING | ||||
| Data Used to Assess Water Quality: | Fifty-six samples for total coliform, 23 samples for fecal coliform, 22 samples for E. coli. Basin Plan objectives violated in 2% samples for total coliform maximum. Objectives violated in 73% samples for total coliform median. Basin Plan objectives violated in 26% samples for fecal coliform geomean. Objectives violated in 43% samples for fecal coliform in dry-weather months. E. coli data show 45% samples for total coliform maximum designated beach violated the Basin Plan Objectives. Basin Plan objectives violated in 45% samples for E. coli maximum moderately-used beach, violated in 18% samples for maximum lightly-used beach and violated in 45% samples for maximum infrequently-used beach, in dry weather months (SWRCB, 2003). | ||||
| Data Reference: | Placeholder reference 2006 303(d) | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | Basin Plan objectives (SFBRWQCB, 1995)
Fecal coliform Log mean <200 MPN/100ml 90th percentile <400 MPN/100ml Total coliform Log mean <240 MPN/100ml 90th percentile >10,000 MPN/100ml |
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| Objective/Criterion Reference: | Placeholder reference 2006 303(d) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | Data was spatially collected. | ||||
| Temporal Representation: | Data was collected from 9/28/98-10/31/00. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | San Mateo County Environmental Health Dept. Beach Monitoring, Surfrider data/lab QA/QC used. Data evaluation was based on USEPA guidelines for 305(b) reports, that uses a hierarchy of water quality data levels. Only data of higher overall level of information (Levels 3 and 4) were used to list a water body. | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
89245 |
Region 2 |
San Gregorio Creek |
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| Pollutant: | Ammonia (Unionized) | Nitrogen, ammonia (Total Ammonia) |
| Final Listing Decision: | Do Not List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | These pollutants are being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of twelve samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 28068 | ||||
| Pollutant: | Ammonia (Unionized) | Nitrogen, ammonia (Total Ammonia) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 12 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | SWAMP collected twelve water samples that were analyzed for ammonia and un-ionized ammonia. None of them exceeded the evaluation criteria. | ||||
| Data Reference: | Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The San Francisco Bay Regional Water Quality Board Basin Plan states all waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. This objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
The San Francisco Bay Regional Water Quality Board Basin Plan stated that the discharge of wastes shall not cause receiving water to contain concentrations of un-ionized ammonia in excess of 0.025mg/l annual median. |
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| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2) | ||||
| Evaluation Guideline: | For Total Ammonia: EPA's Lifetime Health advisory level for total ammonia is 30.0 mg/L as stated on page 8 of the 2006 edition of the drinking water standards and health advisories. This Advisory Level is defined as "the concentration of a chemical in drinking water that is not expected to cause any adverse noncarcinogenic effects for up to ten days of exposure." | ||||
| Guideline Reference: | 2006 edition of the drinking water standards and health advisories. EPA 822-R-03-013 | ||||
| Spatial Representation: | Water samples were collected from four monitoring sites. Two sites (SGR010 and SGR040) represent the mainstem of San Gregorio Creek. SGR080 is located at the confluence with La Honda Ck and SGR090 at the confluence with Alpine Creek. | ||||
| Temporal Representation: | Samples were collected during dry, spring and wet seasons of 2002. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | The QA was in compliance with SWAMP Quality Assurance Management Plan. | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
77537 |
Region 2 |
San Gregorio Creek |
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| Pollutant: | Cadmium |
| Final Listing Decision: | Do Not List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of six samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 27988 | ||||
| Pollutant: | Cadmium | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 6 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | SWAMP collected six water samples from two locations in San Gregorio Creek. Cadmium concentrations were below the water quality objectives in all 6 samples. | ||||
| Data Reference: | Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The objective in the Basin Plan is expressed by formulas where H=ln (hardness) as CaCO3 in mg/l: The four-day average objective for cadmium is e (exp 0.7852H - 3.490). This is 1.1 ug/l at a hardness of 100mg/l as CaCO3. The one hour objective is e (exp 1.128H - 3.828). This is 3.9ug/l at a hardness of 100mg/l as CaCO3. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | The samples were collected from two monitoring locations (SGR010 and SGR080). | ||||
| Temporal Representation: | The samples were collected during wet spring and dry seasons of 2002. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | The QA/QC procedure was in compliance with Surface Water Ambient Monitoring Program's (SWAMP) Quality Assurance Management Plan (QAMP). | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
77461 |
Region 2 |
San Gregorio Creek |
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| Pollutant: | Copper | Lead | Nickel | Silver | Zinc |
| Final Listing Decision: | Do Not List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | These pollutants are being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of six samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 27935 | ||||
| Pollutant: | Copper | Lead | Nickel | Silver | Zinc | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 6 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | San Gregorio Creek was monitored as part of SWAMP assessment. None of the six samples exceeded the water quality objectives for copper, lead, nickel, silver and zinc. | ||||
| Data Reference: | Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Table 3-4 in the Basin Plan (2007) lists freshwater water quality objectives for toxic pollutants: copper - 9.0 ug/L, lead - 2.5 ug/L; nickel - 52 ug/L, silver - 3.4 ug/L and zinc - 120 ug/L. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board | ||||
| Spatial Representation: | The samples were collected from two monitoring sites: SGR010 the most downstream location, and SGR080 at the mid section of San Gregorio Creek. | ||||
| Temporal Representation: | The samples were collected from three different seasons, dry, wet and spring of 2002. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | The Quality Control is is conducted in accordance with SWAMP's Quality Management Plan of 2002. | ||||
| QAPP Information Reference(s): | |||||
DECISION ID |
70814 |
Region 2 |
San Gregorio Creek |
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| Pollutant: | Sedimentation/Siltation |
| Final Listing Decision: | List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Sources: | A Source Unknown |
| Expected TMDL Completion Date: | 2013 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed. |
| Regional Board Decision Recommendation: | This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current. The decision has not changed. |
| State Board Review of Regional Board Conclusion and Recommendation: | |
| State Board Decision Recommendation: | After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. |
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| LOE ID: | 3853 | ||||
| Pollutant: | Sedimentation/Siltation | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 0 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Not Specified | ||||
| Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. | ||||
| Data Reference: | Placeholder reference pre-2006 303(d) | ||||
| SWAMP Data: | Non-SWAMP | ||||
| Water Quality Objective/Criterion: | Unspecified | ||||
| Objective/Criterion Reference: | Placeholder reference pre-2006 303(d) | ||||
| Evaluation Guideline: | Unspecified | ||||
| Guideline Reference: | Placeholder reference pre-2006 303(d) | ||||
| Spatial Representation: | Unspecified | ||||
| Temporal Representation: | Unspecified | ||||
| Environmental Conditions: | Unspecified | ||||
| QAPP Information: | Unspecified | ||||
| QAPP Information Reference(s): | |||||