Draft California 2016 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Baxter Creek (Contra Costa County)
Water Body ID:	CAR2066001320080626144111
Water Body Type:	River & Stream


DECISION ID	35258	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Trash
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with action other than TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2012)
Revision Status	Revised
Sources:	Source Unknown
Expected Attainment Date:	2029
Implementation Action Other than TMDL:	This trash listing will be addressed by implementing the trash control provisions of the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California through the NPDES MS4 permit applicable to this waterbody.
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.11 of the Listing Policy. Under section 3.11, listing may be proposed based on the situation-specific weight of evidence. Two lines of evidence is available in the administrative record to assess this pollutant. The lines of evidence consist of interpretation of data from field visits/trash surveys conducted according to the Rapid Trash Assessment (RTA) methodology to assess both non-contact recreation and wildlife beneficial uses. Based on the readily available trash assessment data for this waterbody, the weight of evidence indicates that there is sufficient justification available in favor of placing this water segment-pollutant combination to the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. Data have been evaluated that supports this decision. 2. The Rapid Trash Assessment methodology results showed that this waterbody had level of trash parameter scores in the poor category (indicating impairment of non-contact water recreational beneficial uses) at two locations on five different dates. This waterbody also had threat to aquatic life parameter scores in the poor category (indicating threat to Wildlife Habitat beneficial uses) at three different locations on five different dates. 3. This waterbody is considered impaired by trash because there were exceedances of the evaluation guideline (poor condition category for the trash assessment metrics) in more than one location or on more than one date. 4. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 5. The data used satisfy the data quantity requirements of section 6.1 of the Policy. 6. This trash listing will be addressed by implementing the trash control provisions of the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California through the NPDES MS4 permit applicable to this waterbody.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

Line of Evidence (LOE) for Decision ID 35258, Trash	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

5212

Pollutant:

Trash

LOE Subgroup:

Pollutant-Nuisance

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Occurrence of conditions judged to cause impairment

Data Used to Assess Water Quality:

Data results were obtained through application the RTA methodology, developed by the Surface Water Ambient Monitoring Program (SWAMP). The RTA documents the total number and characteristics of pieces of trash per one hundred feet of stream or shoreline. The trash assessment protocol involves picking up and tallying all of the trash items found within the defined boundaries of a site. The tally results for level of trash (relating to REC2) and threat to aquatic life (relating to WILD) assessment parameters were considered for the listing determination. These results are available for field visits/trash surveys conducted in March, July, and November 2004 and June and August 2005 according to the Rapid Trash Assessment methodology. There were exceedances of the evaluation guideline (poor condition category for the trash assessment metric) in more than one location or on more than one date.

Data Reference:

A Rapid Trash Assessment Method Applied to Waters of the San Francisco Bay Region:Trash Measurement in Streams

Rapid Trash Assessment (RTA) data collected by the SF Bay Region Surface Water Ambient Monitoring Program from 2002-2005 and method description

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan prohibits discharge of Rubbish, refuse, bark, sawdust, or other solid wastes into surface waters or at any place where they would contact or where they would be eventually transported to surface waters, including flood plain areas.

The Basin Plan has a narrative objective for floating material, Waters shall not contain floating material, including solids, liquids, foams, and scum, in concentrations that cause nuisance or adversely affect beneficial uses.

The Basin Plan has a narrative objective for settleable material, Waters shall not contain substances in concentrations that result in the deposition of material that cause nuisance or adversely affect beneficial uses.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

If the Rapid Trash Assessment (RTA) Parameter 1 (Level of Trash) is in the poor condition category? (scores 0-5), REC2 is not supported. This level of trash distracts the eye on first glance, making the site unsuitable for recreation. The RTA defines poor condition for this parameter as follows, trash distracts the eye on first glance. Stream, bank surfaces, and immediate riparian zone contain substantial levels of litter and debris (>100 pieces). Evidence of site being used frequently by people: many cans, bottles, and food wrappers, blankets, clothing.

If the RTA Parameter 3 (Threat to Aquatic Life) is in the poor condition category (scores 0-5), then WILD is not supported. This level of trash is a large amount (>50 pieces) of transportable, persistent, buoyant litter that is detrimental to aquatic life. The RTA defines poor condition for this parameter as follows, large amount (>50 pieces) of transportable, persistent, buoyant litter such as: hard or soft plastics, balloons, Styrofoam, cigarette butts; toxic items such as batteries, lighters, or spray cans; large clumps of yard waste or dumped leaf litter; or large amount (>50 pieces) of settleable glass or metal.

Guideline Reference:

A Rapid Trash Assessment Method Applied to Waters of the San Francisco Bay Region:Trash Measurement in Streams

Spatial Representation:

RTA data were collected for this waterbody in three different locations in 2004 and 2005. Two locations scored in the poor condition category for the Level of Trash parameter associated with this beneficial use.

Temporal Representation:

RTA data were collected for this waterbody in March, July, and November in 2004 and June and August 2005.

Environmental Conditions:

QAPP Information:

For RTA trash assessment data to be considered, the data must have been collected by field operators that have received a 2-hour training in the Rapid Trash Assessment methodology.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 35258, Trash	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

5276

Pollutant:

Trash

LOE Subgroup:

Pollutant-Nuisance

Matrix:

Not Specified

Fraction:

None

Beneficial Use:

Wildlife Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Occurrence of conditions judged to cause impairment

Data Used to Assess Water Quality:

Data Reference:

A Rapid Trash Assessment Method Applied to Waters of the San Francisco Bay Region:Trash Measurement in Streams

Rapid Trash Assessment (RTA) data collected by the SF Bay Region Surface Water Ambient Monitoring Program from 2002-2005 and method description

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

If the Rapid Trash Assessment (RTA) Parameter 1 (Level of Trash) is in the poor condition category (scores 0-5), REC2 is not supported. This level of trash distracts the eye on first glance, making the site unsuitable for recreation. The RTA defines poor condition for this parameter as follows, trash distracts the eye on first glance. Stream, bank surfaces, and immediate riparian zone contain substantial levels of litter and debris (>100 pieces). Evidence of site being used frequently by people: many cans, bottles, and food wrappers, blankets, clothing.

If the RTA Parameter 3 (Threat to Aquatic Life) is in the poor condition category (scores 0-5), then WILD is not supported. This level of trash is a large amount (>50 pieces) of transportable, persistent, buoyant litter that is detrimental to aquatic life. The RTA defines poor condition for this parameter as follows, large amount (>50 pieces) of transportable, persistent, buoyant litter such as: hard or soft plastics, balloons, Styrofoam, cigarette butts; toxic items such as batteries, lighters, or spray cans; large clumps of yard waste or dumped leaf litter; or large amount (>50 pieces) of settleable glass or metal.

Guideline Reference:

A Rapid Trash Assessment Method Applied to Waters of the San Francisco Bay Region:Trash Measurement in Streams

Spatial Representation:

RTA data were collected for this waterbody in three different locations in 2004 and 2005. Three locations scored in the poor condition category for the Threat to Aquatic Life parameter associated with this beneficial use.

Temporal Representation:

RTA data were collected for this waterbody in March, July, and November in 2004 and June and August 2005.

Environmental Conditions:

QAPP Information:

For RTA trash assessment data to be considered, the data must have been collected by field operators that have received a 2-hour training in the Rapid Trash Assessment methodology.

QAPP Information Reference(s):


DECISION ID	44562	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Anthracene \| Benzo(a)anthracene \| Benzo(a)pyrene (3,4-Benzopyrene -7-d) \| Chrysene (C1-C4) \| DDD (Dichlorodiphenyldichloroethane) \| DDE (Dichlorodiphenyldichloroethylene) \| DDT (Dichlorodiphenyltrichloroethane) \| Dieldrin \| Endrin \| Fluoranthene \| Fluorene \| Heptachlor epoxide \| Lindane/gamma Hexachlorocyclohexane (gamma-HCH) \| Naphthalene \| PAHs (Polycyclic Aromatic Hydrocarbons) \| PCBs (Polychlorinated biphenyls) \| Phenanthrene \| Pyrene
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)(2012)
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 this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess these pollutants. Zero 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 one sample exceed the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 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.

Line of Evidence (LOE) for Decision ID 44562, Multiple Pollutants	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28638

Pollutant:

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentrations of anthracene, fluorene, napthalene, phenanthrene, benz(a)anthracene, benzo(a)pyrene, chrysene, fluoranthrene, pyrene, PAH (total), PCB (total), dieldrin, DDD/DDE/DDT, endrin, heptachlor epoxide, and HCH, gamma in one sediment sample collected in spring 2005 did not exceed the sediment quality guidelines.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) Anthracene - 845 ug/kg; Fluorene - 536 ug/kg; Naphthalene - 561 ug/kg;
Phenanthrene -1170 ug/kg; Benz(a)anthracene - 1050 ug/kg; Benzo(a)pyrene - 1450 ug/kg; Chrysene - 1290 ug/kg; Fluoranthene - 2230 ug/kg; Pyrene - 1520 ug/kg; PAH (total) - 22800 ug/kg; PCB (total) - 676 ug/kg; Chlordane - 17.6 ug/kg; Dieldrin - 61.8 ug/kg; DDD (sum op + pp) - 28 ug/kg; DDE (sum op + pp) - 31.3 ug/kg; DDT (sum op + pp) - 62.9 ug/kg; DDT (total) - 572 ug/kg; Endrin - 207 ug/kg; Heptachlor epoxide - 16 ug/kg; HCH, gamma - 4.99 ug/kg.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Baxter Creek.

Temporal Representation:

Sediment sample was collected in April of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	43820	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Arsenic \| Cadmium \| Copper \| Lead \| Mercury \| 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)(2012)
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 this section a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess these pollutants. Zero 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 one sample exceed the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 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.

Line of Evidence (LOE) for Decision ID 43820, Multiple Pollutants	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28637

Pollutant:

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentrations of arsenic, cadmium, copper, lead, mercury and zinc in one sediment sample collected in April 2005 did not exceed the sediment quality guidelines.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) arsenic - 33 mg/kg dw; cadmium - 4.98 mg/kg dw; chromium - 111 mg/kg dw; copper - 149 mg/kg dw; lead - 128 mg/kg dw; mercury - 1.06 mg/kg dw; nickel - 48.6 mg/kg dw; zinc - 459 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Baxter Creek.

Temporal Representation:

Sediment sample was collected in April of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	43053	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Arsenic \| Chromium (total) \| 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)(2012)
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 lines of evidence are available in the administrative record to assess these pollutants. 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. None of the three samples exceeded the water quality guideline 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.

Line of Evidence (LOE) for Decision ID 43053, Multiple Pollutants	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28839

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The Baxter Creek watershed was monitored as part of SWAMP assessment. None of the three samples exceeded the water quality objectives for arsenic, chromium VI, copper, lead, nickel, silver and zinc.
Concentrations of total dissolved chromium were well below the objective for chromium VI.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.
Table 3-4 in the Basin Plan (2007) lists freshwater water quality objectives for toxic pollutants: arsenic- 150 ug/L, chromium VI- 11 ug/L, 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:

Spatial Representation:

Data were collected at one sampling location (BAX030) on Baxter Creek (Baxter at Booker).

Temporal Representation:

Samples were collected during wet (January), spring (April), and dry( June) seasons of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	43821	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Chlordane
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)(2012)
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 this section 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. One sample exceeds 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 out of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 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.

Line of Evidence (LOE) for Decision ID 43821, Chlordane	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28773

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The sample exceeded the PEC (sediment quality guidelines) for chlordane at a concentration of 19.93 ug/kg in one sediment sample collected in spring 2005.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) Chlordane - 17.6 ug/kg.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Baxter Creek.

Temporal Representation:

Sediment sample was collected in April of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	44727	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Chlorpyrifos \| Dacthal \| Diazinon \| Disulfoton \| Endosulfan \| Lindane/gamma Hexachlorocyclohexane (gamma-HCH) \| Methyl Parathion \| PCBs (Polychlorinated biphenyls) \| Thiobencarb/Bolero
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)(2012)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	These pollutant 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 these pollutants. 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. None of the three samples exceeded the water quality objectives (Basin Plan) the Central Valley Water Quality Control Board Basin Plan 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.

Line of Evidence (LOE) for Decision ID 44727, Multiple Pollutants	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28956

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The Baxter Creek watershed was monitored as part of SWAMP assessment. None of the three samples exceeded the water quality objectives for PCBs, Chlorpyrifos, Dacthal, diazinon, disulfoton, endosulfan, Lindane/gamma Hexachlorocyclohexane (gamma-HCH), methyl parathion, thiobencarb.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.
There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community.
Diazinon water quality objective, 0.1 ug/L (acute)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

PCBs - 0.014 ug/L freshwater continuous Concentration; Chlorpyrifos - 0.015 ug/L (chronic); Dacthal (DCPA) - 14300 ug/L (acute); Disulfoton (Disyston) - 0.05 ug/L (acute); Endosulfan - 0.056 ug/L (chronic)/0.22 ug/L (acute); HCH, gamma-(gamma BHC, Lindane) - 0.95 ug/L (acute); methyl parathion - 0.08 ug/L (acute); Thiobencarb - 3.1 ug/L (acute).

Guideline Reference:

Spatial Representation:

Data were collected at one sampling location (BAX030) on Baxter Creek.

Temporal Representation:

Samples were collected during wet (January), spring (April), and dry( June) seasons of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	43822	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Chromium
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)(2012)
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 this section 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. One sample exceeds 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 out of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 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.

Line of Evidence (LOE) for Decision ID 43822, Chromium	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28755

Pollutant:

Chromium (total)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentration of chromium in one sediment sample collected in April 2005 exceeded the sediment quality guidelines. Chromium exceeded the PEC value with a sample concentration of 283 mg/kg dw.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) chromium - 111 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Baxter Creek.

Temporal Representation:

Sediment sample was collected in April of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	44205	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Escherichia coli (E. coli)
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)(2012)
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 3.2 of the Listing Policy. Under this section 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. One sample exceeds 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 out of one sample exceeds the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of five samples is needed for application of table 3.2. 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.

Line of Evidence (LOE) for Decision ID 44205, Escherichia coli (E. coli)	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28887

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Samples were collected as part of SWAMP sampling in the summer of 2004 at 7-day intervals and the geometric mean of the samples calculated over a five week interval. The geometric mean for this location was 1525 MNPN/100 mL.

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:

Uses of water for recreational activities involving body contact with water where ingestion of water is reasonably possible. These uses include, but are not limited to, swimming, wading, water-skiing, skin and scuba diving, surfing, whitewater activities, fishing, and uses of natural hot springs.

Water contact implies a risk of waterborne disease transmission and involves human health; accordingly, criteria required to protect this use are more stringent than those for more casual water-oriented recreation.
U.S. EPA water quality criteria for water contact recreation based on the frequency of use a particular area receives - 1986: the E. coli criterion is not to exceed 126 organisms/100 mL. The value is expressed as a 7-day geometric mean based on five or more samples per 30?day period; designated beach (max) 235 MPN/100 mL.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at BAX030 (Baxter at Booker).

Temporal Representation:

Samples were collected weekly from 7/20/2004 through 8/17/2004.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	44418	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Nickel
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)(2012)
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 this section 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. One sample exceeds 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 out of one sample exceeded the water quality objective, but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of two samples are needed for application of table 3.1. 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.

Line of Evidence (LOE) for Decision ID 44418, Nickel	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28756

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Concentration of Nickel in one sediment sample collected in April 2005 exceeded the sediment quality guidelines. Nickel exceeded the PEC value with a sample concentration of 247 mg/kg dw.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment Quality Guidelines (MacDonald et al., 2000): PEC (probable effect concentration) nickel - 48.6 mg/kg dw.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

One sediment sample was collected at a "watershed integrator" site located close to the mouth of Baxter Creek.

Temporal Representation:

Sediment sample was collected in April of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):


DECISION ID	43147	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Oxygen, Dissolved
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)(2012)
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 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Three 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. Three of six samples exceeded the water quality objectives (basin plan) 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.

Line of Evidence (LOE) for Decision ID 43147, Oxygen, Dissolved	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28560

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Comprehensive water quality assessment was conducted at Baxter Creek watershed as part of SWAMP assessment in 2004 and 2005. Continuous field monitoring of temperature, dissolved oxygen, pH, and specific conductance to determine temporal variability in basic water quality at one or two locations. The 7 day average minimum concentration of dissolved oxygen ranged from 1.2 to 15.6 mg/L and varied with season. Minimum dissolved oxygen levels fell below the objective of 5 mg/L once in each in March, July and September 2004. During that period minimum values of DO were 2.6, 3.4, and 3.7 mg/L, respectively.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The numeric water quality objective for dissolved oxygen is 5.0 mg/L minimum for waters designated as warm water habitat. The median dissolved oxygen concentration for any three consecutive months shall not be less than 80 percent of the dissolved oxygen content at saturation.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Dissolved oxygen was measured at one or two sites located on the mainstem of Baxter Creek that are representative of the entire creek length.

Temporal Representation:

At all locations the SWAMP performed continuous monitoring of dissolved oxygen at 15 minute intervals lasting 6-16 days during spring (March 2004), summer dry seasons (July and September 2004), and winter wet season (January 2005).

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 43147, Oxygen, Dissolved	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28715

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Comprehensive water quality assessment was conducted at Baxter Creek watershed as part of SWAMP assessment in 2004 and 2005. Continuous field monitoring of temperature, dissolved oxygen, pH, and specific conductance to determine temporal variability in basic water quality at one or two locations. The 7 day average minimum concentration of dissolved oxygen ranged from 2.6 to 10.9 mg/L and varied with season. Minimum dissolved oxygen levels fell below the objective of 7 mg/L once in each in March, July and September 2004. During that period average minimum values of DO were 2.6, 3.4, and 3.7 mg/L, respectively.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The numeric water quality objective for dissolved oxygen is 7.0 mg/L minimum for waters designated as cold water habitat. The median dissolved oxygen concentration for any three consecutive months shall not be less than 80 percent of the dissolved oxygen content at saturation.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Dissolved oxygen was measured at one or two locations, depending on the season, and located on the mainstem of Baxter Creek that are representative of the entire creek length.

Temporal Representation:

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):


DECISION ID	43148	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Temperature, water
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)(2012)
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 3.2 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. Two 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. Two of the six samples exceeded the An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria. Sustainable Ecosystems Institute, Portland, Oregon Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria. Sustainable Ecosystems Institute, Portland, Oregon (Sullivan K., Martin, D.J., Cardwell, R.D., Toll, J.E., Duke, S. 2000.) 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.

Line of Evidence (LOE) for Decision ID 43148, Temperature, water	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28343

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water quality assessment was conducted at the Baxter Creek watershed as part of SWAMP study in 2004-2005. Continuous field monitoring at 15 minute increments of temperature, dissolved oxygen, pH and specific conductance was conducted to determine temporal variability in basic water quality at three locations. Continuous monitoring sondes were deployed 6 times at 2 monitoring locations during wet, spring and dry seasons. The measured temperatures ranged from 10.3?C to 22.5 ?C and varied with season and location. During both dry season deployments at all 3 monitoring locations the 7-day mean temperature threshold for steelhead was exceeded. In total, the 17 ?C criterion was exceeded in 2 out of 6 deployments. .

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Temperature objectives for enclosed bays and estuaries are specified in the "Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays of California" including any revisions to the plan. In addition, the following temperature objectives apply to surface waters: The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5?F (2.8?C) above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sullivan et al. (2000) reviewed a wide range of studies incorporating information from laboratory-based research, field observations, and risk assessment approaches and developed criteria for assessing temperature risk to aquatic life. The 7-day mean temperature (maximum value of a 7-day moving average of the daily mean temperature) of 14.8?C was established as the upper threshold criterion for coho salmon and 17.0?C for steelhead trout. The risk assessment approach used by Sullivan et al. (2000) suggests that temperatures exceeding the above thresholds will cause a 10% reduction in average growth compared to optimal conditions.

Guideline Reference:

An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria

Spatial Representation:

Temperature was measured at three sites located on the mainstem of Baxter Creek that are representative of the entire creek length. The highest temperatures were recorded in July and September 2004.

Temporal Representation:

In 2004 and 2005 the SWAMP Program performed continuous monitoring of temperature at 15 minute intervals for periods of 1-2 weeks in each of three different seasons: summer (1 site), spring (2 sites), and fall (1 site).

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):


DECISION ID	43158	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	Toxicity
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)(2012)
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 the three samples exceeded the water quality guideline 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.

Line of Evidence (LOE) for Decision ID 43158, Toxicity	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28820

Pollutant:

Toxicity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Three samples were collected in 2005 to evaluate water toxicity at one monitoring location near the mouth of Baxter Creek. The toxicity tests included survival and reproduction of Ceriodaphnia, survival and growth of fathead minnow, and growth of Selenastrum. No toxicity was detected in three samples tested.

Data Reference:

Water Quality Monitoring and Bioassessment in Four San Francisco Bay Region Watersheds in 2003-2004: Kirker Creek, Mt. Diablo Creek, Petaluma River, and San Mateo Creek. Surface Water Monitoring Program, San Francisco Bay Regional Water Quality Control Board, Oakland. CA

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Water toxicity was evaluated according to the SWAMP methodology. The U.S.EPA whole effluent toxicity protocol (U.S.EPA 1994) was used to test the effect of water samples on three freshwater test organisms. Statistical evaluation (alpha = 0.05) and a default threshold of 80% of the control value were used to establish whether water exhibited significant toxicity adversely impacting aquatic organisms.

Guideline Reference:

Revised approach to toxicity test acceptability criteria using a statistical performance assessment. Environmental Toxicology and Chemistry, vol. 16, No. 6, pp 1322?1329

Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. EPA/600/4-91/002. Third Edition. July 1994

Spatial Representation:

Data were collected at one sampling location, BAX030, (Baxter at Booker) on three (3) occasions, representative of the lower reach of the creek.

Temporal Representation:

SWAMP samples were collected during winter wet season (January), spring season (April), and dry season (June) of 2005.

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 43158, Toxicity	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28866

Pollutant:

Sediment Toxicity

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Data used to evaluate sediment toxicity comprise one sediment sample collected by the SWAMP in spring 2005. This sample displayed statistically significant toxicity during the Hyalella azteca test. Hyalella azteca growth was only 53% of the control.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances that are lethal to or that produce other detrimental responses in aquatic organisms.

There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Sediment toxicity was evaluated according to the SWAMP methodology. Sample toxicity was determined by comparing mean organism response in samples and in negative controls. Statistical evaluation (alpha = 0.05) and a default threshold of 80% of the control value were used to establish whether the sediment exhibited significant toxicity adversely impacting aquatic organisms.

Guideline Reference:

Revised approach to toxicity test acceptability criteria using a statistical performance assessment. Environmental Toxicology and Chemistry, vol. 16, No. 6, pp 1322?1329

Spatial Representation:

Data were collected at one sampling location at the lower part of Baxter Creek.

Temporal Representation:

A sample was collected in spring season (April 2005).

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB, 2002).

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	43603	Region 2
Baxter Creek (Contra Costa County)

Pollutant:	pH
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)(2012)
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 3.2 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. Two 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. Two of the six samples exceeded the water quality objectives 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.

Line of Evidence (LOE) for Decision ID 43603, pH	Region 2
Baxter Creek (Contra Costa County)

LOE ID:

28545

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Comprehensive water quality assessment was conducted at Baxter Creek watershed as part of SWAMP assessment in 2004 and 2005. Continuous field monitoring of temperature, dissolved oxygen, pH, and specific conductance to determine temporal variability in basic water quality at one or two locations. The pH ranged from 7.0 to 8.6 and varied with season. The pH exceeded the maximum, (at 8.6) on two occasions, both at the lowest sampling location, in March 2004 and January 2005, respectively.

Data Reference:

Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

pH was measured at one or two sites located on the mainstem of Baxter Creek that are representative of the entire creek length.

Temporal Representation:

At all locations the SWAMP performed continuous monitoring of pH at 15 minute intervals lasting 6-16 days during spring (March 2004), summer dry seasons (July and September 2004), and winter wet season (January 2005).

Environmental Conditions:

QAPP Information:

All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002).

QAPP Information Reference(s):