| Water Body Name: | Sonoma Creek, non-tidal |
| Water Body ID: | CAR2064001020160627057356 |
| Water Body Type: | River & Stream |
DECISION ID |
87097 |
Region 2 |
Sonoma Creek, non-tidal |
||
| Pollutant: | Nutrients |
| Final Listing Decision: | 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 | Revised |
| Reason for Delisting: | Applicable WQS attained; reason for recovery unspecified |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for removal from the CWA section 303(d) List under section 4.11 of the Listing Policy. Under this section when all other delisting factors do not result in the delisting of a water segment but information indicates attainment of standards, a water segment shall be evaluated to determine whether the weight of evidence demonstrates that water quality standard is attained. If the weight of evidence indicates attainment, the water segment shall be removed from the CWA section 303(d) List.
The evaluation of eutrophic conditions requires the weight of evidence approach because the evaluation process examining a stream¿s trophic status requires measuring naturally occurring stream organisms (i.e., algae) and determining if the current amount of algae is affecting recreational beneficial uses or water quality parameters that influence aquatic life (e.g., pH and dissolved oxygen). Such an analysis requires the integration of secondary water quality indicators at sites with high algal biomass because the presence of algae alone does not demonstrate that aquatic impacts have occurred. The datasets used to evaluate nutrient impairment in the Creek are both spatially representative of the watershed and span a decade. Nutrient chemistry data were collected from 2002 (fall), 2003 (winter, summer), 2004 (spring), 2009 (summer), 2011 (late summer) 2012 (summer, late summer). The benthic algae-based lines of evidence were developed using data collected most recently in late summer of 2011 and 2012 and represent current conditions in the watershed. Therefore, this dataset meets the spatial and temporal Listing Policy requirements. We used two lines of evidence (i.e., benthic chlorophyll a, benthic percent macroalgae cover) to directly quantify the amount of algae in the stream, in order to determine if the narrative water quality objective for biostimulatory substances (i.e., eutrophication) is currently exceeded. Both metrics show a low proportion of exceedance, but there are not enough samples to use the binomial approach in Tables 4.1 or 4.2 of the Listing Policy. For the eutrophication-based lines of evidence (i.e., chlorophyll a and percent macroalgae cover) we collected 18 benthic chlorophyll a, 18 macroalgae percent cover. However, these measures are fairly consistent over time, so they take into account water quality conditions for weeks to months around the sample date. The temporally integrative nature of the algal biomass lines of evidence is supported by growth rates of algae, and the minor change in percent algae cover observed across the summer in 2012 at six sites. As a result, we are confident that the weight of evidence approach is appropriate for this analysis. For the four lines of evidence regarding nutrients with direct toxic effects (i.e., un-ionized ammonia, total ammonia, nitrite, and nitrate + nitrite), we used Listing Policy Table 4.1 criteria for toxicants to show that exceedances have been below the maximum number of exceedances allowed to remove a water segment and that municipal, agricultural, and aquatic life beneficial uses were not affected by nutrient toxicity. The nuisance algae indicators showed that the Creek is not impaired for nutrients because they had a low rate of exceedance of the applicable guidelines, and for those instances, the secondary indicators were not consistently exceeded. Of the samples collected in 2011 and 2012, we observed one (5.5 percent) exceedance for chlorophyll a based on the Cold Freshwater Habitat beneficial use threshold of 150 mg/m2, and no exceedances of the percent filamentous cover threshold of 30 percent. At the three sampling locations where we observed exceedances of these evaluation guidelines, the alternate algae indicator and secondary indicators (e.g., pH and dissolved oxygen) showed that potentially impacted beneficial uses were not affected by nutrients. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the CWA 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 following information indicates that the water quality standard is attained: 1 of 18 samples exceeded the evaluation guideline for benthic algae concentration. To use section 4.2, we would require a minimum of 26 samples so there is insufficient information to evaluate this line of evidence. Current conditions indicate that this evaluation guideline is exceeded a small proportion of the time despite not having 26 samples required for de-listing using binomial distribution requirements of the Listing Policy. 0 of 18 samples exceeded the evaluation guideline for percent cover of benthic algae. To use section 4.2, we would require a minimum of 26 samples so there is insufficient information to evaluate this line of evidence. Current conditions indicate that this evaluation guideline is exceeded a small proportion of the time despite not having 26 samples required for de-listing using binomial distribution requirements of the Listing Policy. 0 of 6 samples exceeded the evaluation guideline for un-ionized ammonia. To use section 4.2, we would require a minimum of 26 samples so there is insufficient information to evaluate this line of evidence. Current conditions indicate that this evaluation guideline is exceeded a small proportion of the time despite not having 26 samples required for de-listing using binomial distribution requirements of the Listing Policy. 0 of 86 samples exceeded the evaluation guideline for nitrogen as total ammonia. This number of exceedances meets the requirements for de-listing according to section 4.1 of the Listing Policy. 0 of 27 samples exceeded the evaluation guideline for pH. This number of exceedances meets the requirements for de-listing according to section 4.2 of the Listing Policy. |
| Regional Board Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be removed from the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded. |
|
|||||
| LOE ID: | 96643 | ||||
| Pollutant: | pH | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 27 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Numeric data generated from 27 minimums and maximums had 0 exceedances. | ||||
| Data Reference: | Staff Report to Support Delisting of Napa River and Sonoma Creek for Nutrients | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The San Francisco Bay Region Basin Plan states that: the pH shall not be depressed below 6.5 nor raised above 8.5. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | Samples were collected from the following 23 stations on Sonoma Creek and its tributaries: Nathanson Ck. @ Watmaugh just west of 5th Street, Nathanson Ck. @ Nathanson Park Napa Rd. to Larkin To Fine, Sonoma Ck. @ Maxwell Park near access from Riverside Drive, Sonoma Ck. near Sonoma Developmental Center, Sonoma Ck. @ Hwy 121, Schell Ck. @ Hwy 121, Carriger Ck. @ Marilyn Goode's property, Sonoma Ck. @ Agua Caliente, Sonoma Ck. @ Glen Allen (above confluence with Calabazas), Sonoma Ck. @ 986 Warm Springs Rd. 986 Warm Springs Road, Sonoma Ck. @ Goodspeed Bridge (above Bear Creek confluence), Sonoma Ck. @ Watmaugh, Calabazas Ck. @ Glen Allen (from Henno Road), Sonoma Ck. Sugarloaf State Park near Robert Ferguson Observatory, Rogers Ck. @ Arnold Drive, Carriger Ck. @ Watmaugh, Unnamed Ck. @ Lawndale Ave., Sonoma Ck. @ Mound Ave, Sonoma Ck. @ Hwy 12 near Hoff St, Sonoma Ck. @ Andrieux St., Sonoma Ck. @ Leveroni Rd., Nathanson Ck. @ 4th St., Sonoma Ck. @ Watmaugh | ||||
| Temporal Representation: | Samples were collected in August/September 2011, June 2012, and August/September 2012. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data. | ||||
| QAPP Information: | All data was collected following SWAMP Standard Operating Procedures and SWAMP Quality Assurance program Plan (QAPrP) (2008) and are considered SWAMP compliant. | ||||
| QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan | ||||
|
|||||
| LOE ID: | 96642 | ||||
| Pollutant: | Nitrogen, ammonia (Total Ammonia) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Total | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 86 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | The data consisted of 86 individual instantaneous ammonia samples collected during 2002, 2003, 2004, 2009, 2011, and 2012 compared to the criterion continuous concentration adjusted for the pH and temperature of the sample. When pH and temperature values were missing, the average pH and temperature values were used to compute the evaluation guideline. None of these samples exceeded the chronic criterion. | ||||
| Data Reference: | Staff Report to Support Delisting of Napa River and Sonoma Creek for Nutrients | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Surface waters shall not contain concentrations of chemical constituents in amounts that adversely affect any designated beneficial use. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Evaluation Guideline: | Water Quality Control Plan, San Francisco Bay Basin (RWQCB 2010): All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. There is no water quality objective for ammonia in the Water Quality Control Plan, San Francisco Bay Basin. Instead, the 2013 U.S. EPA criteria for ammonia was used as Temperature and pH-Dependent Values of the CCC (Chronic Criterion)for Fish Early Life Stages Present. For the pH and temperatures in this data set, the chronic criterion ranged from 0.1-2.8 mg/L and averaged 0.769 mg/L total ammonia. | ||||
| Guideline Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 | |||||
| Spatial Representation: | Samples were collected from the following 23 stations on Sonoma Creek and its tributaries: Nathanson Ck. @ Watmaugh just west of 5th Street, Nathanson Ck. @ Nathanson Park Napa Rd. to Larkin To Fine, Sonoma Ck. @ Maxwell Park near access from Riverside Drive, Sonoma Ck. near Sonoma Developmental Center, Sonoma Ck. @ Hwy 121, Schell Ck. @ Hwy 121, Carriger Ck. @ Marilyn Goode's property, Sonoma Ck. @ Agua Caliente, Sonoma Ck. @ Glen Allen (above confluence with Calabazas), Sonoma Ck. @ 986 Warm Springs Rd. 986 Warm Springs Road, Sonoma Ck. @ Goodspeed Bridge (above Bear Creek confluence), Sonoma Ck. @ Watmaugh, Calabazas Ck. @ Glen Allen (from Henno Road), Sonoma Ck. Sugarloaf State Park near Robert Ferguson Observatory, Rogers Ck. @ Arnold Drive, Carriger Ck. @ Watmaugh, Unnamed Ck. @ Lawndale Ave., Sonoma Ck. @ Mound Ave, Sonoma Ck. @ Hwy 12 near Hoff St, Sonoma Ck. @ Andrieux St., Sonoma Ck. @ Leveroni Rd., Nathanson Ck. @ 4th St., Sonoma Ck. @ Watmaugh | ||||
| Temporal Representation: | Samples were collected during 2002, 2003, 2004, 2009, 2011, and 2012. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data. | ||||
| QAPP Information: | Some data were collected by Water Board staff following SWAMP Standard Operating Procedures and SWAMP Quality Assurance program Plan (QAPrP) (2008) and are SWAMP compliant, other data were collected by the San Francisco Estuary Institute. | ||||
| QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan | ||||
|
|||||
| LOE ID: | 94536 | ||||
| Pollutant: | Nutrients | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Not Recorded | ||||
| Beneficial Use: | Warm 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): | |||||
|
|||||
| LOE ID: | 96640 | ||||
| Pollutant: | Algae | ||||
| LOE Subgroup: | Pollutant-Nuisance | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 18 | ||||
| Number of Exceedances: | 0 | ||||
| Data and Information Type: | Occurrence of conditions judged to cause impairment | ||||
| Data Used to Assess Water Quality: | The percent cover data were collected according to the SWAMP Standard Operating Procedures for Collecting Stream Algae Samples and Associated Physical Habitat and Chemical Data for Ambient Bioassessments in California (Fetscher et al. 2009). According to this method, the presence of attached or un-attached macroalgae is observed at 105 systematic points along the stream reach. The number of observed points with either attached or un-attached macroalgae out of the 105 inspected points is used to determine the percent macroalgae cover for the 150m section of stream. None of the 18 samples exceeded the evaluation guideline for percent macroalgae cover. | ||||
| Data Reference: | DRAFT SWAMP Reachwide Benthos Method for Stream Algae Sampling and Associated Physical Habitat Data Collection. Version 6 | ||||
| Staff Report to Support Delisting of Napa River and Sonoma Creek for Nutrients | |||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The Water Quality Control Plan for the San Francisco Bay Basin states that waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Evaluation Guideline: | Biggs (2000) recommends a 30 percent cover by filamentous green or brown algae as a threshold associated with benthic chlorophyll-a levels consistent with protection of recreation and fisheries. | ||||
| Guideline Reference: | New Zealand Periphyton Guideline: Detecting Monitoring and Managing Enrichment of Streams | ||||
| Spatial Representation: | Percent algae cover were collected from the following 9 stations on Sonoma Creek:Sonoma Ck. @ Maxwell Park near access from Riverside Drive, Sonoma Ck. near Sonoma Developmental Center, Sonoma Ck. @ Glen Allen (above confluence with Calabazas), Sonoma Ck. @ 986 Warm Springs Rd. 986 Warm Springs Road, Sonoma Ck. @ Goodspeed Bridge (above Bear Creek confluence), Sonoma Ck. Sugarloaf State Park near Robert Ferguson Observatory, Unnamed Ck. @ Lawndale Ave., Sonoma Ck. @ Hwy 12 near Hoff St, Sonoma Ck. @ Watmaugh | ||||
| Temporal Representation: | Samples were collected in August/September 2011, and August/September 2012. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data. | ||||
| QAPP Information: | All data was collected following SWAMP Standard Operating Procedures and SWAMP Quality Assurance program Plan (QAPrP) (2008) and are considered SWAMP compliant. | ||||
| QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan | ||||
|
|||||
| LOE ID: | 96639 | ||||
| Pollutant: | Algae | ||||
| LOE Subgroup: | Pollutant-Nuisance | ||||
| Matrix: | -N/A | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 18 | ||||
| Number of Exceedances: | 1 | ||||
| Data and Information Type: | Occurrence of conditions judged to cause impairment | ||||
| Data Used to Assess Water Quality: | The data consist of benthic chlorophyll-a samples collected according to the SWAMP bioassessment protocol (Fetscher et al. 2009). One of the 18 benthic chlorophyll-a samples exceeded the evaluation guideline. | ||||
| Data Reference: | DRAFT SWAMP Reachwide Benthos Method for Stream Algae Sampling and Associated Physical Habitat Data Collection. Version 6 | ||||
| Staff Report to Support Delisting of Napa River and Sonoma Creek for Nutrients | |||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | The Water Quality Control Plan for the San Francisco Bay Basin states that waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect beneficial uses. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Evaluation Guideline: | The Technical Approach to Develop Nutrient Numeric Endpoints for California. (Tetra Tech 2006) suggests that concentrations of benthic algae above 150 mg/m2 are presumed to be impaired for Cold Freshwater Habitat. This concentration represents the threshold above which the risk of beneficial use impairment by nutrients is probable. | ||||
| Guideline Reference: | Technical Approach to Develop Nutrient Numeric Endpoints for California | ||||
| Spatial Representation: | Benthic chlorophyll-a data were collected from the following 9 stations on Sonoma Creek: Sonoma Ck. @ Maxwell Park near access from Riverside Drive, Sonoma Ck. near Sonoma Developmental Center, Sonoma Ck. @ Glen Allen (above confluence with Calabazas), Sonoma Ck. @ 986 Warm Springs Rd. 986 Warm Springs Road, Sonoma Ck. @ Goodspeed Bridge (above Bear Creek confluence), Sonoma Ck. Sugarloaf State Park near Robert Ferguson Observatory, Unnamed Ck. @ Lawndale Ave., Sonoma Ck. @ Hwy 12 near Hoff St, Sonoma Ck. @ Watmaugh | ||||
| Temporal Representation: | Samples were collected in August/September 2011, June 2012, and August/September 2012. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data. | ||||
| QAPP Information: | All data was collected following SWAMP Standard Operating Procedures and SWAMP Quality Assurance program Plan (QAPrP) (2008) and are considered SWAMP compliant. | ||||
| QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan | ||||
|
|||||
| LOE ID: | 96641 | ||||
| Pollutant: | Ammonia (Unionized) | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | Dissolved | ||||
| 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: | Annual medians computed from 86 samples collected during 2002, 2003, 2004, 2009, 2011, and 2012. None of the six annual medians exceeded the objective. | ||||
| Data Reference: | Staff Report to Support Delisting of Napa River and Sonoma Creek for Nutrients | ||||
| SWAMP Data: | SWAMP | ||||
| Water Quality Objective/Criterion: | Water Quality Control Plan, San Francisco Bay Basin General Objective, Chapter III, Section 3.3.20. The discharge of wastes shall not cause receiving waters to contain annual median concentrations of un-ionized ammonia in excess 0.025 mg/l as N. | ||||
| Objective/Criterion Reference: | Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2) | ||||
| Evaluation Guideline: | |||||
| Guideline Reference: | |||||
| Spatial Representation: | Samples were collected from the following 23 stations on Sonoma Creek and its tributaries: Nathanson Ck. @ Watmaugh just west of 5th Street, Nathanson Ck. @ Nathanson Park Napa Rd. to Larkin To Fine, Sonoma Ck. @ Maxwell Park near access from Riverside Drive, Sonoma Ck. near Sonoma Developmental Center, Sonoma Ck. @ Hwy 121, Schell Ck. @ Hwy 121, Carriger Ck. @ Marilyn Goode's property, Sonoma Ck. @ Agua Caliente, Sonoma Ck. @ Glen Allen (above confluence with Calabazas), Sonoma Ck. @ 986 Warm Springs Rd. 986 Warm Springs Road, Sonoma Ck. @ Goodspeed Bridge (above Bear Creek confluence), Sonoma Ck. @ Watmaugh, Calabazas Ck. @ Glen Allen (from Henno Road), Sonoma Ck. Sugarloaf State Park near Robert Ferguson Observatory, Rogers Ck. @ Arnold Drive, Carriger Ck. @ Watmaugh, Unnamed Ck. @ Lawndale Ave., Sonoma Ck. @ Mound Ave, Sonoma Ck. @ Hwy 12 near Hoff St, Sonoma Ck. @ Andrieux St., Sonoma Ck. @ Leveroni Rd., Nathanson Ck. @ 4th St., Sonoma Ck. @ Watmaugh | ||||
| Temporal Representation: | Samples were collected during 2002, 2003, 2004, 2009, 2011, and 2012. | ||||
| Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data. | ||||
| QAPP Information: | Some data were collected by Water Board staff following SWAMP Standard Operating Procedures and SWAMP Quality Assurance program Plan (QAPrP) (2008) and are SWAMP compliant, other data were collected by the San Francisco Estuary Institute. | ||||
| QAPP Information Reference(s): | Surface Water Ambient Monitoring Program Quality Assurance Program Plan | ||||