| Water Body Name: | Los Gatos Creek, Lower |
| Water Body ID: | CAR2054005020171207059470 |
| Water Body Type: | River & Stream |
DECISION ID |
100663 |
Region 2 |
Los Gatos Creek, Lower |
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| Pollutant: | Temperature, water |
| Final Listing Decision: | List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | New Decision |
| Revision Status | Revised |
| Sources: | Source Unknown |
| Expected TMDL Completion Date: | 2031 |
| Impairment from Pollutant or Pollution: | Pollutant |
| Regional Board Conclusion: | This pollutant is being considered for placement on the CWA 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.
Four lines of evidence are available in the administrative record to assess this pollutant. Rolling 7-day average temperatures were computed for the hourly temperature monitoring data for the period March through October. 30499 of 47179 samples exceed the evaluation guideline for 7-day average temperature. Rolling 7-day averages of maximum daily temperature were also computed. 3053 of 16427 samples exceed the evaluation guideline for 7-day average of daily maximum temperature. We also examined the Maximum Weekly Average Temperature (MWAT) for March through October for all years of data. 229 of 261 samples exceeded the evaluation guideline for this temperature threshold. We also examined the proportion of days in which the temperature reached an acute threshold for salmonids (24 degrees C).6726 of 48857 samples exceed the evaluation guideline for the acute temperature threshold. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on 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 data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 30499 of 47179 samples (65%) exceed the evaluation guideline for 7-day average temperature and this exceeds 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: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem. |
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| LOE ID: | 96651 | ||||
| Pollutant: | Temperature, water | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 47179 | ||||
| Number of Exceedances: | 30499 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were used in the evaluation.
The 7-day moving average temperatures were computed for the contiguous 7-day periods available during this time frame. The 7-day average temperature exceeded the evaluation guideline during 30499 of these 47179 7-day periods (65% exceedance). Data were collected at the following locations: 30200-1 Lincoln Ave. at Gauge SF50 37.312586 -121.904335, 30200-2 u/s RR Trestle d/s Lincoln Ave. 37.314586 -121.903679, 30200-3 Lincoln Ave Outfall Outfall downstream of Lincoln Ave. 37.313662 -121.90384, 30200-4 d/s Meridian Ave. 37.307198 -121.913038, 30200-5 Upstream of Confluence w/ Guad River 37.333812 -121.899001, 30200-6 West San Fernando St. 37.329356 -121.899478, 30200-7 Auzerais Street 37.321246 -121.902768, 30200-8 Lonus Street, d/s SPRR trestle 37.315715 -121.90327, 30200-9 Glen Eyrie @ Carolyn. 37.310046 -121.907277, 30200-10 Stokes between Leigh and Meridian. 37.30399 -121.916547, 30200-11 Bascom/Leigh @ De Loach Ct. 37.298779 -121.927042, 30200-12 U/S Bascom Avenue. 37.296828 -121.932682, 30200-13 U/S CPL Outlet 37.28993777 -121.9369153, 30200-14 Upstream of Campbell Park 37.283826 -121.940952, 30200-15 @ Timber Cove Mobile Home Park 37.275955 -121.947087, 30200-16 D/S Camden Drop Structure 37.272772 -121.948101, 30200-17 Middle Page Impoundment Inlet 37.269299 -121.949122, 30200-18 D/s Vasona Valve Yard 37.258782 -121.960141, 30200-19 D/s Lark at JCC 37.253114 -121.963321, 30200-20 Downstream of Vasona Reservoir. 37.247413 -121.96527, 30200-21 Los Gatos Creek at Vasona Inlet 37.23718558 -121.9740122, 30200-23 Downstream of Hwy 9 37.227853 -121.97628, 30200-24 Main Street Upstream 37.221381 -121.982444, 30200-25 Upstream of Oak Grove Ct. 37.215124 -121.987373, 30200-26 Los Gatos Creek u/s of Alma Presentation 37.20856592 -121.9888063, 30200-27 d/s Lexington Outlet 37.205646 -121.989567, 30200-31 Vasona Inlet 37.23847639 -121.972282, 30200-33 d/s Middle Page Drop Structure (Page Dam #2) 37.27068668 -121.9490734, 30200-34 U/S Campbell Ave. at LGCT Pedestrian bridge 37.28596348 -121.9386781, 30200-35 d/s Hwy 17 (d/s CPL Outlet) 37.29017516 -121.9368202, 30200-36 Vasona Reservoir Inlet 37.23473507 -121.9736032, 30200-38 Upstream of confluence with Guadalupe River 37.33168754 -121.8995946 |
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| Data Reference: | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
| Temperature data (2000-2012) and associated documents from Los Gatos Creek. | |||||
| SWAMP Data: | Non-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 Basin (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)suggest that temperatures exceeding the above thresholds will cause a 10% reduction in average growth compared to optimal conditions. We applied the 17.0°C for steelhead trout evaluation guideline during months of March through October. | ||||
| Guideline Reference: | An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria | ||||
| Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region | |||||
| Spatial Representation: | Data were collected from 32 monitoring locations along the length of lower Los Gatos Creek. | ||||
| Temporal Representation: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were used to assess data in comparison to this evaluation guideline. | ||||
| Environmental Conditions: | These data were collected hourly and thus represent the full range of environmental conditions present in this creek. | ||||
| QAPP Information: | The data were collected by the Santa Clara Valley Water District and are deemed to be reliable and of sound quality. Information about the monitoring equipment used is available in the reference (Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012). | ||||
| QAPP Information Reference(s): | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
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| LOE ID: | 96750 | ||||
| Pollutant: | Temperature, water | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 261 | ||||
| Number of Exceedances: | 229 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were used in the evaluation.
We computed the maximum of the 7-day moving average temperatures during this March to October time frame for each station and year combination. The MWAT exceeded the evaluation guideline during 229 of these 261 deployments (88% exceedance). The 7-day moving average temperatures were computed for the contiguous 7-day periods available during this time frame. The 7-day average temperature exceeded the evaluation guideline during 30499 of these 47179 7-day periods (65% exceedance). Data were collected at the following locations: 30200-1 Lincoln Ave. at Gauge SF50 37.312586 -121.904335, 30200-2 u/s RR Trestle d/s Lincoln Ave. 37.314586 -121.903679, 30200-3 Lincoln Ave Outfall Outfall downstream of Lincoln Ave. 37.313662 -121.90384, 30200-4 d/s Meridian Ave. 37.307198 -121.913038, 30200-5 Upstream of Confluence w/ Guad River 37.333812 -121.899001, 30200-6 West San Fernando St. 37.329356 -121.899478, 30200-7 Auzerais Street 37.321246 -121.902768, 30200-8 Lonus Street, d/s SPRR trestle 37.315715 -121.90327, 30200-9 Glen Eyrie @ Carolyn. 37.310046 -121.907277, 30200-10 Stokes between Leigh and Meridian. 37.30399 -121.916547, 30200-11 Bascom/Leigh @ De Loach Ct. 37.298779 -121.927042, 30200-12 U/S Bascom Avenue. 37.296828 -121.932682, 30200-13 U/S CPL Outlet 37.28993777 -121.9369153, 30200-14 Upstream of Campbell Park 37.283826 -121.940952, 30200-15 @ Timber Cove Mobile Home Park 37.275955 -121.947087, 30200-16 D/S Camden Drop Structure 37.272772 -121.948101, 30200-17 Middle Page Impoundment Inlet 37.269299 -121.949122, 30200-18 D/s Vasona Valve Yard 37.258782 -121.960141, 30200-19 D/s Lark at JCC 37.253114 -121.963321, 30200-20 Downstream of Vasona Reservoir. 37.247413 -121.96527, 30200-21 Los Gatos Creek at Vasona Inlet 37.23718558 -121.9740122, 30200-23 Downstream of Hwy 9 37.227853 -121.97628, 30200-24 Main Street Upstream 37.221381 -121.982444, 30200-25 Upstream of Oak Grove Ct. 37.215124 -121.987373, 30200-26 Los Gatos Creek u/s of Alma Presentation 37.20856592 -121.9888063, 30200-27 d/s Lexington Outlet 37.205646 -121.989567, 30200-31 Vasona Inlet 37.23847639 -121.972282, 30200-33 d/s Middle Page Drop Structure (Page Dam #2) 37.27068668 -121.9490734, 30200-34 U/S Campbell Ave. at LGCT Pedestrian bridge 37.28596348 -121.9386781, 30200-35 d/s Hwy 17 (d/s CPL Outlet) 37.29017516 -121.9368202, 30200-36 Vasona Reservoir Inlet 37.23473507 -121.9736032, 30200-38 Upstream of confluence with Guadalupe River 37.33168754 -121.8995946 |
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| Data Reference: | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
| Temperature data (2000-2012) and associated documents from Los Gatos Creek. | |||||
| SWAMP Data: | Non-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 Basin (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 Updated EPA method for the 7-day mean temperature (maximum value of a 7-day moving average of the daily mean temperature, MWAT) of 19.6°C was established as the upper threshold criterion for steelhead trout. We applied the 19.6°C for steelhead trout as an evaluation guideline during months of March through October. | ||||
| Guideline Reference: | An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria | ||||
| Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region | |||||
| Spatial Representation: | Data were collected from 32 monitoring locations along the length of lower Los Gatos Creek. | ||||
| Temporal Representation: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were used to assess data in comparison to this evaluation guideline. | ||||
| Environmental Conditions: | These data were collected hourly and thus represent the full range of environmental conditions present in this creek. | ||||
| QAPP Information: | The data were collected by the Santa Clara Valley Water District and are deemed to be reliable and of sound quality. Information about the monitoring equipment used is available in the reference (Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012). | ||||
| QAPP Information Reference(s): | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
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| LOE ID: | 96649 | ||||
| Pollutant: | Temperature, water | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Cold Freshwater Habitat | ||||
| Number of Samples: | 48857 | ||||
| Number of Exceedances: | 6726 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were evaluated for this metric.
The temperature exceeded the evaluation guideline on 6726 of 48857 days (14% exceedance). Data were collected at the following locations: 30200-1 Lincoln Ave. at Gauge SF50 37.312586 -121.904335, 30200-2 u/s RR Trestle d/s Lincoln Ave. 37.314586 -121.903679, 30200-3 Lincoln Ave Outfall Outfall downstream of Lincoln Ave. 37.313662 -121.90384, 30200-4 d/s Meridian Ave. 37.307198 -121.913038, 30200-5 Upstream of Confluence w/ Guad River 37.333812 -121.899001, 30200-6 West San Fernando St. 37.329356 -121.899478, 30200-7 Auzerais Street 37.321246 -121.902768, 30200-8 Lonus Street, d/s SPRR trestle 37.315715 -121.90327, 30200-9 Glen Eyrie @ Carolyn. 37.310046 -121.907277, 30200-10 Stokes between Leigh and Meridian. 37.30399 -121.916547, 30200-11 Bascom/Leigh @ De Loach Ct. 37.298779 -121.927042, 30200-12 U/S Bascom Avenue. 37.296828 -121.932682, 30200-13 U/S CPL Outlet 37.28993777 -121.9369153, 30200-14 Upstream of Campbell Park 37.283826 -121.940952, 30200-15 @ Timber Cove Mobile Home Park 37.275955 -121.947087, 30200-16 D/S Camden Drop Structure 37.272772 -121.948101, 30200-17 Middle Page Impoundment Inlet 37.269299 -121.949122, 30200-18 D/s Vasona Valve Yard 37.258782 -121.960141, 30200-19 D/s Lark at JCC 37.253114 -121.963321, 30200-20 Downstream of Vasona Reservoir. 37.247413 -121.96527, 30200-21 Los Gatos Creek at Vasona Inlet 37.23718558 -121.9740122, 30200-23 Downstream of Hwy 9 37.227853 -121.97628, 30200-24 Main Street Upstream 37.221381 -121.982444, 30200-25 Upstream of Oak Grove Ct. 37.215124 -121.987373, 30200-26 Los Gatos Creek u/s of Alma Presentation 37.20856592 -121.9888063, 30200-27 d/s Lexington Outlet 37.205646 -121.989567, 30200-31 Vasona Inlet 37.23847639 -121.972282, 30200-33 d/s Middle Page Drop Structure (Page Dam #2) 37.27068668 -121.9490734, 30200-34 U/S Campbell Ave. at LGCT Pedestrian bridge 37.28596348 -121.9386781, 30200-35 d/s Hwy 17 (d/s CPL Outlet) 37.29017516 -121.9368202, 30200-36 Vasona Reservoir Inlet 37.23473507 -121.9736032, 30200-38 Upstream of confluence with Guadalupe River 37.33168754 -121.8995946 |
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| Data Reference: | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
| Temperature data (2000-2012) and associated documents from Los Gatos Creek. | |||||
| SWAMP Data: | Non-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 Basin (Region 2) | ||||
| Evaluation Guideline: | Per "Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids" (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C. | ||||
| Guideline Reference: | Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C | ||||
| Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region | |||||
| Inland Fishes of California | |||||
| Spatial Representation: | Data were collected from 32 monitoring locations along lower Los Gatos Creek. | ||||
| Temporal Representation: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. March through October data were used to assess data in comparison to this evaluation guideline. | ||||
| Environmental Conditions: | These data were collected hourly and thus represent the full range of environmental conditions present in this creek. | ||||
| QAPP Information: | The data were collected by the Santa Clara Valley Water District and are deemed to be reliable and of sound quality. Information about the monitoring equipment used is available in the reference (Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012). | ||||
| QAPP Information Reference(s): | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
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| LOE ID: | 96647 | ||||
| Pollutant: | Temperature, water | ||||
| LOE Subgroup: | Pollutant-Water | ||||
| Matrix: | Water | ||||
| Fraction: | None | ||||
| Beneficial Use: | Fish Migration | ||||
| Number of Samples: | 16427 | ||||
| Number of Exceedances: | 3053 | ||||
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING | ||||
| Data Used to Assess Water Quality: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. Data from out-migration period - March 1 through June 15 (Shapovalov and Taft 1954) were assessed.
The 7-day moving average of maximum daily temperatures were computed for the contiguous 7-day periods available during this time frame. The 7-day average of maximum daily temperature exceeded the evaluation guideline during 3053 of these 16427 7-day periods (18.5% exceedance). Data were collected at the following locations: 30200-1 Lincoln Ave. at Gauge SF50 37.312586 -121.904335, 30200-2 u/s RR Trestle d/s Lincoln Ave. 37.314586 -121.903679, 30200-3 Lincoln Ave Outfall Outfall downstream of Lincoln Ave. 37.313662 -121.90384, 30200-4 d/s Meridian Ave. 37.307198 -121.913038, 30200-5 Upstream of Confluence w/ Guad River 37.333812 -121.899001, 30200-6 West San Fernando St. 37.329356 -121.899478, 30200-7 Auzerais Street 37.321246 -121.902768, 30200-8 Lonus Street, d/s SPRR trestle 37.315715 -121.90327, 30200-9 Glen Eyrie @ Carolyn. 37.310046 -121.907277, 30200-10 Stokes between Leigh and Meridian. 37.30399 -121.916547, 30200-11 Bascom/Leigh @ De Loach Ct. 37.298779 -121.927042, 30200-12 U/S Bascom Avenue. 37.296828 -121.932682, 30200-13 U/S CPL Outlet 37.28993777 -121.9369153, 30200-14 Upstream of Campbell Park 37.283826 -121.940952, 30200-15 @ Timber Cove Mobile Home Park 37.275955 -121.947087, 30200-16 D/S Camden Drop Structure 37.272772 -121.948101, 30200-17 Middle Page Impoundment Inlet 37.269299 -121.949122, 30200-18 D/s Vasona Valve Yard 37.258782 -121.960141, 30200-19 D/s Lark at JCC 37.253114 -121.963321, 30200-20 Downstream of Vasona Reservoir. 37.247413 -121.96527, 30200-21 Los Gatos Creek at Vasona Inlet 37.23718558 -121.9740122, 30200-23 Downstream of Hwy 9 37.227853 -121.97628, 30200-24 Main Street Upstream 37.221381 -121.982444, 30200-25 Upstream of Oak Grove Ct. 37.215124 -121.987373, 30200-26 Los Gatos Creek u/s of Alma Presentation 37.20856592 -121.9888063, 30200-27 d/s Lexington Outlet 37.205646 -121.989567, 30200-31 Vasona Inlet 37.23847639 -121.972282, 30200-33 d/s Middle Page Drop Structure (Page Dam #2) 37.27068668 -121.9490734, 30200-34 U/S Campbell Ave. at LGCT Pedestrian bridge 37.28596348 -121.9386781, 30200-35 d/s Hwy 17 (d/s CPL Outlet) 37.29017516 -121.9368202, 30200-36 Vasona Reservoir Inlet 37.23473507 -121.9736032, 30200-38 Upstream of confluence with Guadalupe River 37.33168754 -121.8995946 |
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| Data Reference: | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||
| Temperature data (2000-2012) and associated documents from Los Gatos Creek. | |||||
| SWAMP Data: | Non-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 Basin (Region 2) | ||||
| Evaluation Guideline: | A 7-DADM (7 day average of daily maximum) temperature of 20ºC is recommended by the USEPA (2003) for waterbodies that are used almost exclusively for migration during the period of summer maximum temperatures (we used the out-migration period of March 1 through June 15 from Shapovalov and Taft 1954). EPA believes that a 20ºC criterion would protect migrating juveniles and adults from lethal temperatures and would prevent migration blockage conditions.
However, EPA is concerned that rivers with significant hydrologic alterations (e.g., rivers with dams and reservoirs, water withdrawals, and /or significant river channelization) may experience a loss of temperature diversity in the river, such that maximum temperatures occur for an extended period of time and there is little cold water refugia available for fish to escape maximum temperatures. In this case, even if the river meets a 20ºC criterion for maximum temperatures, the duration of exposure to 20ºC temperatures may cause adverse effects in the form of increased disease and decreased swimming performance in adults, and increased disease, impaired smoltification, reduced growth, and increased predation for late emigrating juveniles |
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| Guideline Reference: | The Life Histories of The Steelhead Rainbow Trout (Salmo Gairderi Gairdneri) and Silver Salmon (Oncorhynchus Kisutch) With Special Reference To Waddell Creek CA and Recommendations Regarding Their Management | ||||
| EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. U.S. Environmental Protection Agency Region 10 Office of Water, Seattle, WA. | |||||
| Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region | |||||
| Spatial Representation: | Data were collected from 32 monitoring locations along lower Los Gatos Creek. | ||||
| Temporal Representation: | Data collected hourly from 2000 through 2012 at 32 monitoring stations along lower Los Gatos Creek by the Santa Clara Valley Water District. Data from out-migration period - March 1 through June 15 - were assessed for this metric. | ||||
| Environmental Conditions: | These data were collected hourly and thus represent the full range of environmental conditions present in this creek. | ||||
| QAPP Information: | The data were collected by the Santa Clara Valley Water District and are deemed to be reliable and of sound quality. Information about the monitoring equipment used is available in the reference (Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012). | ||||
| QAPP Information Reference(s): | Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012. | ||||