Final California 2018 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Los Gatos Creek, Upper
Water Body ID:	CAR2054001020171207059323
Water Body Type:	River & Stream


DECISION ID	100664	Region 2
Los Gatos Creek, Upper

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
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. 887 of 5444 samples exceed the evaluation guideline for 7-day average temperature. Rolling 7-day averages of maximum daily temperature were also computed. Zero of 1867 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. Four of 37 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). Zero of 5687 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 against 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. 887 of 5444 samples (16%) exceed the evaluation guideline for 7-day average temperature 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:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 100664, Temperature, water	Region 2
Los Gatos Creek, Upper

LOE ID:

96650

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Fish Migration

Number of Samples:

1867

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek by the Santa Clara Valley Water District. Data from out-migration period (March 1 through June 15 from Shapovalov and Taft 1954) were assessed.

The 7-day moving average of maximum daily temperatures were computed for all contiguous 7-day periods available during this time frame. The 7-day average of maximum daily temperature exceeded the evaluation guideline during none of these 1867 7-day periods (0% exceedance).

Data were collected at the following locations:
30200-28 Ryland Diversion Dam, d/s 37.1647355 -121.9783592,
30200-29 Hooker Gulch Creek Confluence-d/s 37.15376232 -121.9641413,
30200-30 Hooker Gulch Creek Confluence-u/s 37.15421103 -121.9634054,
30200-32 Lexington Inlet @ Alma Road Bridge 37.16832195 -121.9810351,
30200-37 Wright's Station Road 37.13822178 -121.9473038,

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 outmigration 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

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 5 monitoring locations along the reach of upper Los Gatos Creek (above Lexington Reservoir).

Temporal Representation:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek (above Lexington Reservoir) by the Santa Clara Valley Water District. Data from out-migration period - March 1 through June 15 were assessed.

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.

Line of Evidence (LOE) for Decision ID 100664, Temperature, water	Region 2
Los Gatos Creek, Upper

LOE ID:

96648

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

5444

Number of Exceedances:

887

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek by the Santa Clara Valley Water District. We investigated data in the range of March through October for this metric.

The 7-day moving average temperatures were computed for all available contiguous 7-day periods available during this March to October time frame. The 7-day average temperature exceeded the evaluation guideline during 887 of these 5444 7-day periods (16% exceedance).

Data were collected at the following locations:
30200-28 Ryland Diversion Dam, d/s 37.1647355 -121.9783592,
30200-29 Hooker Gulch Creek Confluence-d/s 37.15376232 -121.9641413,
30200-30 Hooker Gulch Creek Confluence-u/s 37.15421103 -121.9634054,
30200-32 Lexington Inlet @ Alma Road Bridge 37.16832195 -121.9810351,
30200-37 Wright's Station Road 37.13822178 -121.9473038,

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:

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 Summer 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

Spatial Representation:

Data were collected from 5 monitoring locations along the reach of upper Los Gatos Creek (above Lexington Reservoir).

Temporal Representation:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek (above Lexington Reservoir) 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:

QAPP Information Reference(s):

Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012.

Line of Evidence (LOE) for Decision ID 100664, Temperature, water	Region 2
Los Gatos Creek, Upper

LOE ID:

96652

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

5687

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek by the Santa Clara Valley Water District. March through October data were assessed.

The temperature exceeded the evaluation guideline on 0 of 5687 days (0% exceedance).

Data were collected at the following locations:
30200-28 Ryland Diversion Dam, d/s 37.1647355 -121.9783592,
30200-29 Hooker Gulch Creek Confluence-d/s 37.15376232 -121.9641413,
30200-30 Hooker Gulch Creek Confluence-u/s 37.15421103 -121.9634054,
30200-32 Lexington Inlet @ Alma Road Bridge 37.16832195 -121.9810351,
30200-37 Wright's Station Road 37.13822178 -121.9473038,

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:

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

Inland Fishes of California

Spatial Representation:

Data were collected from 5 monitoring locations along the reach of upper Los Gatos Creek (above Lexington Reservoir).

Temporal Representation:

Environmental Conditions:

These data were collected hourly and thus represent the full range of environmental conditions present in this creek.

QAPP Information:

QAPP Information Reference(s):

Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012.

Line of Evidence (LOE) for Decision ID 100664, Temperature, water	Region 2
Los Gatos Creek, Upper

LOE ID:

96749

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:

Data collected hourly from 2000 through 2012 at 5 monitoring stations along upper Los Gatos Creek by the Santa Clara Valley Water District. We investigated data in the range of March through October for this metric.

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 4 of these 37 deployments (11% exceedance).

Data were collected at the following locations:
30200-28 Ryland Diversion Dam, d/s 37.1647355 -121.9783592,
30200-29 Hooker Gulch Creek Confluence-d/s 37.15376232 -121.9641413,
30200-30 Hooker Gulch Creek Confluence-u/s 37.15421103 -121.9634054,
30200-32 Lexington Inlet @ Alma Road Bridge 37.16832195 -121.9810351,
30200-37 Wright's Station Road 37.13822178 -121.9473038,

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:

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

Spatial Representation:

Data were collected from 5 monitoring locations along the reach of upper Los Gatos Creek (above Lexington Reservoir).

Temporal Representation:

Environmental Conditions:

These data were collected hourly and thus represent the full range of environmental conditions present in this creek.

QAPP Information:

QAPP Information Reference(s):

Document supporting the data collection of water temperature on Los Gatos Creek from 2000-2012.