EPA provides technical support and regulatory assistance for priority activities designed to address water quality and aquatic life protection in the Delta. Recent documents and products are provided below along with technical products that supported setting water quality standards in the mid 1990s. EPA has provided comments on the State’s proposed updates to the SF Bay Delta Water Quality Control Plan.

• 2020: Chinook Salmon Interpopulation Thermal Tolerance Investigation
• 2017: Advancement of Salinity and Flow Monitoring in the San Francisco Bay Delta
• 2016: Chinook Salmon Thermal Tolerance Investigation
• 2015: Salinity Gradient and Fish Abundance & Distribution Maps
• 2011: EPA Low Salinity Zone Workshop
• 2010: Flow Criteria for the Sacramento-San Joaquin Delta Ecosystem
• 2008: California State Water Resources Control Board Strategic Workplan for the Bay-Delta
• 1993: Managing Freshwater Discharges to the SF Bay Delta Estuary: the Scientific Basis for an Estuarine Standard

2020: Chinook Salmon Interpopulation Thermal Tolerance Investigation

EPA funded temperature experiments with multiple runs of Chinook salmon in Oregon and California to improve the state of knowledge about thermal performance of Chinook salmon and explore whether populations near the species’ southernmost distribution limit (i.e., California’s Central Valley) exhibit a higher thermal tolerance than more northerly populations. Results are available in the final report, Interpopulation Variation among Juvenile Chinook Salmon from California and Oregon.

2017 Advancement of Salinity and Flow Monitoring in the San Francisco Bay Delta

EPA worked with partners to describe the utility and approximate cost of expanding the salinity water quality monitoring network along the axis of the San Francisco Estuary from Suisun Bay to Rio Vista on the Sacramento River. The expanded monitoring network would generate data used to increase the precision of water quality compliance and assessment methods, salinity and hydrodynamic forecasting tools, and targeted water management actions.

2016 Chinook Salmon Thermal Tolerance Investigation

EPA funded temperature experiments with fall run Chinook salmon to improve the state of knowledge about thermal performance and thermal tolerance of Central Valley Chinook salmon. Results are available in the final report, Thermal Performance in Juvenile Hatchery Oncorhynchus Tshawytscha: Aerobic Scope Tests. Over a Range of Environmental Temperatures. Additional experiments are underway to assess the thermal performance and thermal tolerance of the endangered Sacramento River winter run Chinook salmon, with results expected in 2020.

2015 Salinity Gradient and Fish Abundance & Distribution Maps

EPA created maps for six fish species that show changes in abundance and distribution as they relate to seasonal changes in the salinity gradient over a 33-year time period. The maps visualize established salinity-abundance relationships and show how distribution has changed over time in the San Francisco Bay Delta Estuary.

2011 EPA Low Salinity Zone Workshop

EPA convened a technical workshop to evaluate the relationship between the low salinity zone (where marine and freshwater mix) and aquatic life populations including fish, zooplankton, and phytoplankton. Workshop products were provided to the State Water Resources Control Board (SWRCB) to use as they consider updates to water quality standards intended to protect aquatic life.

2010 Flow Criteria for the Sacramento-San Joaquin Delta Ecosystem

• Delta Flow Criteria at California State Water Resources Control BoardExit
• Delta Flow Criteria Presentation: Presentation by Dr. Bruce Herbold, EPA R9 Fisheries Biologist, to the State Water Resources Control Board at the March 22 - 24 Delta Flow Criteria hearing.
• Delta Flow Criteria Written Comments: Written comments by Dr. Bruce Herbold, EPA R9 Fisheries Biologist, to the State Water Resources Control Board following the March 22 - 24 Delta Flow Criteria hearing.

2008 California State Water Resources Control Board Strategic Workplan for the Bay-Delta

• Strategic Workplan at California State Water Resources Control BoardExit
• EPA comments on the Bay Delta Strategic Workplan
• EPA comments on the March 19, 2008 SWRCB Public Workshop on development of San Francisco Bay/Sacramento-San Joaquin River Delta Strategic Workplan

1993 Managing Freshwater Discharges to the SF Bay Delta Estuary: the Scientific Basis for an Estuarine Standard

• Managing Freshwater Discharges to the SF Bay Delta Estuary: the Scientific Basis for an Estuarine Standard