Directed Actions

The Delta Science Program funds directed action science investigations when clearly defined scientific research or advice is needed quickly or when an important opportunity would be lost if the proposal had to go through a competitive bid funding process. With directed actions, there is typically only one entity (individual or team) that is qualified and available to do the work within the desired timeframe. More information about directed actions can be found in the Delta Science Plan, Appendix K.

Intertidal Habitat Restoration

Project Title: McCormack-Williamson Tract

Primary Investigators: Carson Jeffres (UC Davis) and Josh Viers (UC Merced)

Project type: Directed action

Project term: 6.30.2016 - 6.30.2019

Project summary:

Restoration of intertidal habitat within the Delta has been highlighted as a target for restoring both physical process and threatened and endangered species that reside or migrate through the Delta. McCormack-Williamson Tract provides an opportunity to restore a gradient from subtidal to floodplain. This project explores the critical linkages between physical habitat processes, food web dynamics, and ultimate persistence of native fish populations. This will be accomplished by conducting monitoring, modeling, and synthesis in these thematic areas: 1) aquatic food web and carbon flux; 2) hydrodynamic and hydrospatial models; and 3) high resolution water quality and isoscape mapping.

Larval Sturgeon Physiology

Project Title: Assessment of temperature and nutritional dependent physiological processes in larval green and white sturgeon

Primary Investigators: Nann A. Fangue, Jamilynn B. Poletto, Richard E. Connon, Anne E. Todgham (UC Davis)

Project Type: Directed action

Project term: 6.30.2016 - 6.30.2019

Project summary:

The overarching goal of this project is to quantify the physiological, biochemical, and behavioral changes in green and white sturgeon larvae in response to altered rearing conditions. In doing so, we hope to elucidate optimal rearing conditions, where hatching success is highest, larval deformities are lowest, growth and swimming capacity are maximized, and thermal tolerance is widest. Understanding the sensitivity of early life stages to anthropogenic stressors is a critical step in reversing population declines because eggs, larvae and juveniles are often less resilient than adults to habitat disturbances. The findings from this project will allow us to inform water management initiatives which protect the most vulnerable life stages of sturgeon, with the ultimate goal of increasing recruitment rates and population abundances.

Salmon Response to Flows

Project Title: Monitoring juvenile spring-run Chinook salmon in response to climate-driven flows in the San Joaquin River and south Delta

Primary Investigators: Andrew Rypel, Nann Fangue, Eric Chapman, Gabriel Singer (UC Davis)

Project Type: Directed action

Project Term: 6.30.2016 - 12.31.2019

Project Summary:

The purpose of this project is to collect and interpret data regarding the movement and survival of the newly introduced spring-run Chinook salmon in the San Joaquin River and estuary. These data will help to inform researchers of the relative success of these fish and the factors (abiotic and biotic) contributing to successful seaward migration. The project will provide information that can be used to gauge how hospitable the newly revitalized migration corridor is to the smolts being reintroduced to the San Joaquin River.

Operation Baseline

The Sacramento Regional County Sanitation District (Regional San) is currently constructing new treatment facilities at the Sacramento Regional Wastewater Treatment Plant (SRWTP), at a cost of approximately $1.5 B, which are due to be operational in 2021. These upgrades will dramatically reduce total nitrogen levels and alter the concentrations of different forms of nitrogen in the Sacramento River. As a sub-component of the upgrade coming online, the nutrient composition of the treated wastewater effluent may be reduced, but there are not fixed compliance dates for these interim steps.

To understand what effects these changes may have on the Delta ecosystem, a baseline needs to be established. Operation Baseline is a set of innovative studies funded by the Delta Stewardship Council to fulfill this need. The studies will begin to assess the current state of nutrients, aquatic vegetation, and the food web in areas that may be affected by the changes in nutrient loading. These studies lay the groundwork to enable comparisons between present and future conditions.

For access to the Operation Baseline Science and Monitoring Needs Report, please contact

Key Study Questions to Assess Baseline Conditions

  1. What are the current fates of nutrients from wastewater treatment plant effluent, and how do these nutrients affect the Delta food web?
  2. What is the current phytoplankton functional group composition and size distribution?
  3. What are current phytoplankton, submerged aquatic vegetation, floating aquatic vegetation, and zooplankton growth rates, nutrient uptake rates, and sources of nutrients?
  4. How are north Delta wetland and open water food webs currently linked to sources, concentrations, chemical forms, and geographic distributions of nutrients?
  5. Where are the ‘hot spots’ of nutrient changes in the Delta that traditional monitoring methods miss?
  6. What data are needed to build, calibrate, and validate linked mechanistic models of the hydrology, biology, chemistry, and physics within the Delta?

Pilot Studies

  • For more information, email
  • Conceptual Framework (USGS and SFEI-ASC)
  • Pilot Studies
    • Nutrient concentrations, transformation rates, and links to the food web (USGS):
      • Phytoplankton (CSU Maritime Academy)
      • Zooplankton (Romberg Tiburon Center, SFSU)
      • Method to improve monitoring using fixed stations coupled with high-speed boat measurements (USGS)
      • Evaluate the usefulness of stable isotopes to trace nutrients from effluent water (USGS)

Suisun-Delta Nutrient Modeling

Project Title: Bay-Delta hydrodynamic-biogeochemical modeling

Primary Investigators: Dave Senn and Zhenlin Zhang, Alexandra King (San Francisco Estuary Institute - Aquatic Science Center), and Rusty Holleman (UC Davis)

Project Type: Directed action

Project Term: 2.17.2017 - 6.30.2019

Project Summary:

Given the importance of phytoplankton productivity for supporting fish populations, including those on endangered or threatened lists, management decisions in the Bay-Delta need to be informed by quantitative understanding of the multiple factors that influence blooms, and the complex interplay among those factors. With the multiple physical and biological factors influencing phytoplankton biomass, numerous nutrient sources, and complex nutrient transformations, numerical models are essential tools for developing this integrated quantitative understanding. This project is using modeling to inform major management decisions related to nutrients in the Bay-Delta. For access to the Suisun-Delta Biogeochemical Modeling Final Report, please contact

Effects of Delta Island Flooding

Project Title: Effects of Delta island flooding

Primary Investigator: John DeGeorge

Project Type: Directed action

Project Term: 6.30.2017 - 6.30.2020

Project Summary:

The purpose of this project is to better understand the effects of levee breaches (whether by Mother Nature, or planned restoration projects), and island flooding in the Delta. The goals is to provide information regarding changes in water surface elevation, salinity, flow patterns, tidal energy, along with many other metrics. The long-term goal is to provide management and decision-makers with powerful, yet user-friendly, useable information that is necessary for making decisions regarding alternative future scenarios in the Delta ecosystem. This project will provide technical memos describing all aspects of the study, including well thought through modeling results and presentations. There may also be a web-based modeling results viewer that will enable end-users to quickly and efficiently filter through the data, and visually present the data in an easily digestible fashion.

Examples of where these products may be useful and useable:

  • SWP and CVP planning, operations, and regulation
  • Water Quality Control Plans, permits, and regulations
  • Risk assessment for Delta levee failures
  • Delta levee investment decisions
  • Adaptive management of habitat restoration projects
  • Emergency drought barriers - water quality and fish movement