At the request of the U.S. Bureau of Reclamation (USBR), an ad hoc committee of the National Academies of Sciences, Engineering, and Medicine is conducting a biennial review of the monitoring, modeling, and other relevant scientific activities and initiatives that support the long-term operations of the Central Valley Project (CVP) and the State Water Project (SWP) (collectively the Projects). The Projects consist of coordinated federal-state water operations that annually move millions of acre-feet of water via dams, canals, tunnels, pumps, and power plants from Northern California to a wide variety of water users throughout the state, including municipalities, agriculture, industries and wildlife refuges. Operation of these water systems affects six fish protected under the Endangered Species Act: the southern distinct population segment of North American green sturgeon, California Central Valley steelhead trout, Central Valley spring-run Chinook salmon, Sacramento River winter-run Chinook salmon, longfin smelt, and Delta smelt.

In its first cycle, the committee assessed the state of science, monitoring, and modeling for Old and Middle River flow management, Shasta coldwater pool management, and the Summer-fall Delta Smelt habitat action. In its second cycle, the committee will:

• Evaluate progress toward meeting the CVP’s long-term operational goals.
• Discuss significant accomplishments of the CVP during the biennial report period.
• Discuss the role of ecosystem metrics for improving CVP management and decision-making. A more specific discussion of item 3 is provided below.

Status and trend monitoring in the California Bay-Delta watershed, maintained by various entities and funded primarily by the USBR and the California Department of Water Resources (CDWR), shows continued ecological decline in listed fish species despite modifications and improvements to water operations, as well as investments in habitat restoration and facility improvements. USBR and CDWR seek advice from the National Academies on updating their monitoring enterprise in the estuary to better characterize and provide the information necessary to test mechanistic hypotheses of ecosystem functions impacted by CVP and SWP actions. USBR and CDWR want to ensure their monitoring efforts provide robust, objective information on the effects of the Projects on the environment within an ecosystem trophic framework that consists of (1) flows and the nutrients carried by flows, (2) primary productivity including algae and macrophytes, (3) secondary productivity including zooplankton and clams, (4) consumers (juvenile salmonids, sturgeon, smelts, and others), and (5) the resulting native and non-native community of predators and prey. Improvements in monitoring are sought in order to manage the Projects with increased certainty and improve confidence in the outcome of implemented actions.

The following questions will guide the work of the committee:

1. What ecosystem metrics would serve as informative indicators linking ecosystem function and health to the Projects?
2. What innovations in monitoring design, field and laboratory techniques, statistical frameworks, and other relevant aspects of monitoring are available or could be developed to increase accuracy and resolution when evaluating the effectiveness of operational decisions and investments?
3. Are the current USBR/CDWR monitoring systems sufficiently robust to capture changes in ecosystem functions in response to the Projects and changing conditions? How can USBR/CDWR build robustness into their monitoring networks to better understand changing ecosystem functions under changing conditions?
4. Where can an observational network, numerical models, and artificial intelligence tools be used to predict or forecast changes in ecosystem metrics due to the Projects?

The review will focus primarily on the monitoring data used to calibrate and validate models of ecosystem processes in the Delta (status and trend monitoring), making it essential for the committee to understand the models and tools used in the management of the system now and in the future.