This study analyzes 12 notch scenarios in the Fremont Weir in terms of entrainment of juvenile salmon. The goal is to quantify the relative entrainment rates (between 0 and 1) across the suite of scenarios and to identify possible strategies for enhancing entrainment outcomes. This study does not predict future entrainment as models generally do not predict future outcomes so much as highlight trends
The goal of this research is to better understand how climate change will affect fishes with different life histories and habitat associations across the San Francisco Estuary. Existing datasets will be incorporated in synthetic analyses and cutting-edge statistical models to identify fish community responses to climate, flows, and habitats along the estuarine salinity gradient. This synthesis-science project will use rich long-term datasets that have been collected by Bay-Delta researchers for decades that will then be analyzed in a reproducible and open science framework. It will also support efforts by the Interagency Ecological Program's Climate Change Project Work Team.
Description In a collaborative effort between CA Department of Water Resources, US Bureau of Reclamation, CA Department of Fish and Wildlife, United States Geological Survey, San Francisco State University, and UC Davis, this study will investigate the role of augmented summer and fall flows in the Yolo Bypass and North Delta areas on lower trophic food web dynamics and the benefits to listed fish species. Using both continuous and discrete sampling approaches, this study will relate hydrologic patterns to chlorophyll-a, nutrients and primary productivity, plankton densities and composition (phytoplankton and zooplankton), contaminant concentrations, as well as water quality parameters such as electrical conductivity, turbidity, temperature, and dissolved oxygen. In addition, caged hatchery Delta Smelt will be monitored to determine the effects of the managed flow action and increased food web productivity on fish survival, growth, and behavior. Need Due to the food-limited nature of the San Francisco Estuary, it is critical to understand mechanisms that result in successful food web productivity including phytoplankton blooms. Food limitation is one of the primary hypothesized causes of the Pelagic Organism Decline. In 2011 and 2012 there was evidence that a moderate Yolo Bypass flow pulse during fall agricultural drainage periods was followed by phytoplankton blooms in the lower Sacramento River. Managed flow actions in the following years showed an increase in food web productivity could be repeated; however, results varied across years and flow actions indicating more research is warranted to understand correlations between flow and abiotic conditions, and the biological response of the food web. The increases of summer/fall flows in North Delta, has been considered a management strategy as part of complying with USFWS Delta Smelt Biological Opinion Action 4. The augmentation of flows through the Yolo Bypass/North Delta is also included as one of several Delta Smelt Resiliency Strategies by Natural Resources Agency. Objectives: Determine if managed flow actions through the Yolo Bypass stimulate increased primary productivity locally and downstream, and if it is repeatable. Characterize how nutrients, chlorophyll and plankton (composition and density) in the Toe Drain, Cache Slough Complex, and lower Sacramento River change in response to flow pulses. Determine if nutrient subsidies of the source water and downstream are limited by abiotic and biotic factors. Characterize spatial differences and transport of pesticide contaminants in the Yolo Bypass in response to the flow actions. Determine survival, growth and behavior of caged hatchery Delta Smelt before and after the flow action in the Yolo Bypass.
The Delta is a critical area for sustainable water management, facing significant challenges due to climate change. One of these challenges is in understanding and mitigating maladaptation – climate-aligned actions that may increase vulnerabilities or reduce adaptive capacity. Given the uncertainties surrounding climate change, management actions that seek to achieve high-level goals of climate change adaptation while accounting for maladaptation must be robust, ensuring adequate, multicriteria performance across all climate futures. This work responds to two gaps: (1) the absence of tools for assessing the performance of management actions in the Delta under hydroclimatic uncertainty and (2) a lack of research that explores how stakeholders can account for maladaptation in water governance. Among Delta stakeholders and researchers alike, the discourse and science surrounding ecological flow guidelines, the social complexities of water governance, and the use of integrated climate models to inform robust and adaptive decisions is active and rapidly advancing. This positions the Delta not only as an ideal case study for the academic study of maladaptation, but also as one that is of immediate relevance to stakeholders, responding to several Delta Management Needs (Science Actions 3B, 6E, and 1A) as they concern open science and the exploration of the Delta as a socioecological system and the facilitation of decision-making under climate change and its associated uncertainties.
The Sacramento River and its tributaries serve as critical habitat for the green sturgeon, listed as federally threatened due to its declining population and the impacts of anthropogenic activities such as dam operations and water extraction. We currently lack an understanding of the relationship between flow regimes and sturgeon migration, which is essential for developing effective management strategies to support the species' conservation and for required analysis under state and federal law. By modeling this relationship, this project will contribute to more informed water management, leading to fewer litigation risks for agencies and better outcomes for sturgeon.
This project will model the effects of flow regimes on adult Southern Distinct Population Segment (sDPS) green sturgeon migration within the Sacramento River basin to enhance sturgeon conservation and water management. Specifically, the research will model how flows and temperature affect adult green sturgeon spawning migration. The model will be used to forecast sturgeon movements under various flow scenarios, and the model, the results, and an explanation of their significance will be widely distributed via a website (with a publicly accessible modeling app), a policy brief, a public workshop, and other outreach.
