Risks of ocean acidification in the California Current food web and fisheries: ecosystem model projections

Wiley | January 12th, 2017

The benefits and ecosystem services that humans derive from the oceans are threatened by numerous global change stressors, one of which is ocean acidification. Here, we d

The benefits and ecosystem services that humans derive from the oceans are threatened by numerous global change stressors, one of which is ocean acidification. Here, we describe the effects of ocean acidification on an upwelling system that already experiences inherently low pH conditions, the California Current. We used an end‐to‐end ecosystem model (Atlantis), forced by downscaled global climate models and informed by a meta‐analysis of the pH sensitivities of local taxa, to investigate the direct and indirect effects of future pH on biomass and fisheries revenues. Our model projects a 0.2‐unit drop in pH during the summer upwelling season from 2013 to 2063, which results in wide‐ranging magnitudes of effects across guilds and functional groups. The most dramatic direct effects of future pH may be expected on epibenthic invertebrates (crabs, shrimps, benthic grazers, benthic detritivores, bivalves), and strong indirect effects expected on some demersal fish, sharks, and epibenthic invertebrates (Dungeness crab) because they consume species known to be sensitive to changing pH. The model's pelagic community, including marine mammals and seabirds, was much less influenced by future pH. Some functional groups were less affected to changing pH in the model than might be expected from experimental studies in the empirical literature due to high population productivity (e.g., copepods, pteropods). Model results suggest strong effects of reduced pH on nearshore state‐managed invertebrate fisheries, but modest effects on the groundfish fishery because individual groundfish species exhibited diverse responses to changing pH. Our results provide a set of projections that generally support and build upon previous findings and set the stage for hypotheses to guide future modeling and experimental analysis on the effects of OA on marine ecosystems and fisheries.

River-Aquifer Interactions, Geologic Heterogeneity, and Low-Flow Management

U.S. Geological Survey (USGS) | ?

Low river flows are commonly controlled by river-aquifer exchange, the magnitude of which is governed by hydraulic properties of both aquifer and aquitard mater

Low river flows are commonly controlled by river-aquifer exchange, the magnitude of which is governed by hydraulic properties of both aquifer and aquitard materials beneath the river. Low flows are often important ecologically. Numerical simulations were used to assess how textural heterogeneity of an alluvial system influences river seepage and low flows. The Cosumnes River in California was used as a test case. Declining fall flows in the Cosumnes River have threatened Chinook salmon runs. A ground water–surface water model for the lower river basin was developed, which incorporates detailed geostatistical simulations of aquifer heterogeneity. Six different realizations of heterogeneity and a homogenous model were run for a 3-year period. Net annual seepage from the river was found to be similar among the models. However, spatial distribution of seepage along the channel, water table configuration and the level of local connection, and disconnection between the river and aquifer showed strong variations among the different heterogeneous models. Most importantly, the heterogeneous models suggest that river seepage losses can be reduced by local reconnections, even when the regional water table remains well below the riverbed. The percentage of river channel responsible for 50% of total river seepage ranged from 10% to 26% in the heterogeneous models as opposed to 23% in the homogeneous model. Differences in seepage between the models resulted in up to 13 d difference in the number of days the river was open for salmon migration during the critical fall months in one given year.

Rivers that Depend on Aquifers: Drafting SGMA Groundwater Plans with Fisheries in Mind

Golden Gate University (GSU) | April 12th, 2018

In California, surface waters have historically been regulated as if they were unconnected to groundwater. Yet, in reality, surface waters and groundwater are often hydro

In California, surface waters have historically been regulated as if they were unconnected to groundwater. Yet, in reality, surface waters and groundwater are often hydrologically connected. Many of the rivers that support fisheries such as salmon and trout are hydrologically dependent on tributary groundwater to maintain instream flow. This means that when there is intensive pumping of tributary groundwater the result can be reductions in instream flow and damage to fisheries. For this reason, stakeholders concerned about adequate instream flows for fisheries in California’s rivers, streams and creeks need to be effectively engaged in the implementation of California’s Sustainable Groundwater Management Act (SGMA). Consider the Scott River in Northern California, part of the larger Klamath River Basin. Nearby groundwater contributes to the Scott River. When high volumes of groundwater are extracted from nearby wells, it depletes the Scott River’s instream flow with adverse impacts on salmon and steelhead trout. As discussed further in Section VI of this guidebook, this has led to litigation over the application of California public trust law to groundwater extraction affecting Scott River instream flows, and efforts to use SGMA to ensure that groundwater pumping near the Scott River is compatible with the instream flow needs of fisheries. Situations similar to the Scott River surface and groundwater basin are unfolding throughout California. On a statewide basis, how pervasive is the effect of groundwater pumping on surface water flows? Research by Maurice Hall of the Environmental Defense Fund, utilizing the California Department of Water Resources Central Valley Groundwater Surface Flow Model, provides us with some sense of the magnitude of the problem. In a May 2018 presentation, Hall reported: What the model showed us is that early in the 1900s, 1940s and 1950s, the Sacramento River received a net inflow from the groundwater of something like 1 million acre feet a year…Since that time, the groundwater levels have gone down, and the amount of water that has flowed into the Sacramento River from the surrounding groundwater has gone down accordingly to the point that when we were doing this modeling around 2010, it appeared that on average, the Sacramento River lost just about as much as it gained from the surrounding groundwater in the valley floor. This is the Sacramento River and all of its tributaries upstream of the Sacramento…So the net effect over that period is there was roughly on average 900,000 acre-feet per year less water showing up in the  Sacramento River at Sacramento.” (Hall and O’Brien). SGMA was enacted in 2014. Pursuant to SGMA, by June 2017 a groundwater sustainability agency was required to be designated for each groundwater basin in California. Each groundwater sustainability agency in high and medium priority basins must prepare and adopt a Groundwater Sustainability Plan (SGMA Groundwater Plan) by 2020 if the basin is deemed to be in a critical state of overdraft or 2022 for all remaining high and medium priority basins. Each SGMA Groundwater Plan must detail how the groundwater basin will be managed to avoid overdraft conditions and, importantly for fisheries, to avoid adverse impacts on hydrologically connected surface waters. Although groundwater sustainability agencies and fishery stakeholders recognize that the groundwater-surface water connection needs to be addressed in SGMA Groundwater Plans, at present there is limited guidance on how to do this. That is, what are the specific types of information, modeling, monitoring, and pumping provisions that should be included in SGMA Groundwater Plans to ensure that groundwater extraction does not cause significant adverse impacts on fisheries? The purpose of this guidebook is to provide such guidance.

Ruling on Plaintiffs’ Motion for Preliminary Injunction, Case No. Bcv-22-103220-Gap, Bring Back the Kern et al v. City of Bakersfield et al

Superior Court of California, County of Kern | October 30th, 2023

SacPAS Fish Model: A model for emergence, migration and survival of Sacramento River salmon

Delta Stewardship Council (Delta Council) | November 1st, 2017

Sacramento River Temperature Task Group Annual Report of Activities October 1, 2013 through September 30, 2014

Delta Stewardship Council (Delta Council) | October 6th, 2014

Sacramento River Temperature Task Group Annual Report of Activities October 1, 2017 through September 30, 2018

Delta Stewardship Council (Delta Council) | November 21st, 2018

Sacramento Valley Salmon Resiliency Strategy June 2017

California Natural Resources Agency (CNRA) | June 2nd, 2017

The Sacramento Valley Salmon Resiliency Strategy (Strategy) is a science-based document that has been prepared by the State of California (State) to address specific near

The Sacramento Valley Salmon Resiliency Strategy (Strategy) is a science-based document that has been prepared by the State of California (State) to address specific near- and long-term needs of Sacramento River winter-run Chinook salmon (winter-run), Central Valley spring-run Chinook salmon (spring-run), and California Central Valley steelhead (steelhead). The Strategy mirrors the approach taken with the Delta Smelt Resiliency Strategy developed by the State in 2016: science-driven, focused, and designed to provide resource agencies, the public, Congress, and the California State Legislature with information critical to collaborative approaches to species resiliency. The Strategy relies heavily on the National Marine Fisheries Service Final Recovery Plan for winter-run, spring-run, and steelhead (NMFS 2014), and is guided by conceptual models of factors driving winter-run population dynamics at key life stages developed by the salmon and sturgeon assessment of indicators by life-stage (SAIL) teams (Johnson et al. 2016; Heublein et al. 2017). The actions are also supported, where indicated, by other salmonid recovery planning documents and efforts. The Strategy is an aggressive approach to improving species viability and resiliency by implementing specific habitat restoration actions. The State will take leadership roles in each action, although in all cases federal and local agency leadership, coordination, and partnerships are required for success. Recent successful restoration efforts led by local agencies and landowners demonstrate the importance and value of these collaborative partnerships. State agencies that could implement this Strategy include the California Natural Resources Agency, the Department of Water Resources (DWR) and the Department of Fish and Wildlife (DFW). The U.S. Bureau of Reclamation (Reclamation) will be a primary partner in many of the actions. In many cases, included actions will benefit an array of aquatic and terrestrial species. Coordination and alignment across various resource management agencies will ensure achievement of maximum public benefit. All of the actions will comply with applicable laws including the U.S. Endangered Species Act (ESA), California Endangered Species Act, California Environmental Quality Act, National Environmental Policy Act, and the federal Clean Water Act.

Salton Sea Fisheries Long-term Monitoring Sampling Report: Summer 2017

California Natural Resources Agency (CNRA) | July 13th, 2017

In early 2016, historic indices of tilapia abundance at the Salton Sea appeared to have reversed: tilapia fry were no longer observed in places where fish were regularly

In early 2016, historic indices of tilapia abundance at the Salton Sea appeared to have reversed: tilapia fry were no longer observed in places where fish were regularly visible in the past, piscivorous bird numbers at the lake were severely reduced, anglers were only catching a small fraction of past numbers of fish, and only a few small fish kills were observed. As observations of these conditions continued in early 2017, the question of whether the tilapia population was still viable was the impetus for the California Department of Fish and Wildlife (CDFW) to re-initiate gillnetting efforts.

Salton Sea Management Program Conceptual Project Implementation and Cost Estimates to Meet State Board Targets

California Natural Resources Agency (CNRA) | April 27th, 2017

The Salton Sea Management Program (SSMP) has developed a 10-year plan for Phase I that envisions a range of activities for habitat creation and dust management as

The Salton Sea Management Program (SSMP) has developed a 10-year plan for Phase I that envisions a range of activities for habitat creation and dust management as the Salton Sea recedes over 2018–2028. The California State Water Resources Control Board (SWRCB), through an order revising Order WRO 2002–0013, outlines annual and cumulative target areas for restoration through creation of habitat and dust suppression projects. These targets are defined for each year, ranging from a cumulative 500 acres by January 1, 2019, to a cumulative 29,800 acres by January 1, 2029, with a minimum 50 percent of the area being designated for fish and wildlife habitat projects. Areas around the sea are proposed for restoration projects, specifically at the southern end of the sea near the inflows of the Alamo and New rivers, and the northern end of the sea near the inflow of the Whitewater River. In a prior document (Salton Sea Management Plan Phase I: 10 Year Plan, March 2018), an overview of the project areas and activities was presented. This document presents a high-level plan for achieving the annual goals in the SWRCB order, by means of creation of wet habitat and dust control areas in different parts of the Salton Sea lakebed. This document identifies conceptual habitat ponds to be created, the associated wetted areas, and the additional dust control areas required to meet the order targets. For each of the conceptual project areas, there are estimates for berm lengths, heights, and needs for additional infrastructure, such as pumps and pipelines, causeways for equipment access, and levee extensions along river channels for flood protection of newly created habitat. Planned cross sections for the different types of linear structures are shown. Cost estimates are provided for each of the project areas over time to develop a total cost estimate. The conceptual habitat and dust control areas are based on the best current information on Salton Sea bathymetry, and demonstrate a reasonable path forward to attain the State Board order targets. The costs associated with these targets as presented in this document can be used for additional planning as part of the SSMP over the next decade. It is recognized that the actual footprints of individual projects may change in future years as better information becomes available on lakebed elevations, and relationships with other non-SSMP projects for habitat and dust control are better understood. These cost estimates are a refinement of estimates presented in the Salton Sea Management Plan Phase I: 10-Year Plan (March 2017). The cost estimates incorporate the best available cost information, and include the development of conceptual berm designs and supporting infrastructure, such as water diversions, pumps, and pipelines, and levees for river extensions. For these reasons, the cost estimate presented here supersedes the March 2017 estimate of $383 million for the 10-year implementation. But, all cost estimates at this stage are considered preliminary, and subject to revision as new field and construction data become available, and as designs are adjusted to best meet overall program needs. In the remainder of this document, two key topics are presented. In Chapter 2, there are estimates of the projected elevations of the Salton Sea over the 2018–2028 period, based on a hydrologic model of the sea. This is needed to allow estimation of exposed lakebed with the goal of constructing new habitat under dry conditions. Proposed conceptual project footprints, design and cost assumptions, and cost summaries are presented in Chapter 3.