Evapotranspiration Water Use Analysis of Saltcedar and Other Vegetation in the Mojave River Floodplain, 2007 and 2010

U.S. Bureau of Reclamation (USBR) | August 15th, 2011

The Mojave Water Agency Water Supply Management Study, Phase 1 Report (Study) was developed to provide technical information on vegetation water usage in the Mojave River

The Mojave Water Agency Water Supply Management Study, Phase 1 Report (Study) was developed to provide technical information on vegetation water usage in the Mojave River floodplain, with emphasis on saltcedar. Study analyses included 2007 and 2010 classification of native and non-native vegetation, vegetation evapotranspiration (ET) modeling1, lidar elevation map development, groundwater mapping, and water evapotranspiration cost calculations. Results are presented as a whole and by Mojave Water Agency (MWA) subarea boundaries: Alto, Alto Transition, Centro, and Baja.

Evidence of Landlocked Chinook Salmon Populations in California

North American Journal of Fisheries Management (Taylor & Francis) | November 10th, 2015

Natural reproduction of adfluvial Chinook Salmon Oncorhynchus tshawytscha has been documented in their native and introduced range but not in California, the southern end

Natural reproduction of adfluvial Chinook Salmon Oncorhynchus tshawytscha has been documented in their native and introduced range but not in California, the southern end of their native range. A combination of anecdotal evidence and survey data suggests that successful spawning by Chinook Salmon reared in California reservoirs could be common. The planted juveniles are often from different basins and are genetically distinguishable from local salmon populations below reservoirs. Consequently, the possibility of behavioral and genetic interactions may lead to complications of restoration efforts via trap and haul programs. The full extent of this phenomenon needs to be documented before trap and haul programs are initiated to reintroduce salmon above reservoirs.

Examining the causes and consequences of hybridization during Chinook salmon reintroductions: using the San Joaquin River as a restoration case study of management options

University of California, Davis (UC Davis) | June 15th, 2014

Successful salmonid restoration efforts depend upon an understanding of the evolutionary processes that historically shaped population diversity, as well as the realities

Successful salmonid restoration efforts depend upon an understanding of the evolutionary processes that historically shaped population diversity, as well as the realities of currently available, altered river systems. Habitat alterations over the past century have dramatically changed the ecological forces that shaped salmonid speciation and evolution, bringing formerly separate and distinct populations into contact and in some cases leading to hybridization. Hybridization can threaten the genetic diversity within salmonid species and may affect the outcomes of restoration efforts. Here we use the San Joaquin River Restoration as a case study to discuss some of the genetic challenges of Chinook salmon restoration in a newly reopened habitat. We discuss a range of genetic management strategies—from passive reintroduction to tightly managed, active reintroduction—and the strengths and weaknesses of each approach.

Existing Accessible Modeling Tools Offer Limited Support to Evaluation of Impact Investment in Rangeland Ecosystem Services

Frontiers in Sustainable Food Systems (Frontiers) | September 24th, 2019

Privately owned rangelands in the western US support many ecosystem services and are threatened by financial incentives favoring conversion to housing development and m

Privately owned rangelands in the western US support many ecosystem services and are threatened by financial incentives favoring conversion to housing development and more intensive forms of agriculture. Recognizing this threat, the impact investment community has identified rangeland management as a potential investing strategy to produce financial returns while preserving or enhancing the ecosystem services provided by intact rangelands. This strategy is based primarily on the notion that a capital-intensive conversion from continuous to rotational grazing can financially sustain rangelands through a combination of increased productivity and potentially monetized ecosystem service flows. The potential for these gains is supported by compelling anecdotal evidence, yet a robust body of scientific literature based on rigorous field experiments has not supported those claims, nor produced transferrable estimates of the benefits provided by rotational grazing of livestock (particularly cattle in the western US). Therefore, to demonstrate investment viability and measure investment success, impact investors will likely need to address these well-documented disconnects through some combination of monitoring and process-based modeling. This study examines the extent to which existing modeling tools are up to this task, by assessing the ability of two process-based models to represent four specific rotational grazing benefits put forth by impact investors, using a ranch in northeastern Wyoming as a case study. Using the Soil Water Assessment Tool, we simulated high magnitude changes in the water balance from surface runoff to evapotranspiration, which may be a benefit or negative impact depending on context (Benefit 1). We simulated a decrease in soil water storage under rotational grazing, which directly contradicts the outcome assumed in investment literature (Benefit 2). Using the InVEST beta Rangeland Production Model (based on the Century ecosystem model), we simulated increased biomass productivity (Benefit 3) under rotational grazing, which enhanced animal performance under some management parameters but negatively impacted it in others (Benefit 4). We conclude that the impact investing community will likely find greater success through a shift to objective-oriented ranch management, rather than a specific focus on rotation, and will also need additional investment in science and monitoring to demonstrate benefits.

Expert review of the sediment screening guidelines for the beneficial reuse of dredged material in San Francisco Bay, Workshop Summary Report

Publisher not available | March 17th, 2020

Exploring scientific and management implications of upper trophic level food webs in the Delta

Delta Stewardship Council (Delta Council) | April 17th, 2024

The Sacramento-San Joaquin Delta (the Delta) has complex and evolving ecosystems characterized by multiple food webs that vary in time and space. Here, food webs are defi

The Sacramento-San Joaquin Delta (the Delta) has complex and evolving ecosystems characterized by multiple food webs that vary in time and space. Here, food webs are defined as the network of species interactions (competition, predation) and interactions with their environment that are related through the flow of energy through the ecosystem (e.g., Paine 1980). Physical modifications, in addition to the introduction of non-native species and the changing climate, have significantly altered the structure and energetic pathways of the food webs for decades. The science clearly suggests that predicting the impacts of habitat restoration, fisheries, changes in environmental drivers (e.g., climate, changes in nutrient loading, invasive species) on the ecological carrying capacity and productivity of the Delta, as well as the bioaccumulation of contaminants on species or the ecosystem, requires an understanding of food web processes.

Exposure history determines pteropod vulnerability to ocean acidification along the US West Coast

Nature Portfolio (Springer Nature) | July 3rd, 2017

The pteropod Limacina helicina frequently experiences seasonal exposure to corrosive conditions (Ωar  < 1) along the US West Coast and is recognized as

The pteropod Limacina helicina frequently experiences seasonal exposure to corrosive conditions (Ωar  < 1) along the US West Coast and is recognized as one of the species most susceptible to ocean acidification (OA). Yet, little is known about their capacity to acclimatize to such conditions. We collected pteropods in the California Current Ecosystem (CCE) that differed in the severity of exposure to Ωar conditions in the natural environment. Combining field observations, high-CO2 perturbation experiment results, and retrospective ocean transport simulations, we investigated biological responses based on histories of magnitude and duration of exposure to Ωar < 1. Our results suggest that both exposure magnitude and duration affect pteropod responses in the natural environment. However, observed declines in calcification performance and survival probability under high CO2 experimental conditions do not show acclimatization capacity or physiological tolerance related to history of exposure to corrosive conditions. Pteropods from the coastal CCE appear to be at or near the limit of their physiological capacity, and consequently, are already at extinction risk under projected acceleration of OA over the next 30 years. Our results demonstrate that Ωar exposure history largely determines pteropod response to experimental conditions and is essential to the interpretation of biological observations and experimental results.

Extreme and compound events in lakes

Nature Portfolio (Springer Nature) | August 19th, 2025

Key points Lake heatwaves have increased in average intensity, average duration and total duration globally, at rates of 0.15 ± 0.3 °C per decade, 2.1 

Key points Lake heatwaves have increased in average intensity, average duration and total duration globally, at rates of 0.15 ± 0.3 °C per decade, 2.1 ± 3.1 days per decade and 8.8 ± 7.6 days per decade, respectively, since the 1980s. The probability of lake heatwave events is three times more likely in a 1.5 °C warming scenario and 25 times more likely in a 3.5 °C scenario compared with pre-industrial conditions. Half of the world’s largest lakes experienced declines in water storage between 1992 and 2020, accompanied by corresponding reductions in surface extent. Extreme events in lakes can cause considerable impacts, including the onset of hypoxia, harmful algal blooms, disruption of food webs and loss of ecosystem services. Basin-scale anthropogenic stressors, such as nutrient enrichment, land-use change and water withdrawal, interact with climate extremes to increase the frequency, intensity and ecological consequences of in-lake extremes.

Extremophile hotspots linked to containerized industrial waste dumping in a deep-sea basin

Oxford University Press (OUP) | September 9th, 2025

Decaying barrels on the seafloor linked to DDT contamination have raised concerns about the public health implications of decades old industrial waste dumped off the coas

Decaying barrels on the seafloor linked to DDT contamination have raised concerns about the public health implications of decades old industrial waste dumped off the coast of Los Angeles. To explore their contents, we collected sediment cores perpendicular to five deepsea barrels. The concentration of DDT and its breakdown products were highly elevated relative to control sites yet did not vary with distance from the barrels, suggesting that they were not associated with the contamination. Sediment cores collected through white halos surrounding three barrels were enriched in calcite and had elevated pH. The associated microbial communities were low diversity and dominated by alkalophilic bacteria with metagenome-assembled genomes adapted to high pH. A solid concretion sampled between a white halo and barrel was composed of brucite, a magnesium hydroxide mineral that forms at high pH. Based on these findings, we postulate that leakage of containerized alkaline waste triggered the formation of mineral concretions that are slowly dissolving and raising the pH of the surrounding sediment pore water. This selects for taxa adapted to extreme alkalinity and drives the precipitation of “anthropogenic” carbonates forming white halos, which serve as a visual identifier of barrels that contained alkaline waste. Remarkably, containerized alkaline waste discarded >50 years ago represents a persistent pollutant creating localized mineral formations and microbial communities that resemble those observed at some hydrothermal systems. These formations were observed at one-third of the visually identified barrels in the San Pedro Basin and have unforeseen, long-term consequences for benthic communities in the region.

Facilitating Adaptive Management in California’s Sacramento–San Joaquin Delta

University of California, Davis (UC Davis) | July 1st, 2017

Uncertainties in understanding ecosystems increase the risk that management will fail to achieve desired results. Adaptive management is a structured, iterative applicati

Uncertainties in understanding ecosystems increase the risk that management will fail to achieve desired results. Adaptive management is a structured, iterative application of science-based knowledge to reduce uncertainties and build flexibility into decision-making. However, adaptive management is more easily planned than implemented, and it is only beginning to be applied in the California’s Sacramento–San Joaquin Delta. We draw from two assessments of adaptive management in the Delta and examples of its use elsewhere to suggest how the process can be facilitated. Although a highly structured adaptive-management process may not always be needed, several elements are essential. Adaptive management should begin by clearly identifying the problem, goals, and objectives; recognizing uncertainties; identifying decision points and alternative approaches; recognizing when adjustments are needed and having the flexibility to make them; and considering societal and political constraints. Model complexity should be matched to that of the system and management needs; experiments can help unravel causal relationships. Monitoring, analyses, and syntheses require comprehensive data-management systems. More frequent and organized communications among scientists, managers, stakeholders, and decision-makers are necessary. We propose the establishment of an “Adaptive Management Team” to coordinate efforts across the management spectrum of the Delta and to provide guidance and link individual projects to shared approaches and experiences. Reliable long-term support will be needed to assess results of management actions, adjust approaches where improvement is likely, and strive toward the legislated goals of enhancing the Delta ecosystem while also providing reliable water supplies to much of California, and doing both these things in a manner that protects values of the Delta as a place where people live and work.