Challenges Facing the Sacramento-San Joaquin Delta: Complex, Chaotic, or Simply Cantankerous?

Delta Stewardship Council (Delta Council) | April 9th, 2015

In 2014, the California Natural Resources Agency and the U.S. Department of the Interior asked the authors of this paper, as four former leaders of The Delta Science Prog

In 2014, the California Natural Resources Agency and the U.S. Department of the Interior asked the authors of this paper, as four former leaders of The Delta Science Program, to summarize the challenges faced by water supply and ecological resource managers in this critically important region of Northern California. They concluded that the challenges are so complex as to meet the definition of a “wicked” problem. Such problems can’t be ignored, defy straightforward characterization, and have no simple solutions. Yet they must be actively managed to maximize beneficial and minimize adverse outcomes. In this context, the following paper calls for Delta management to become more nimble and better coordinated.

Challenges Facing the Sacramento–San Joaquin Delta: Complex, Chaotic, or Simply Cantankerous?

University of California, Davis (UC Davis) | September 17th, 2015

Freshwater is a scarce and precious resource in California; its overall value is being made clear by the current severe drought. The Sacramento–San Joaquin Delta is a c

Freshwater is a scarce and precious resource in California; its overall value is being made clear by the current severe drought. The Sacramento–San Joaquin Delta is a critical node in a complex water supply system that extends throughout much of the western U.S. wherein demand is exceeding supply. The Delta also underpins a major component of the U.S. economy, helps feed a substantial part of the country, is a unique and valuable ecological resource, and is a place with a rich cultural heritage. Sustaining the Delta is a problem that manifests itself in many dimensions including the physical structure of the Delta, the conflicting demands for water, changing water quality, rapidly evolving ecological character, and high institutional complexity. The problems of the California Delta are increasingly complex, sometimes chaotic, and always contentious. There is general agreement that current management will sustain neither the Delta ecosystem nor high-quality water exports, as required under the Delta Reform Act, so there is a renewed urgency to address all dimensions of the problem aggressively. Sustainable management of the Delta ecosystem and California’s highly variable water supply, in the face of global climate change, will require bold political decisions that include adjustments to the infrastructure but give equal emphasis to chronic overuse and misuse of water, promote enhanced efficiency of water use, and facilitate new initiatives for ecosystem recovery. This new approach will need to be underpinned by collaborative science that supports ongoing evaluation and re-adjustment of actions. Problems like the Delta are formally “wicked" problems that cannot be “solved” in the traditional sense, but they can be managed with appropriate knowledge and flexible institutions. Where possible, it is advisable to approach major actions incrementally, with an eye toward avoiding catastrophic unexpected outcomes. Collaborative analyses of risks and benefits that consider all dimensions of the problem are essential. Difficult as the problems are, California has the tools and the intellectual resources to manage the Delta problem and achieve the twin goals of a reliable water supply and an ecologically diverse Delta ecosystem.

Changes in abundance and distribution of native and alien fishes of Suisun Marsh

American Fisheries Society (AFS) | July 29th, 1994

Overall fish abundance, abundance of introduced, native, and seasonal fish groups, and species diversity declined over a 14‐year period in Suisun Marsh, a portion of th

Overall fish abundance, abundance of introduced, native, and seasonal fish groups, and species diversity declined over a 14‐year period in Suisun Marsh, a portion of the San Francisco Bay estuary, and were associated with decreases in freshwater outflow and increases in salinity. Fish groups showed different patterns of abundance; large fluctuations in introduced and seasonal fish groups contrasted with a steady decline in native fish. Native species were found more often in small, dead‐end sloughs, seasonal species were found in larger sloughs, and introduced species were found in both habitats. Fish assemblage structure was less predictable than in an earlier (and shorter) study of the same community. Mixed groups of native and introduced species with similar freshwater and seasonal needs reflected effects of drought and increasing water diversions from the estuary. Chameleon goby Tridentiger trigonocephalus and yellowfin goby Acanthogobius flavimanus, two introduced species, fluctuated greatly in abundance in recent years, whereas other species declined steadily. Changes in fish abundance in the marsh reflect estuary‐wide changes and suggest that environmental disturbances coupled with introduced species are altering fish communities and hastening native fish declines.

Changes in Evapotranspiration of Agricultural Crops in Kern County during the 2014-2015 Drought Years

University of California, Davis (UC Davis) | September 5th, 2017

The 2012-2015 drought in California has major impacts for agricultural water users in Kern County. Farmers shifted crop planting patterns and irrigation scheduling to min

The 2012-2015 drought in California has major impacts for agricultural water users in Kern County. Farmers shifted crop planting patterns and irrigation scheduling to minimize profit loss with water shortage. This report models the changes in crop evapotranspiration from 2011 to 2014 and 2015 using the remote-sensing-based METRIC model developed by the University of Idaho. Results show that rather than universal losses of acreage and productivity, farmers reduced acreage on annual crops while increasing acreage on low-water-use new orchards. Productivity increased on the annual crops that remained in production, perhaps due to fallowing less productive land. High-value crops such as citrus and grapes saw increases in both acreage and productivity. Remote-sensing-based evapotranspiration mapping provides an important tool to policymakers by providing field-based estimates of a wide range of farmer responses to drought including planting, fallowing, under-irrigation, and, if combined with productivity models, changes in revenue. 

Changes in Riparian Vegetation in the Southwestern United States: Historical Changes along the Mojave River, California

U.S. Geological Survey (USGS) | January 31st, 2001

Changes in the productivity of US West Coast fish stocks

Fisheries Research (Elsevier) | April 21st, 2023

The California Current ecosystem is highly dynamic at interannual to interdecadal time scales. Variability has been documented in pelagic and other fish species, but clim

The California Current ecosystem is highly dynamic at interannual to interdecadal time scales. Variability has been documented in pelagic and other fish species, but climate change may be altering the historical models of variation. This study investigates changes in productivity of 31 fish stocks in the California Current ecosystem. Productivity was measured from recent stock assessments, as the per-capita recruitment rate, estimated with a dynamic stock-recruitment model. Contrary to expectations, the dynamic stock-recruitment model fit better than the corresponding stationary model for only seven of the 31 stocks. There was little evidence of linear drift in productivity that might be expected to result from climate change. Climate variables improved forecast accuracy for a few stocks, but there was no common climate signal in productivity. One explanation of these results is that most of the west coast stocks are above their biomass levels for maximum sustainable yield, making them less susceptible to environmental variation. On the other hand, the dynamic recruitment models improved short-term forecasts for all stocks, which may be useful for quota setting. Finally, results for the subset of stocks with dynamic recruitment models could be used to establish dynamic biological reference points.

Changes in water consumption linked to heavy news media coverage of extreme climatic events

American Association for the Advancement of Science (AAAS) | October 25th, 2017

Public awareness of water- and drought-related issues is an important yet relatively unexplored component of water use behavior. To examine this relationship, w

Public awareness of water- and drought-related issues is an important yet relatively unexplored component of water use behavior. To examine this relationship, we first quantified news media coverage of drought in California from 2005 to 2015, a period with two distinct droughts; the later drought received unprecedentedly high media coverage, whereas the earlier drought did not, as the United States was experiencing an economic downturn coinciding with a historic presidential election. Comparing this coverage to Google search frequency confirmed that public attention followed news media trends. We then modeled single-family residential water consumption in 20 service areas in the San Francisco Bay Area during the same period using geospatially explicit data and including news media coverage as a covariate. Model outputs revealed the factors affecting water use for populations of varying demographics. Importantly, the models estimated that an increase of 100 drought-related articles in a bimonthly period was associated with an 11 to 18% reduction in water use. Then, we evaluated high-resolution water consumption data from smart meters, known as advanced metering infrastructure, in one of the previously modeled service areas to evaluate breakpoints in water use trends. Results demonstrated that whereas nonresidential commercial irrigation customers responded to changes in climate, single-family residential customers decreased water use at the fastest rate following heavy drought-related news media coverage. These results highlight the need for water resource planners and decision makers to further consider the importance of effective, internally and externally driven, public awareness and education in water demand behavior and management.

Changes in Winter Atmospheric Rivers along the North American West Coast in CMIP5 Climate Models

American Meteorological Society (AMS) | April 1st, 2014

Most extreme precipitation events that occur along the North American west coast are associated with winter atmospheric river (AR) events. Global climate models h

Most extreme precipitation events that occur along the North American west coast are associated with winter atmospheric river (AR) events. Global climate models have sufficient resolution to simulate synoptic features associated with AR events, such as high values of vertically integrated water vapor transport (IVT) approaching the coast. From phase 5 of the Coupled Model Intercomparison Project (CMIP5), 10 simulations are used to identify changes in ARs impacting the west coast of North America between historical (1970–99) and end-of-century (2070–99) runs, using representative concentration pathway (RCP) 8.5. The most extreme ARs are identified in both time periods by the 99th percentile of IVT days along a north–south transect offshore of the coast. Integrated water vapor (IWV) and IVT are predicted to increase, while lower- tropospheric winds change little. Winter mean precipitation along the west coast increases by 11%–18% [from 4% to 6% (8C)21], while precipitation on extreme IVT days increases by 15%–39% [from 5% to 19% (8C)21]. The frequency of IVT days above the historical 99th percentile threshold increases as much as 290% by the end of this century.

Changing Channels: Regional Information for Developing Multi-benefit Flood Control Channels at the Bay Interface

San Francisco Estuary Institute (SFEI) | May 26th, 2017

Over the past 200 years, many of the channels that drain to San Francisco Bay have been modified for land reclamation and flood management. The local agencies that overse

Over the past 200 years, many of the channels that drain to San Francisco Bay have been modified for land reclamation and flood management. The local agencies that oversee these channels are seeking new management approaches that provide multiple benefits and promote landscape resilience. This includes channel redesign to improve natural sediment transport to downstream bayland habitats and beneficial re-use of dredged sediment for building and sustaining baylands as sea level continues to rise under a changing climate. Flood Control 2.0 is a regional project that was created to help develop innovative approaches for integrating habitat improvement and resilience into flood risk management at the Bay interface. Through a series of technical, economic, and regulatory analyses, the project addresses some of the major elements associated with multi-benefit channel design and management at the Bay interface and provides critical information that can be used by the management and restoration communities to develop long-term solutions that benefit people and wildlife. This Flood Control 2.0 report provides a regional analysis of morphologic change and sediment dynamics in flood control channels at the Bay interface, and multi-benefit management concepts aimed at bringing habitat restoration into flood risk management. The findings presented here are built on a synthesis of historical and contemporary data that included input from Flood Control 2.0 project scientists, project partners, and science advisors. The results and recommendations, summarized below, will help operationalize many of the recommendations put forth in the Baylands Ecosystem Habitat Goals Science Update (Goals Project 2015) and support better alignment of management and restoration communities on multi-benefit bayland management approaches.

Changing Channels: Regional Information for Developing Multi-benefit Flood Control Channels at the Bay Interface

San Francisco Estuary Institute (SFEI) | April 3rd, 2017

Over the past 200 years, many of the channels that drain to San Francisco Bay have been modified for land reclamation and flood management. The local agencies that overse

Over the past 200 years, many of the channels that drain to San Francisco Bay have been modified for land reclamation and flood management. The local agencies that oversee these channels are seeking new management approaches that provide multiple benefits and promote landscape resilience. This includes channel redesign to improve natural sediment transport to downstream bayland habitats and beneficial re-use of dredged sediment for building and sustaining baylands as sea level continues to rise under a changing climate. Flood Control 2.0 is a regional project that was created to help develop innovative approaches for integrating habitat improvement and resilience into flood risk management at the Bay interface. Through a series of technical, economic, and regulatory analyses, the project addresses some of the major elements associated with multi-benefit channel design and management at the Bay interface and provides critical information that can be used by the management and restoration communities to develop long-term solutions that benefit people and wildlife. This Flood Control 2.0 report provides a regional analysis of morphologic change and sediment dynamics in flood control channels at the Bay interface, and multi-benefit management concepts aimed at bringing habitat restoration into flood risk management. The findings presented here are built on a synthesis of historical and contemporary data that included input from Flood Control 2.0 project scientists, project partners, and science advisors. The results and recommendations, summarized below, will help operationalize many of the recommendations put forth in the Baylands Ecosystem Habitat Goals Science Update (Goals Project 2015) and support better alignment of management and restoration communities on multi-benefit bayland management approaches.