San Joaquin River Restoration Program

San Joaquin River Restoration Program | December 13th, 2007

San Joaquin River Restoration Settlement

Congressional Research Service (CRS) | November 9th, 2007

Historically, Central California’s San Joaquin River supported large Chinook salmon populations. Since the Bureau of Reclamation’s Friant Dam on the San Joaquin River

Historically, Central California’s San Joaquin River supported large Chinook salmon populations. Since the Bureau of Reclamation’s Friant Dam on the San Joaquin River became fully operational in the 1940s, much of the river’s water has been diverted for off-stream agricultural uses. As a result, approximately 60 miles of the river bed is dry in most years. Thus, the river no longer supports Chinook salmon populations in its upper reaches. In 1988, a coalition of conservation and fishing groups sued Reclamation (Natural Resources Defense Council v. Rodgers). A U.S. District Court judge has ruled that operation of Friant Dam violates state law because of its destruction of downstream fisheries. Faced with mounting legal fees, uncertainty, and the possibility of dramatic cuts to water diversions, parties negotiated a settlement instead of proceeding to trial. In September 2006, an agreement, commonly called the Settlement, was reached. It calls for new releases of water from Friant Dam to restore fisheries, as well as for efforts to mitigate reductions in off-stream deliveries lost to restoration flows. Congressional authorization and appropriations are required for full Settlement implementation. Legislation based on the Settlement (H.R. 4074, H.R. 24 and S. 27) is pending. Related bills have also been introduced. A key legislative issue is how to finance the Settlement, specifically how to resolve congressional pay-as-you-go (PAYGO) issues. Other challenges are how to achieve the Settlement’s dual goals of fisheries restoration and water management, and how to address concerns of stakeholders not party to the Settlement, without disrupting the negotiated agreement. The amount of water projected for restoration flows and the volume of reduced Friant water deliveries are related, but the relationship would not necessarily be one-for-one. Available estimates for total annual Friant water supplies (including both contract and temporary water) are, on average, 15% to 16% less under the Settlement than under current operations; but such estimates do not account for improvements in water management that might reduce the impact on water users. For three-quarters of water contractors, the reduction would represent a reduction in one of their available sources of water. The impacts of such reductions will vary by contractor depending on the firmness of existing surface water supplies and the reliability of groundwater supplies. How to offset the decrease and who would pay for investments in other water sources and improved efficiency has not been determined. Although the region may benefit from increased recreational expenditures and investment in river restoration activities under the Settlement, studies suggest its largest and mostly negative economic impact would be on the agriculture industry, at least in the short term. In addition, downsteam interests not party to the Settlement have been concerned about increased flooding, groundwater infiltration, and competition with existing federal financial commitments. Nearby communities fear harm to groundwater quantity and quality. Some of these concerns have been addressed in the legislation, but some remain. On the other hand, some communities and interests believe restoration will bring other benefits to the river, such as improved surface water quality in lower San Joaquin River reaches. Ultimate Settlement costs and benefits are very difficult to predict.

San Luis Obispo Coastkeeper v. Santa Maria Valley Water Conservation District

United States District Court, Central District of California | September 23rd, 2022

Scattered tree death contributes to substantial forest loss in California

Nature Portfolio (Springer Nature) | January 20th, 2024

In recent years, large-scale tree mortality events linked to global change have occurred around the world. Current forest monitoring methods are crucial for identifying m

In recent years, large-scale tree mortality events linked to global change have occurred around the world. Current forest monitoring methods are crucial for identifying mortality hotspots, but systematic assessments of isolated or scattered dead trees over large areas are needed to reduce uncertainty on the actual extent of tree mortality. Here, we mapped individual dead trees in California using sub-meter resolution aerial photographs from 2020 and deep learning-based dead tree detection. We identified 91.4 million dead trees over 27.8 million hectares of vegetated areas (16.7-24.7% underestimation bias when compared to field data). Among these, a total of 19.5 million dead trees appeared isolated, and 60% of all dead trees occurred in small groups ( ≤ 3 dead trees within a 30 × 30 m grid), which is largely undetected by other state-level monitoring methods. The widespread mortality of individual trees impacts the carbon budget and sequestration capacity of California forests and can be considered a threat to forest health and a fuel source for future wildfires.

Scenarios of climate adaptation potential on protected working lands from management of soils

Environmental Research Letters (IOP) | September 30th, 2019

Management of protected lands may enhance ecosystem services that conservation programs were designed to protect. Practices that build soil organic matter on agri

Management of protected lands may enhance ecosystem services that conservation programs were designed to protect. Practices that build soil organic matter on agricultural lands also increase soil water holding capacity, potentially reducing climatic water deficit (CWD), increasing actual evapotranspiration (AET) and increasing groundwater recharge (RCH). We developed nine spatially-explicit land use and conservation scenarios (2001–2100) in the LUCAS land use change model to address two questions for California working lands (cropland and rangeland): How does land use change limit opportunities to manage soils for hydrologic climate adaptation benefits? To what extent and where can soil management practices increase climate adaptation on protected working lands? Hydrologic benefits [Σ(ΔCWD, ΔAET, ΔRCH)] due to soil management were simulated in the Basin Characterization Model (a state-wide water balance model) for two Representative Concentration Pathway 8.5 climate models. LUCAS simulated land conversion and new conservation easements with potential for maximum hydrologic benefits. Climate drove differences in lost potential for water benefits due to urbanization (33.9–87.6 m3 × 106) in 2050. Conflict between development pressure and potential hydrologic benefits occurred most in Santa Clara County in the San Francisco Bay Area and Shasta County in Northern Sacramento Valley. Hydrologic benefits on easements were similar in magnitude to losses from development. Water savings from management of California Land Conservation (a.k.a. Williamson) Act contract lands were an order of magnitude greater, totaling over 460 m3 × 106 annually in a drier climate by 2050. Few counties provide most benefits because of soil properties, climate and land area protected. The increase in hydrologic benefits varies by agricultural practice and adoption rate, land use type and configuration, and terms of conservation agreements. The effectiveness of programs designed to improve climate adaptation at county to state scales will likely increase by taking this variability into consideration.

Science be Dammed: How Ignoring Inconvenient Science Drained the Colorado River

University of Arizona Press | November 26th, 2019

Science Be Dammed is an alarming reminder of the high stakes in the management—and perils in the mismanagement—of water in the western United States.  It seems decep

Science Be Dammed is an alarming reminder of the high stakes in the management—and perils in the mismanagement—of water in the western United States.  It seems deceptively simple: even when clear evidence was available that the Colorado River could not sustain ambitious dreaming and planning by decision-makers throughout the twentieth century, river planners and political operatives irresponsibly made the least sustainable and most dangerous long-term decisions. Arguing that the science of the early twentieth century can shed new light on the mistakes at the heart of the over-allocation of the Colorado River, authors Eric Kuhn and John Fleck delve into rarely reported early studies, showing that scientists warned as early as the 1920s that there was not enough water for the farms and cities boosters wanted to build. Contrary to a common myth that the authors of the Colorado River Compact did the best they could with limited information, Kuhn and Fleck show that development boosters selectively chose the information needed to support their dreams, ignoring inconvenient science that suggested a more cautious approach. Today water managers are struggling to come to terms with the mistakes of the past. Focused on both science and policy, Kuhn and Fleck unravel the tangled web that has constructed the current crisis. With key decisions being made now, including negotiations for rules governing how the Colorado River water will be used after 2026, Science Be Dammed offers a clear-eyed path forward by looking back. Understanding how mistakes were made is crucial to understanding our contemporary problems. Science Be Dammed offers important lessons in the age of climate change about the necessity of seeking out the best science to support the decisions we make.

Scientist and Stakeholder Views on the Delta Ecosystem

Public Policy Institute of California (PPIC) | April 22nd, 2013

There is broad scientific recognition that a wide range of ecosystem stressors are responsible for the declines in native fish populations in the Sacramento–San Joaquin

There is broad scientific recognition that a wide range of ecosystem stressors are responsible for the declines in native fish populations in the Sacramento–San Joaquin Delta. But science and policymaking have been at odds about the roles of different stressors and the potential of various management actions to improve ecosystem health. In the summer of 2012, PPIC conducted two confidential surveys on the impact of ecosystem stressors: one sought input from scientific experts and the other focused on stakeholders and policymakers. This report analyzes the results and examines the implications of both surveys.

Scott Valley Integrated Hydrologic Model: Data Collection, Analysis, and Water Budget Final Report

University of California, Davis (UC Davis) | November 14th, 2017

The Scott Valley is an agricultural groundwater basin in Northern California, within the Scott River watershed and part of the much larger Klamath Basin watershed straddl

The Scott Valley is an agricultural groundwater basin in Northern California, within the Scott River watershed and part of the much larger Klamath Basin watershed straddling the California-Oregon border. The Scott River provides important habitat for salmonid fish, including spawning and rearing habitat for coho and fall-run Chinook salmon and steelhead trout. Sufficient flows at adequately low temperatures during summer, for rearing, and fall, for spawning, are critical for healthy fish habitat in the mainstem and tributaries. This report presents the data assembled and the methods used for data analysis and data modeling to prepare the Scott Valley Integrated Hydrologic Model Version 2, which is currently under development. The report includes precipitation data analysis, streamflow data analysis and modeling, geology and groundwater data review and analysis, evapotranspiration and soils data analysis, and preparation of relevant watershed, land use, topography, and irrigation data. The data collection and analysis efforts culminate in the development of a spatio-temporally distributed soil water budget model for the Scott Valley. The soil water budget model is used to determine spatially and temporally varying groundwater pumping rates, surface water diversion rates, and groundwater recharge across the groundwater basin. The spatial resolution of the soil water budget model is by individual fields (land use polygons). Temporal discretization is in daily time steps for the period from October 1, 1990 to September 30, 2011. This period includes several dry years, average years, and wet year periods. Methods and results of the soil water budget model are presented in this report. This report represents the next step toward a better understanding of the interactions between groundwater, surface water, land-use, and agricultural practices with a specific focus on the seasonal impacts of groundwater pumping on streamflow during critical low flow periods. The work presented here relies on an extensive data collection facilitated by the voluntary and active collaboration of communities, landowners, the Scott River Watershed Council (SRWC), the Siskiyou Resource Conservation District (SRCD), and the Scott Valley Groundwater Advisory Committee (GWAC) which has been appointed by the Board of Supervisors in January 2011, meeting monthly since April 2011 and advising UC Davis on its data collection and modeling efforts. In the data analysis and during the model development, numerous assumptions have been made as is common in building a conceptual and numerical integrated hydrologic model. Models cannot represent the complexity of the real system, but are an effort to capture salient hydrologic features with sufficient accuracy to develop modeling results that are useful for a better understanding of the watershed dynamics and water balance.

Seasonal and Long-Term Clarity Trend Assessment of Lake Tahoe, California–Nevada

U.S. Geological Survey (USGS) | July 20th, 2022

The clarity of Lake Tahoe, observed using a Secchi disk on a regular basis since the late 1960s, continues to be a sentinel metric of lake health. Water clarity is influe

The clarity of Lake Tahoe, observed using a Secchi disk on a regular basis since the late 1960s, continues to be a sentinel metric of lake health. Water clarity is influenced by physical and biological processes and has declined in the five decades of monitoring, revealing differences between summer (June–September) and winter (December–March). This document summarizes key findings of a study of Lake Tahoe water clarity, including long-term variability and the relative importance of several influencing variables and processes. This study, prepared in cooperation with the Nevada Division of Environmental Protection, focused on (1) an apparent divergence in clarity trends between summer and winter periods, (2) observed changes in in-lake physical and ecological variables that may influence or control seasonal and annual clarity trends, and (3) five research hypotheses regarding lake clarity that were developed by Lake Tahoe management agencies. Previously collected data were used to complete this study. Trend analysis confirmed that winter clarity stabilized (that is, there is no longer a statistically significant trend up or down) during the last 20 years. Evaluation of clarity for selected months in the 50-year Secchi disk clarity dataset showed that only two summer months, July and August, had statistically significant decreases in clarity from 2000–19. Different subsets of available data were analyzed to reveal the presence or absences of trends for each season, decade, and month. Five hypotheses related to lake clarity were part of the study described by this report. Hypothesis 1 stated that clarity is controlled predominantly by the distribution and volumetric density of fine particles in suspension. This hypothesis was studied using available data describing in-lake fine (0–20 micrometers) particles from 2008–19. Water clarity was negatively correlated with in-lake particle abundance, with particles in the 1.0-4.6 μm range having the greatest effect, consistent with light-scattering theory. Estimated abundances of diatoms of the genus Cyclotella also were found to be negatively correlated with clarity. Data limitations precluded a complete investigation of hypothesis 2, which stated that the observed improvements in winter water clarity are a response to decreasing fine suspended-sediment concentrations in the lake resulting from load reductions from upland sources in and near urbanized areas. Data describing fine-sediment loading from urban areas to the lake were only available since 2014, and only once or twice per month. A slight, statistically significant, negative correlation was identified between urban fine-particle loading and monthly lake clarity with a 4-month lag. Particle abundance in monitored streams is highly correlated with simultaneous particle abundance in the lake.

SediMatch Factsheet

San Francisco Estuary Institute (SFEI) | June 1st, 2018

 SediMatch is a collaborative program of the San Francisco Bay Joint Venture (SFBJV), the San Francisco Bay Conservation and Development Commission (BCDC), the San Franc

 SediMatch is a collaborative program of the San Francisco Bay Joint Venture (SFBJV), the San Francisco Bay Conservation and Development Commission (BCDC), the San Francisco Estuary Institute (SFEI), the San Francisco Estuary Partnership (SFEP), and others to bring together the wetland habitat restoration, flood control, and dredging communities to discuss challenges and find mutually beneficial strategies to increase reuse of dredged sediment at habitat restoration sites.