North Coast

Hydrologic and Geochemical Characterization of the Santa Rosa Plain Watershed, Sonoma County, California

U.S. Geological Survey (USGS) | July 9th, 2013

The Santa Rosa Plain is home to approximately half of the population of Sonoma County, California, and faces growth in population and demand for water. Water managers are

The Santa Rosa Plain is home to approximately half of the population of Sonoma County, California, and faces growth in population and demand for water. Water managers are confronted with the challenge of meeting the increasing water demand with a combination of water sources, including local groundwater, whose future availability could be uncertain. To meet this challenge, water managers are seeking to acquire the knowledge and tools needed to understand the likely effects of future groundwater development in the Santa Rosa Plain and to identify efficient strategies for surface- and groundwater management that will ensure the long-term viability of the water supply. The U.S. Geological Survey, in cooperation with the Sonoma County Water Agency and other stakeholders in the area (cities of Cotati, Rohnert Park, Santa Rosa, and Sebastopol, town of Windsor, Cal-American Water Company, and the County of Sonoma), undertook this study to characterize the hydrology of the Santa Rosa Plain and to develop tools to better understand and manage the groundwater system. The objectives of the study are: (1) to develop an updated assessment of the hydrogeology and geochemistry of the Santa Rosa Plain; (2) to develop a fully coupled surface-water and groundwater-flow model for the Santa Rosa Plain watershed; and (3) to evaluate the potential hydrologic effects of alternative groundwater-management strategies for the basin. The purpose of this report is to describe the surface-water and groundwater hydrology, hydrogeology, and water-quality characteristics of the Santa Rosa Plain watershed and to develop a conceptual model of the hydrologic system in support of the first objective. The results from completing the second and third objectives will be described in a separate report.

Hydrology, Ecology, and Fishes of the Klamath River Basin (2008)

National Academy of Sciences (NAS) | January 1st, 2008

The Klamath River basin, which spans parts of southern Oregon and northern California, has been the focus of a prominent conflict over competing uses for water. Manag

The Klamath River basin, which spans parts of southern Oregon and northern California, has been the focus of a prominent conflict over competing uses for water. Management actions to protect threatened and endangered fish species in the basin have left less water available for irrigation in dry years and heightened tensions among farmers and other stakeholders including commercial fishermen, Native Americans, conservationists, hunters, anglers, and hydropower producers. This National Research Council report assesses two recent studies that evaluate various aspects of flows in the Klamath basin: (1) the Instream Flow Phase II study (IFS), conducted by Utah State University, and (2) the Natural Flow of the Upper Klamath Basin study (NFS), conducted by the U.S. Bureau of Reclamation (USBR). The report concludes that both studies offer important new information but do not provide enough information for detailed management of flows in the Klamath River, and it offers many suggestions for improving the studies. The report recommends that a comprehensive analysis of the many individual studies of the Klamath river basin be conducted so that a big picture perspective of the entire basin and research and management needs can emerge. Key Messages If these conclusions were borne out by studies incorporating experimental flows and monitored responses, managers would be able to have greater confidence that decisions to increase flows would have a beneficial effect on anadromous fishes in the lower river The Instream Flow Study Phase II did not include important water-quality attributes, such as dissolved oxygen levels, nutrient loadings, contaminants, and sediment concentrations, although each has important implications for the vitality of the fish populations of the Klamath River. The Natural Flow Study and the Instream Flow Study Phase II were major science and engineering investigations, but the linkage of one to the other was only partially achieved. The Natural Flow Study was seriously compromised by several fundamental issues, including its choice of a basic approach for understanding natural flows, choices of the models for calculations, and serious omissions of factors likely to influence river flows at the Iron Gate Dam gauge site. The basin and its biota have changed so much in the past century that the implications for the fishes of restoring natural flows are not clear. The committee concluded that the Natural Flow Study includes calculated flows that are at best first approximations to useful estimates of such flows. The committee found important shortcomings in the Instream Flow Study Phase II and its use of various models and data. Two major shortcomings use of monthly data and lack of tributary analyses are so severe that that they should be addressed before decision makers can use the outputs of the study to establish precise flow regimes with confidence. The most important outcome of the Instream Flow Study was that it indicated that increases in existing flows downstream from Iron Gate Dam probably would benefit fish populations through improved physical habitat associated with more water and through reduced water temperatures. There was a lack of a thorough assessment of the relationship between flow-data time series and the behavior of different species and life stages and the population dynamics of coho and Chinook salmon When the science needs for the basin are better characterized, the individual studies necessary to create a sound science-based body of knowledge for decision makers and managers will be more easily identified. current flow regime. These are improvements in flow because they include intra- and inter-annual variations and probably will enhance Chinook salmon growth and young-of-the-year production. is not possible to know how well the recommendations apply to any one species or to all the species as a whole. Indeed, most of the information was from Chinook salmon, which suggests that confidence in its applicability to that species would be greater than to other species. of the representativeness of the reaches used for detailed study, and the statistical approach to analyze the calculated set of instream flows did not use normalized data and did not have provisions for identifying serial autocorrelations.

Hydropower capacity factors trending down in the United States

Nature Portfolio (Springer Nature) | June 27th, 2024

Hyper-Salinity Toxicity Thresholds for Nine California Ocean Plan Toxicity Test Protocols

California State Water Resources Control Board (SWRCB) | July 1st, 2012

A growing number of coastal cities in California are exploring the potential for ocean desalination as a means to augment freshwater supplies. There are currently a numbe

A growing number of coastal cities in California are exploring the potential for ocean desalination as a means to augment freshwater supplies. There are currently a number of desalination facilities proposed or operating in California. The process of desalination most commonly utilizes reverse osmosis (RO) to remove salts from groundwater, reclaimed water, and seawater. This process results in production of hypersaline reject brine. This reject brine may be discharged into the marine environment, sometimes in combination with discharge from a sewage treatment plant or power plant effluent. Typical RO reject brine produced using 100% seawater can have approximately twice the original salt content of seawater. In order to ensure that brine discharges do not pose risk to coastal receiving waters, it is anticipated that desalination plants will be required to monitor effluent toxicity. Monitoring requirements will likely include testing for effluent toxicity using some combination of the short-term chronic toxicity test protocols listed in the 2009 California Ocean Plan (SWRCB, 2009). While the tests listed in the Ocean Plan have been the subject of ongoing research, no comprehensive studies of the effects of hyper-salinity have been conducted with all seven toxicity test organisms (nine protocols when including sand dollar and urchin fertilization endpoints). The results from these tests will allow determination of the toxicity of hypersaline brine in the absence of any additional toxic constituents that may be produced during the desalination process. These results provide resource managers with background information to facilitate interpretation of toxicity test results from desalination plant effluent testing and permitting of desalination facilities. The results will also be used in the development of an amendment to the California Ocean Plan that addresses impacts to marine life from intakes and discharges from desalination facilities.

Identifying organic contaminants at trespass cannabis grows on federal land in California, USA

Elsevier | September 25th, 2025

Despite the legalization of recreational cannabis in California, USA, illegal cannabis cultivation remains pervasive, partly through the establishment of illegal cult

Despite the legalization of recreational cannabis in California, USA, illegal cannabis cultivation remains pervasive, partly through the establishment of illegal cultivation on public lands (trespass grows). These operations often illegally divert water for irrigation and perform unauthorized applications of chemical fertilizers and pesticides. This work investigates a broad suite of these chemicals, focusing on their persistence in topsoil and presence in water and bed sediment in adjacent streams. Quantitative analyses of pesticides were conducted (183 compounds in water; 176 in topsoil/bed sediment), supplemented by qualitative nontargeted screening at three trespass grows that had no active cultivation for 8 months to 2 years. Targeted multi-residue analysis of topsoil detected the insecticides bifenthrin, cyfluthrin, malathion and imidacloprid (with concentrations up to 38 ng/g dry weight, d.w.), and the fungicides fluopyram, myclobutanil, and triadimefon (concentrations up to 8.1 ng/g d.w.). No pesticides were detected in the companion water or streambed sediment samples from adjacent streams. In addition, no water samples were found to have measurable estrogenic activity. Nontargeted screening uncovered additional pesticides (i.e., spiromesifen, trinexapac) in the topsoil and cannabis-related compounds (i.e., cannabidol, delta9-tetrahydrocannabinol) in both topsoil and streambed sediment suggesting the likelihood of offsite transport of cannabis related compounds. Phthalate plasticizers, rubber-related compounds, pharmaceuticals and personal care product chemicals were detected in topsoil, water, and streambed sediment and may be related to extensive irrigation infrastructure installed at these trespass grows. This work begins to establish a contaminant profile associated with illegal cannabis growing activities, providing a foundation for future research focused on their potential ecological impacts.

Identifying the Amount of Wastewater that is Available and Feasible to Recycle in California

Water Research Foundation (WRF) | July 24th, 2023

Identifying the location and population served by domestic wells in California

Journal of Hydrology: Regional Studies (Elsevier) | November 17th, 2014

Study region: California, USA. Study focus: Identification of groundwater use is an important stepin the regional-scale assessment of groundwater quality. In Califo

Study region: California, USA. Study focus: Identification of groundwater use is an important stepin the regional-scale assessment of groundwater quality. In California, 1990 US Census data indicate that domestic wells provide drinking-water to about 1.2 million people. However, the location of these domestic well users of groundwater is poorly identified because the census tracts can be quite large (up to 20,000 km2). The purposes of this paper are to present methods used for (1) estimating the location of domestic wells, (2) estimating the location of households using domes-tic well water; and (3) identifying where in California groundwater isan important source of domestic drinking supply.New hydrological insights for the region: Aggregating the results indicates that three hydrogeologic provinces contain nearly 80% of all domestic wells and also have the highest density of domestic well-users: Central Valley (31.6%), Sierra Nevada (31.5%), and NorthernCoast Ranges (16.6%). Results were also aggregated into groundwater basins and highland areas, collectively called Groundwater Units(GUs). Twenty-eight of the 938 GUs contain more than 50% of the total population served by domestic wells, 70 GUs contain more than 75%, and 150 GUs contain 90%. The 28 GUs are mostly located in the eastern and southern San Joaquin Valley (11), the Sacramento Valley (7), and the western foothills of the Sierra Nevada province (5). Using the information presented in this research along with other information about domestic-well use, the US Geological Survey has begun sampling high-use GUs for the Shallow Aquifer Assessment component of the Groundwater Ambient Assessment (GAMA) program.

Impact of current and warmer climate conditions on snow cover loss in burned forests

American Association for the Advancement of Science (AAAS) | September 17th, 2025

Wildfires are increasingly burning in snow-dominated watersheds and can alter snowmelt dynamics. However, the spatial variability of snow cover loss in burned forests has

Wildfires are increasingly burning in snow-dominated watersheds and can alter snowmelt dynamics. However, the spatial variability of snow cover loss in burned forests has been under characterized. Here, we use remotely sensed snow data to show that, under average winter conditions, snow melts earlier in the first year postfire in 99% of the snow zone. Postfire snow cover loss is more extreme in relatively low-elevation, warm environments compared to that in high-elevation, cold regions. Under +2°C of warming, 73% of the snow zone would experience more extreme earlier postfire snowmelt compared to historically average conditions. Regions with the largest shift earlier in postfire snowmelt timing under average climate conditions also have the largest shift earlier in postfire snowmelt under +2°C warming. The spatial variability in postfire snowmelt timing and exacerbated impact in projected warmer winters affect ecosystem water availability, snow albedo feedbacks, and snowmelt runoff forecasting essential to water resource management.

Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming

Wiley | February 21st, 2013

Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, a

Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms' responses and corresponding levels of certainty is necessary to forecast the ecological effects. Here, we perform the most comprehensive meta‐analysis to date by synthesizing the results of 228 studies examining biological responses to ocean acidification. The results reveal decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups, suggesting there is some predictable trait‐based variation in sensitivity, despite the investigation of approximately 100 new species in recent research. The results also reveal an enhanced sensitivity of mollusk larvae, but suggest that an enhanced sensitivity of early life history stages is not universal across all taxonomic groups. In addition, the variability in species' responses is enhanced when they are exposed to acidification in multi‐species assemblages, suggesting that it is important to consider indirect effects and exercise caution when forecasting abundance patterns from single‐species laboratory experiments. Furthermore, the results suggest that other factors, such as nutritional status or source population, could cause substantial variation in organisms' responses. Last, the results highlight a trend towards enhanced sensitivity to acidification when taxa are concurrently exposed to elevated seawater temperature.

Implementing Climate-Smart Conservation

Public Policy Institute of California (PPIC) | March 4th, 2025

In our first report, Climate-Smart Tools to Protect California’s Freshwater Biodiversity (Sommer et al. 2024), we reviewed a broad suite of tools available to a

In our first report, Climate-Smart Tools to Protect California’s Freshwater Biodiversity (Sommer et al. 2024), we reviewed a broad suite of tools available to address the urgent problem of safeguarding California’s freshwater biodiversity in the changing climate. This toolbox includes some familiar approaches—such as various ways to improve freshwater habitat—as well as approaches that may be less familiar, more experimental, and more controversial. We also recommended the adoption of a climate-smart conservation planning process, involving a broad range of stakeholders, to prioritize the selection of tools within watersheds and to adaptively implement those tools. In this follow-up report, we explore the feasibility of implementing these tools and climate-smart planning in light of legal, policy, and institutional factors.2 Our analysis draws on an extensive review of the legal literature on ecosystem and protected species management, as well as interviews and small workshops with a wide-ranging set of 45 experts from all over the state. These experts are working on the frontlines of ecosystem policy and management; they include state and federal regulators, members of the environmental conservation community, legal professionals, and representatives of many entities involved in water and land management.