North Coast

Delta Adapts: Creating a Climate Resilient Future

Delta Stewardship Council (DSC) | June 25th, 2025

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consider

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consideration to achieve that mission in future decades. To respond to the challenge of climate adaptation,the Council developed this initiative, Delta Adapts: Creating a Climate Resilient Future (Delta Adapts). Climate change must be considered to attain the state’s coequal goals, as established by the 2009 Delta Reform Act: securing a reliable water supply for California, protecting and restoring the ecosystem and wildlife it supports, and enhancing the Delta as a unique place, with its community, tribal, and agricultural heritage. The Council adopted the Delta Plan, which has regulatory policies that protect land for restoration and agriculture, help manage flood risk, and improve water supply reliability. The Delta Plan directs the Council to guide and regulate actions of the 200+ state and local agencies in the Delta to ensure they support statewide water supply reliability and Delta ecosystem restoration.

Design and methods of the California stream quality assessment (CSQA), 2017

U.S. Geological Survey (USGS) | April 21st, 2020

During 2017, as part of the National Water-Quality Assessment Project, the U.S. Geological Survey conducted the California Stream Quality Assessment to investigate the qu

During 2017, as part of the National Water-Quality Assessment Project, the U.S. Geological Survey conducted the California Stream Quality Assessment to investigate the quality of streams in the Central California Foothills and Coastal Mountains ecoregion, United States. The goal of the California Stream Quality Assessment study was to assess the health of wadeable streams in the region by characterizing multiple water-quality factors that are stressors to aquatic biota and by evaluating the relation between these stressors and biological indicators of stream health. Urbanization, agriculture, and modifications to streamflow are anthropogenic changes that affect water quality in the region; consequently, the study design primarily targeted sites and specific stressors associated with these activities. For the study, 85 stream sites were selected to represent the types and intensity of land use in the watershed; categories of site types were undeveloped, urban (low, medium, high), agriculture (low, high), and mixed (urban and agriculture). Most sites (about 70 percent) represent a gradient of urbanization from undeveloped to 99-percent urbanized. At most of the sites, streamgages or pressure transducers were used to monitor stream discharge and stage, as well as temperature. Water-quality samples were collected routinely at all sites and were analyzed for major ions, organic contaminants, nutrients, and suspended sediment. Sampling frequency varied on the basis of site type and location. Discrete water samples were collected weekly and generally 6 times per site, except for 11 undeveloped sites that were sampled only 4 times (during the last 4 weeks). Water sampling began at sites in the southern part of the study on March 13, 2017, and at sites in the northern part of the study on April 3, 2017. Passive samplers were deployed at most sites for measurement of polar organic contaminants (pesticides and pharmaceuticals). In May 2017, coincident with completion of water-quality sampling, an ecological survey was conducted at each site to assess benthic algal and macroinvertebrate communities and instream habitat. During the ecological surveys, a single composite streambed-sediment sample was collected for chemical analysis and toxicity testing. In addition, a few focused studies were done at subsets of sites, namely, measuring pesticides using small-volume automated samplers, measuring pesticides in biofilms, and sampling suspended sediments using passive samplers. This report describes the various study components and methods of the California Stream Quality Assessment, including measurements of water quality, sediment chemistry, habitat assessments, and ecological surveys, as well as procedures for sample analysis, quality assurance and quality control, and data management.

Ditching Our Innocence: The Clean Water Act in the Age of the Anthropocene

Lewis & Clark College | May 10th, 2018

Humanity has entered the Age of the Anthropocene, a geologic era marked by the emergence of human activity as the single most dominant influence on Earth’s environment.

Humanity has entered the Age of the Anthropocene, a geologic era marked by the emergence of human activity as the single most dominant influence on Earth’s environment. Every ecosystem shows signs of anthropogenic influence, and the environments we experience everyday are often shaped almost entirely by human actions and decisions. The new discipline of reconciliation ecology recognizes this reality and suggests that we must manage the new habitats we create in order to protect species diversity and ecosystem services. But the 2015 rule defining the jurisdiction of the Clean Water Act explicitly excludes many manmade environments, including many artificial lakes, farm ponds, reflecting pools, and most ditches, treating these landscape features as faux nature somehow unworthy of protection. This treatment is a marked departure from past Environmental Protection Agency and U.S. Army Corps of Engineers practices, which allowed for consideration of such places on a case-by-case basis. This departure finds no support in the Supreme Court precedent leading up to the new rule and seems to be based entirely on a shortsighted view of these places as somehow unimportant to protecting the waters of the United States. Based on the law and science surrounding ditches, we conclude that such places merit protection under the Clean Water Act.

Downscaling global ocean climate models improves estimates of exposure regimes in coastal environments

Nature Portfolio (Springer Nature) | August 26th, 2020

Climate change is expected to warm, deoxygenate, and acidify ocean waters. Global climate models (GCMs) predict future conditions at large spatial scales, and these pred

Climate change is expected to warm, deoxygenate, and acidify ocean waters. Global climate models (GCMs) predict future conditions at large spatial scales, and these predictions are then often used to parameterize laboratory experiments designed to assess biological and ecological responses to future change. However, nearshore ecosystems are affected by a range of physical processes such as tides, local winds, and surface and internal waves, causing local variability in conditions that often exceeds global climate models. Predictions of future climatic conditions at local scales, the most relevant to ecological responses, are largely lacking. To fill this critical gap, we developed a 2D implementation of the Regional Ocean Modeling System (ROMS) to downscale global climate predictions across all Representative Concentration Pathway (RCP) scenarios to smaller spatial scales, in this case the scale of a temperate reef in the northeastern Pacific. To assess the potential biological impacts of local climate variability, we then used the results from different climate scenarios to estimate how climate change may affect the survival, growth, and fertilization of a representative marine benthic invertebrate, the red abalone Haliotis rufescens, to a highly varying multi-stressor environment. We found that high frequency variability in temperature, dissolved oxygen (DO), and pH increases as pCO2 increases in the atmosphere. Extreme temperature and pH conditions are generally not expected until RCP 4.5 or greater, while frequent exposure to low DO is already occurring. In the nearshore environment simulation, strong RCP scenarios can affect red abalone growth as well as reduce fertilization during extreme conditions when compared to global scale simulations.

Drinking Water Notification Levels and Response Levels: An Overview

California State Water Resources Control Board (SWRCB) | February 6th, 2020

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of H

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of Health Services, CDHS, established health-based advisory levels, called “notification levels” (referred to as “action levels" through 2004), as needed since the early 1980s. These have been used to provide information to public water systems and others about certain non-regulated chemicals in drinking water that lack maximum contaminant levels (MCLs).  When chemicals are found at concentrations greater than these levels, certain requirement and recommendations apply.  Generally, notification levels have been established in response to actual contamination of drinking water supplies, e.g., perchlorate, which now has an MCL. However, notification levels for a number of chemicals were established in anticipation of possible contamination, such as from a hazardous waste site containing many pesticides (in the 1980s), or from a Superfund site (in the 2000s).  Chemicals for which notification levels are established may eventually be regulated by MCLs (through a formal regulatory process), depending on the extent of contamination, the levels observed, and the risk to human health. Most, however, have not proceeded to MCLs. Once established, a notification level generally stays in place, unless it is replaced by an MCL.On occasion, though, we have revised the numeric value of an individualnotification level to reflect new risk assessment information on the particularchemical. For some of the chemicals that had advisory levels established early on, if noMCL was adopted and the need for the notification level had passed, the advisory levelwas archived. Archived advisory levels may nevertheless be updated to reflect any newrisk information that may become available, and may be used as notification levels ifneeded. To date, of the 93 chemicals for which notification levels have been established; 40 now have MCLs. Of the remaining 53 chemicals, 29 are chemicals with current notification levels. 24 are chemicals with archived advisory levels (AALs). Note that following adoption of an MCL, the notification level is no longer used. For more about AALs and notification levels, go to: http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NotificationLevels.shtml. 

Drought and Groundwater Sustainability in California’s Farming Regions

Public Policy Institute of California (PPIC) | June 25th, 2024

Drought less predictable under declining future snowpack

Nature Portfolio (Springer Nature) | April 20th, 2020

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical ear

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical early warning of hydrologic drought. This paradigm faces an impending challenge given consensus that a smaller fraction of future precipitation will fall as snow. Here, we apply downscaled hydrologic simulations from 28 climate model projections to show that by mid-century (2036–2065), 69% of historically snowmelt-dominated areas of the western United States see a decline in the ability of snow to predict seasonal drought, increasing to 83% by late century (2070–2099). Reduced predictability arises when peak snowpack approaches zero or because of decreased warm-season runoff efficiency. Changes in drought prediction skill show significant (P < 0.01) elevation dependence, with lower-elevation coastal areas most impacted by warming. Ancillary predictive information can only partially mitigate snow-based predictability losses to 65% of areas, underscoring the importance of declining future snowpack.

Drought Management and Climate Adaptation of Small, Self-Sufficient Drinking Water Systems in California

California Energy Commission (CEC) | August 15th, 2018

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This study focuses on the 2012-2016 Drought in California, documenting how small self-sufficient drinking water systems were affected and challenged by, and responded to the extreme event.

Drought water right curtailment analysis for California’s Eel river

American Society of Civil Engineers (ASCE) | February 1st, 2018

Water users in California’s hybrid water rights system have different legal priorities to available surface water in times of water scarcity. A set of two linear progra

Water users in California’s hybrid water rights system have different legal priorities to available surface water in times of water scarcity. A set of two linear programming models was developed to determine curtailments of water use under drought conditions according to riparian and appropriative water right doctrines with spatially varying water availability and water rights within a basin. The models were implemented in spreadsheets and extended to estimate water right reliability and factors of safety in water rights administration. Alternate methods for calculating water use curtailments are discussed. Curtailments from the models are compared with actual water shortage notices issued by the state for the Eel River, California for June 30, 2014. Analyzing water use curtailments with an algorithm in spreadsheet software offers a mechanistic, transparent, accessible, and precise approach derived from legal doctrines to support water rights administration during drought.

Droughts in California

Public Policy Institute of California (PPIC) | April 1st, 2021