Central Coast

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.

Detection and Measurement of Land-Surface Deformation, Pajaro Valley, Santa Cruz and Monterey Counties, California, 2015–18

U.S. Geological Survey (USGS) | October 22nd, 2021

Land-surface deformation (subsidence) caused by groundwater withdrawal is identified as an undesirable result in the Pajaro Valley Water Management Agency’s Basin Manag

Land-surface deformation (subsidence) caused by groundwater withdrawal is identified as an undesirable result in the Pajaro Valley Water Management Agency’s Basin Management Plan and California’s Sustainable Groundwater Management Act. In Pajaro Valley, groundwater provides nearly 90 percent of the total water supply. To aid the development of sustainable groundwater management criteria, the U.S. Geological Survey, in cooperation with the Pajaro Valley Water Management Agency, performed an analysis of land-surface deformation (subsidence and uplift) in Pajaro Valley for 2015–18, using Interferometric Synthetic Aperture Radar and continuous Global Positioning System methods. Land-surface deformation results were then compared with subsurface geology and groundwater altitudes to better understand the hydromechanical response of the coastal aquifer system. The results indicate the land surface is generally stable with only small magnitudes (less than 1 inch) of seasonal land-surface deformation (subsidence in the summer and uplift in the winter) during 2015–18. During this time, the largest magnitude of land-surface deformation was less than 2 inches of subsidence and was localized in one area just north of the city limits of Watsonville, California. Groundwater altitudes during 2015–18 demonstrated seasonal variability and annual to multi-annual increases after reaching historical lows by the mid-1990s. The small magnitudes of land-surface deformation coupled with groundwater-altitude increases in most areas indicate that the subsidence likely is largely elastic and recoverable. The Corralitos-Pajaro Valley groundwater basin contains fine-grained (clay) sediments that have the potential for permanent aquifer-system compaction and resultant land subsidence. However, groundwater altitudes throughout the Pajaro Valley have increased above historical lows, and observed increases in groundwater altitudes coincided with changes in groundwater management activities. Observed relations between groundwater management activities and groundwater altitudes indicate that management of groundwater supplies could minimize the potential for permanent land-surface deformation in Pajaro Valley.

Detections of current-use pesticides at 12 surface water sites in California during a 2-year period beginning in 2015

U.S. Geological Survey (USGS) | July 27th, 2018

Surface water samples were collected by the U.S. Geological Survey and multiple cooperators during base flow/irrigation runoff and storm runoff conditions from 12 sites t

Surface water samples were collected by the U.S. Geological Survey and multiple cooperators during base flow/irrigation runoff and storm runoff conditions from 12 sites throughout California, over 2 consecutive years beginning in April 2015, from both urban and agriculturally dominated watersheds. Water samples were analyzed by gas chromatography/mass spectrometry and liquid chromatrography/tandem mass spectrometry for a suite of 157 pesticides and degradates. Suspended sediments associated with these water samples were analyzed by gas chromatography/mass spectrometry for a suite of 131 pesticides and degradates. Overall, 85 pesticides and degradates were detected in the water: 32 fungicides, 25 herbicides, 27 insecticides, and 1 synergist. In the suspended sediment, 29 pesticides were detected: 9 fungicides, 10 herbicides, and 10 insecticides. Sixteen pesticides (bifenthrin, carbendazim, chlorpyrifos, clothianidin, diazinon, diuron, fenpyroximate, fipronil, fipronil sulfone, fluopicolide, imidacloprid, metolachlor, novaluron, oxyflurofen, permethrin, and simazine) were detected in the water at concentrations that were above at least one aquatic life benchmark value as defined by the U.S Environmental Protection Agency.

Developing Adaptation Strategies for San Luis Obispo: Preliminary Climate Change Vulnerability Assessment for Social Systems

California Energy Commission (CEC) | July 31st, 2012

San Luis Obispo faces a variety of risks from climate change, including extreme heat, a generally drier climate, increases in extreme weather events, and sea-level rise.

San Luis Obispo faces a variety of risks from climate change, including extreme heat, a generally drier climate, increases in extreme weather events, and sea-level rise. Important vulnerabilities are apparent for water supplies, in agriculture (especially for wine and cattle ranchers) and related tourism, for fishing, coastal tourism, coastal development and infrastructure, and for community services. Certain county populations may face disproportionate risks including the elderly, those already affected by diseases, and outdoor and migrant workers from extreme heat, people living in coastal and inland floodplains, those living at the wildland-urban interface, the student population, institutionalized individuals (especially the state hospital), and those members of the community that tend to be somewhat disenfranchised from public decision-making, such as non-English speaking individuals and those who can’t afford to take off from work to attend public meetings. The county is wise to begin planning and building its adaptive capacity at this time before climate change impacts become more severe, and before there may be greater competition for state and federal financial support for adaptation planning and implementation.

Developing agricultural pest management strategies with reduced-risks to surface water: An economic case study of California's Central Coast region

Elsevier | May 4th, 2024

Development and Calibration of a Two-Dimensional Digital Model for the Analysis of the Ground-Water Flow System in the San Antonio Creek Valley, Santa Barbara County, California

U.S. Geological Survey (USGS) | August 1st, 1985

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.

Documentation of Model Input and Output Values for the Geohydrology and Mathematical Simulation of the Pajaro Valley Aquifer System, Santa Cruz and Monterey Counties, California

U.S. Geological Survey (USGS) | July 14th, 1990

As part of a study of the geology and hydrology of the Pajaro Valley aquifer system, Santa Cruz and Monterey Counties, California, a three-layer mathematical mode

As part of a study of the geology and hydrology of the Pajaro Valley aquifer system, Santa Cruz and Monterey Counties, California, a three-layer mathematical model was developed, using the computational algorithm of McDonald and Harbaugh (1984). The results of the Pajaro Valley study are given by Johnson and others (1988).

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.