Identification of Bacteria in Groundwater Used for Domestic Supply in the Southeast San Joaquin Valley, California, 2014

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

Groundwater is an important source of drinking water in California. Water-borne diseases caused by microbial contamination are a growing concern. The MI test, a membrane

Groundwater is an important source of drinking water in California. Water-borne diseases caused by microbial contamination are a growing concern. The MI test, a membrane filtration method for the chromogenic / fluorogenic detection of total coliforms and Escherichia coli, was used for samples collected January to April 2014 from 42 domestic wells in the southeastern San Joaquin Valley. The wells were sampled as part of the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP), a cooperative study between the U.S. Geological Survey and the California State Water Resources Control Board. Polymerase chain reaction analysis and sequencing of deoxyribonucleic acid (DNA) were used for 34 target and nontarget colonies that grew on the MI media from samples collected from 13 of the domestic wells to identify what genera of bacteria could exist in groundwater used by domestic wells. Gene sequences obtained using the Sanger method were entered into the basic local alignment search tool (BLAST) database, and 17 genera of bacteria were identified. Of these, 13 genera contain species that are human pathogens or opportunistic human pathogens. All the genera that include human pathogens are naturally present in soil, plants, or water; one of the pathogens also can be found in fecal matter. Six of the human pathogens were from non-target colony growth on the MI media. Target and non-target microbial growth on MI media are indicators of the possible presence of pathogenic bacteria even if the bacteria naturally are from soil rather than from a fecal source.

Identifying and Addressing Contaminant Sources Impacting an Urban Estuary

San Francisco Estuary Institute (SFEI) | July 1st, 2016

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 Anthropogenic CO2 on the CaCO3 System in the Oceans

American Association for the Advancement of Science (AAAS) | July 16th, 2004

Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to greater CO2 uptake by the oceans. This acidification process has changed

Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to greater CO2 uptake by the oceans. This acidification process has changed the saturation state of the oceans with respect to calcium carbonate (CaCO3) particles. Here we estimate the in situ CaCO3 dissolution rates for the global oceans from total alkalinity and chlorofluorocarbon data, and we also discuss the future impacts of anthropogenic CO2 on CaCO3 shell–forming species. CaCO3 dissolution rates, ranging from 0.003 to 1.2 micromoles per kilogram per year, are observed beginning near the aragonite saturation horizon. The total water column CaCO3 dissolution rate for the global oceans is approximately 0.5  0.2 petagrams of CaCO 3-C per year, which is approximately 45 to 65% of the export production of CaCO 3.

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.

Impacts of Surface Water Diversions for Marijuana Cultivation on Aquatic Habitat in Four Northwestern California Watersheds

PLOS | March 18th, 2015

Marijuana (Cannabis sativa L.) cultivation has proliferated in northwestern California since at least the mid-1990s. The environmental impacts associated with marijuana c

Marijuana (Cannabis sativa L.) cultivation has proliferated in northwestern California since at least the mid-1990s. The environmental impacts associated with marijuana cultivation appear substantial, yet have been difficult to quantify, in part because cultivation is clandestine and often occurs on private property. To evaluate the impacts of water diversions at a watershed scale, we interpreted high-resolution aerial imagery to estimate the number of marijuana plants being cultivated in four watersheds in northwestern California, USA. Low-altitude aircraft flights and search warrants executed with law enforcement at cultivation sites in the region helped to validate assumptions used in aerial imagery interpretation. We estimated the water demand of marijuana irrigation and the potential effects water diversions could have on stream flow in the study watersheds. Our results indicate that water demand for marijuana cultivation has the potential to divert substantial portions of streamflow in the study watersheds, with an estimated flow reduction of up to 23% of the annual seven-day low flow in the least impacted of the study watersheds. Estimates from the other study watersheds indicate that water demand for marijuana cultivation exceeds streamflow during the low-flow period. In the most impacted study watersheds, diminished streamflow is likely to have lethal or sub-lethal effects on state-and federally-listed salmon and steelhead trout and to cause further decline of sensitive amphibian species.

Impacts of the 2014 severe drought on the Microcystis bloom in San Francisco Estuary

Harmful Algae (Elsevier) | February 17th, 2017

The increased frequency and intensity of drought with climate change may cause an increase in the magnitude and toxicity of freshwater cyanobacteria harmful algal blooms

The increased frequency and intensity of drought with climate change may cause an increase in the magnitude and toxicity of freshwater cyanobacteria harmful algal blooms (CHABs), including Microcystis blooms, in San Francisco Estuary, California. As the fourth driest year on record in San Francisco Estuary, the 2014 drought provided an opportunity to directly test the impact of severe drought on cyanobacteria blooms in SFE. A field sampling program was conducted between July and December 2014 to sample a suite of physical, chemical, and biological variables at 10 stations in the freshwater and brackish reaches of the estuary. The 2014 Microcystis bloom had the highest biomass and toxin concentration, earliest initiation, and the longest duration, since the blooms began in 1999. Median chlorophyll a concentration increased by 9 and 12 times over previous dry and wet years, respectively. Total microcystin concentration also exceeded that in previous dry and wet years by a factor of 11 and 65, respectively. Cell abundance determined by quantitative PCR indicated the bloom contained multiple potentially toxic cyanobacteria species, toxic Microcystis and relatively high total cyanobacteria abundance. The bloom was associated with extreme nutrient concentrations, including a 20-year high in soluble reactive phosphorus concentration and low to below detection levels of ammonium. Stable isotope analysis suggested the bloom varied with both inorganic and organic nutrient concentration, and used ammonium as the primary nitrogen source. Water temperature was a primary controlling factor for the bloom and was positively correlated with the increase in both total and toxic Microcystis abundance. In addition, the early initiation and persistence of warm water temperature coincided with the increased intensity and duration of the Microcystis bloom from the usual 3 to 4 months to 8 months. Long residence time was also a primary factor controlling the magnitude and persistence of the bloom, and was created by a 66% to 85% reduction in both the water inflow and diversion of water for agriculture during the summer. We concluded that severe drought conditions can lead to a significant increase in the abundance of Microcystis and other cyanobacteria, as well as their associated toxins.

Implementing Ecosystem Based Management

Duke Environmental Law & Policy Forum | June 7th, 2021

Implicit and Explicit Biases for Recycled Water and Tap Water

American Geophysical Union (AGU) | May 31st, 2022

Increasing use of recycled water to irrigate agricultural products and decreasing consumption of bottled water are important components of sustainable water management pr

Increasing use of recycled water to irrigate agricultural products and decreasing consumption of bottled water are important components of sustainable water management practices and consumer-driven efforts to improve water security and quality. However, consumers frequently discount agricultural products irrigated with recycled water relative to products irrigated with conventional water and place a premium on bottled water relative to tap water. This study measures consumer attitudes regarding recycled water and bottled water to understand more fully the reasons behind these preferences. We conduct two studies involving 2,616 adult consumers in the United States designed to measure consumer attitudes and preferences: the use of recycled water versus conventional water to irrigate food products and tap water versus bottled water for drinking. In each study, implicit attitudes are measured using an Implicit Association Test as well as explicit attitudes. We find that respondents have negative implicit attitudes regarding recycled water compared to conventional water and tap water compared to bottled water, and a negative explicit attitude toward recycled water. Tap water and food grown with recycled water were believed to be less healthy to consume and less tasty, although these are believed to be more sustainable options. Beliefs about water attributes (i.e., healthfulness, taste, and sustainability) are associated with attitudes, and both beliefs about attributes and attitudes are associated with preferences for products. Further, we find that respondents' stated preferences are consistent with their implicit and explicit attitudes.

Inadequate Government-Led Water-Quality Monitoring Hinders Improvement Efforts in the Salton Sea

University of California, Los Angeles (UCLA) | September 4th, 2025

California’s largest inland body of water, the Salton Sea, has faced severe environmental degradation, leaving lasting impacts on surrounding desert communities. Situat

California’s largest inland body of water, the Salton Sea, has faced severe environmental degradation, leaving lasting impacts on surrounding desert communities. Situated between Riverside and Imperial counties, the lake has endured the effects of jurisdictional challenges, climate change, and unsustainable agricultural practices that have exacerbated nutrient pollution to levels surpassing those found in most lakes across the United States. Data collected over 16 years of quarterly government sampling and 12 months of high-frequency sampling—conducted collaboratively by local communities and the University of California, Los Angeles—consistently reveal high concentrations of nitrates and dangerously low oxygen levels in the water column. These nutrient-rich conditions create an environment conducive to hydrogen sulfide emissions, which persist around the Salton Sea at levels that exceed health standards and raise ongoing concerns within the community. The State of California and the federal government are contractually obligated to restore the Salton Sea. To address the water-quality issues and their consequences, we recommend a combination of environmental and economic remediation efforts aimed at improving the Salton Sea’s ecosystem and its resulting impact on nearby communities.