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.

Identifying wastewater chemicals in coastal aerosols

American Association for the Advancement of Science (AAAS) | May 28th, 2025

The Tijuana River, at the US-Mexico border, discharges millions of gallons of wastewater daily—sewage, industrial waste, and runoff—into the Pacific Ocean, making it

The Tijuana River, at the US-Mexico border, discharges millions of gallons of wastewater daily—sewage, industrial waste, and runoff—into the Pacific Ocean, making it the dominant source of coastal pollution in this region. This study examines how such wastewater influences coastal aerosols by tracking spatial gradients from near the border northward. Using benzoylecgonine (a nonvolatile cocaine metabolite) as a sewage tracer, we find that wastewater compounds—including a mixture of illicit drugs, drug metabolites, and chemicals from tires and personal care products—become aerosolized and are detectable in both water and air. Spatial analyses confirm that most measured chemicals concentrate in aerosols near the Tijuana River, potentially exposing local populations to tens of nanograms per hour (e.g., octinoxate and methamphetamine) via inhalation. This airborne pathway highlights a largely overlooked source of atmospheric pollution, emphasizing the need to reassess health risks in coastal regions as global water contamination continues to escalate.

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.

Impact of extreme drought and incentive programs on flooded agriculture and wetlands in California’s Central Valley

PeerJ | June 29th, 2018

Between 2013 and 2015, a large part of the western United States, including the Central Valley of California, sustained an extreme drought. The Central Valley is recogniz

Between 2013 and 2015, a large part of the western United States, including the Central Valley of California, sustained an extreme drought. The Central Valley is recognized as a region of hemispheric importance for waterbirds, which use flooded agriculture and wetlands as habitat. Thus, the impact of drought on the distribution of surface water needed to be assessed to understand the effects on waterbird habitat availability.Methods: We used remote sensing data to quantify the impact of the recent extreme drought on the timing and extent of waterbird habitat during the non-breeding season (July–May) by examining open water in agriculture (rice, corn, and other crops) and managed wetlands across the Central Valley. We assessed the influence of habitat incentive programs, particularly The Nature Conservancy’s BirdReturns and The Natural Resources Conservation Service’s Waterbird Habitat Enhancement Program (WHEP), at offsetting habitat loss related to drought.Results: Overall, we found statistically significant declines in open water in post-harvest agriculture (45–80% declines) and in managed wetlands (39–60% declines) during the 2013–2015 drought compared to non-drought years during the period of 2000–2011. Crops associated with the San Joaquin Basin, specifically corn, as well as wetlands in that part of the Central Valley exhibited larger reductions in open water than rice and wetlands in the Sacramento Valley. Semi-permanent wetlands on protected lands had significantly lower (39–49%) open water in the drought years than those on non-protected lands while seasonal wetlands on protected lands had higher amounts of open water. A large fraction of the daily open water in rice during certain times of the year, particularly in the fall for BirdReturns (61%) and the winter for WHEP (100%), may have been provided through incentive programs which underscores the contribution of these programs. However, further assessment is needed to know how much the incentive programs directly offset the impact of drought in post-harvest rice by influencing water management or simply supplemented funding for activities that might have been done regardless. Discussion: Our landscape analysis documents the significant impacts of the recent extreme drought on freshwater wetland habitats in the Central Valley, the benefits of incentive programs, and the value of using satellite data to track surface water and waterbird habitats. More research is needed to understand subsequent impacts on the freshwater dependent species that rely on these systems and how incentive programs can most strategically support vulnerable species during future extreme drought.

Impact of underground storm drain systems on larval ecology of Culex and Aedes species in urban environments of Southern California

Nature Portfolio (Springer Nature) | July 16th, 2021

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant product

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant production habitats for mosquitoes. Knowledge of whether USDS habitats are suitable for newly introduced dengue vectors Aedes aegypti and Ae. albopictus will help guide surveillance and control efforts. To determine whether the USDS functions as a suitable larval habitat for Culex, Ae. aegypti and Ae. albopictus in southern California, we examined mosquito habitat utilization and larval survivorship using laboratory microcosm studies. The data showed that USDS constituted 4.1% of sampled larval habitats for Ae. aegypti and Ae. albopictus, and 22.0% for Cx. quinquefasciatus. Furthermore, USDS water collected in the summer completely inhibited Aedes larval development, but yielded a 15.0% pupation rate for Cx. quinquefasciatus. Food supplementation in the microcosms suggests that nutrient deficiency, toxins and other factors in the USDS water led to low success or complete failure of larval development. These results suggest that USDS habitats are currently not major productive larval habitats for Aedes mosquitoes in southern California. Our findings prompt inclusion of assessments of pupal productivity in USDS habitats and adult mosquito resting sites in the mosquito surveillance program.

Impacts of California’s Five-Year (2012-2016) Drought on Hydroelectricity Generation

Pacific Institute | April 13th, 2017

The severe hydrological drought afflicting California between 2012 and 2016 has ended, with an extremely wet winter beginning in October 2016. That five-year per

The severe hydrological drought afflicting California between 2012 and 2016 has ended, with an extremely wet winter beginning in October 2016. That five-year period was the driest and hottest in the instrumental record going back to the late 1800s. Impacts on communities, ecosystems, farmers, and the economy were widespread but have been unevenly distributed. The Pacific Institute has regularly analyzed the consequences of California droughts, beginning with comprehensive assessments of the 1987-1992 drought (Gleick and Nash 1991, Nash 1993), the 2007-2009 drought (Christian-Smith et al. 2011), and this most recent drought (Cooley et al. 2015, Gleick 2015, Cooley et al. 2016, Feinstein et al. 2017). This analysis is the third assessment of the impacts of the drought on hydropower production and greenhouse gas emissions from California’s energy sector (Gleick 2015, Gleick 2016). This analysis finds that during the five years ending September 30, 2016 (the end of the 2016 “water year”), hydropower generation was substantially below average, and the associated economic cost to California ratepayers was approximately $2.45 billion dollars. The additional combustion of fossil fuels for electricity generation also led to a 10 percent increase in carbon dioxide emissions from California’s in-state power plants (CARB 2015) along with increased emissions of other pollutants.

Impacts of California’s Ongoing Drought: Agriculture

Pacific Institute | August 26th, 2015

California’s agriculture sector has exceeded expectations during the most severe drought in recorded history at the cost of massive but unsustainable groundwater pumpin

California’s agriculture sector has exceeded expectations during the most severe drought in recorded history at the cost of massive but unsustainable groundwater pumping. Continued groundwater overdraft, while reducing the economic impacts of the drought for the agricultural sector now, has shifted the burden to others, including current and future generations forced to dig deeper wells, find alternative drinking water sources, and repair infrastructure damaged by subsidence. That is the conclusion of the new study, Impacts of California’s Ongoing Drought: Agriculture, released today by the Pacific Institute, an independent global water think tank. This new study is the first comprehensive analysis of the actual impacts of the drought on California agricultural revenue and employment through 2014 – the last year for which data are available. The study, drawing on data from the USDA National Agricultural Statistics Survey and the California Employment Development Department, analyzes acreage, revenue, and employment figures from 2000-2014. Production costs, impacts on animal or nursery products, or regional impacts are not examined because these data are not yet available. The study’s results provide critical insight into how the state can maintain a healthy agriculture sector in a future likely to see less water, more extreme weather, and greater uncertainty. California remains the largest agricultural producer in the U.S. in total output and in exports. During the drought, California’s agriculture sector has experienced record-high crop revenue and employment. Last year farmers harvested 640,000 fewer acres, which was 9 percent below pre-drought levels, yet crop revenue remained strong. Indeed, crop revenue peaked in 2013 at $34 billion – the highest level in California history. In 2014, crop revenue declined by $480 million, representing a 1.4 percent reduction from 2013 levels. All economic estimates have been corrected for inflation. Statewide agriculture-related jobs also reached a record-high of 417,000 people in 2014, highlighting the sector’s ability to withstand the reduction of available water.

Impacts of California’s Ongoing Drought: Hydroelectricity Generation

Pacific Institute | March 17th, 2015

California’s hottest and driest drought in recorded history is shifting the sources of energy for electricity with adverse economic and environmental consequences. The

California’s hottest and driest drought in recorded history is shifting the sources of energy for electricity with adverse economic and environmental consequences. The Pacific Institute, an internationally-renowned independent think tank focused on water issues, released a report that reveals diminished river flows have resulted in less hydroelectricity, more expensive electricity, and increased production of greenhouse gas emissions. “This severe drought has many negative consequences. One of them that receives little attention is how the drought has fundamentally changed the way our electricity is produced,” said the report’s author, Pacific Institute President Peter Gleick. “We hope this report prompts a lively debate on how to factor in a changing climate when we plan for electricity generation,” he added. Under normal conditions, electricity for the state’s millions of users is produced from a blend of many sources, with natural gas and hydropower being the top two. Since the drought has reduced the state’s river flows that power hundreds of hydropower stations, natural gas has become a more prominent player in the mix. This is an expensive change. According to the Institute’s report, between October 2011 and October 2014, California’s ratepayers spent $1.4 billion more for electricity than in average years because of the drought-induced shift from hydropower to natural gas. In an average year, hydropower provides 18 percent of the electricity needed for agriculture, industry, and our homes. Comparatively, in this three-year drought period, hydropower comprised less than 12 percent of total California electricity generation. A longer view reveals an even more startling economic impact: factoring in the dry years from 2007-2009, the total additional energy cost to the state’s electricity users during the six years of recent drought was $2.4 billion. This further reliance on natural gas for the state’s electricity production also has environmental costs. Hydropower produces few or no air contaminants, whereas burning natural gas emits many pollutants, including climate-changing greenhouse gases. During the 2011- 2014 drought period, burning more natural gas to compensate for limited hydropower led to an eight-percent increase in emissions of carbon dioxide and other pollutants from California power plants. If the current drought persists, water flowing to drive hydroelectric turbines will continue to shrink and expensive and polluting natural gas will become even more of a factor in the electricity production game.

Impacts of California’s Ongoing Drought: Hydroelectricity Generation 2015 Update

Pacific Institute | February 1st, 2016

The Pacific Institute has released a comprehensive assessment of the costs to California of lost hydroelectricity during the four years of drought from October 2011 to th

The Pacific Institute has released a comprehensive assessment of the costs to California of lost hydroelectricity during the four years of drought from October 2011 to the end of September 2015 (the official California “water year” runs from October 1 to September 30). Under normal conditions, electricity for the state’s millions of users is produced from a blend of many sources, with natural gas and hydropower being the top two. Since the drought has reduced the state’s river flows that power hundreds of hydropower stations, natural gas has become a more prominent player in the mix. This is an expensive change. According to the Institute’s new report, the four years of drought led to an increase in electricity costs of more than $2.0 billion. The additional combustion of fossil fuels for electric generation also led to a 10 percent increase in the release of carbon dioxide from California power plants. “The impacts of the California drought – which is the driest and the hottest in 120 years of instrumental records and one of the worst in history – has had widespread  impacts on all water users, including farmers, industries, cities, and natural ecosystems,” said the report’s author, Pacific Institute President Peter Gleick. “And in fact, all California ratepayers are affected by the drought as they pay for electricity that is both dirtier and more expensive than in non-drought years.” In addition, the report notes that the ability to expand California’s hydroelectric capacity is limited, as there are few undammed rivers, little unallocated water, and growing environmental, economic, and political constraints to adding new hydropower capacity.