South Coast

Mapping Structural Control Through Analysis of Land-Surface Deformation for the Rialto-Colton Groundwater Subbasin, San Bernardino County, California, 1992–2010

U.S. Geological Survey (USGS) | July 29th, 2022

The locations of many faults in and near the Rialto-Colton groundwater subbasin are not precisely known because the spatial density of existing lithologic and hydrologic

The locations of many faults in and near the Rialto-Colton groundwater subbasin are not precisely known because the spatial density of existing lithologic and hydrologic data used to infer the locations of faults can be sparse. The U.S. Geological Survey, in cooperation with the San Bernardino Valley Municipal Water District, analyzed structural control of groundwater flow in and near the Rialto-Colton groundwater subbasin using Interferometric Synthetic Aperture Radar (InSAR) methods. Faults commonly are barriers to groundwater flow, and the high spatial resolution of InSAR imagery can be used to infer the locations of buried faults where groundwater pumping occurs. InSAR results have revealed three areas in and near the Rialto-Colton groundwater subbasin where buried faults are interpreted as groundwater-flow barriers: the northwestern area about 3 miles northwest of the City of Rialto, the San Jacinto fault area west of the City of San Bernardino, and the southeastern area about 2 miles southeast of the City of Colton. The InSAR results were combined with knowledge gained from previous studies to better define the location and extent of faults acting as groundwater-flow barriers. New data about faults acting as groundwater-flow barriers can be incorporated into future conceptual and hydrologic models of the Rialto-Colton groundwater subbasin and provide water managers information to help effectively manage groundwater resources.

Maps, Models, and Mystery: Interconnected Groundwater and the Public Trust

American Bar Association (ABA) | August 10th, 2019

Walk into the office of any water law practitioner, anywhere, and you might think you made a wrong turn and walked into the office of your local cartographer. We are a p

Walk into the office of any water law practitioner, anywhere, and you might think you made a wrong turn and walked into the office of your local cartographer. We are a profession that depends on, and you might even say reveres, a good map. Rights to water flowing in surface streams are fundamentally defined by geography, and maps have long been a requirement of appropriation and essential evidence of riparian ownership. In turn, injury to a surface water right is determined by physics, as the topography of the land establishes the linear relation of impacts from other diversions, whether it be upstream (cause), or downstream (affected). In homage to these principles, some hydrologists will orient their maps top-to-bottom as upstream to downstream, rather than north to south. In our practice, gravity is our compass. Upending the convenient simplicity of rivers and streams flowing from mountaintop to ocean are alluvial and glacial valleys, in which unconsolidated sediment serve as giant sponges and blocks of fractured rock contain hidden stores of oftentimes ancient waters. Through these geologic features, hidden beneath the surface, water percolates, flows, and moves across the landscape. These subsurface waterbodies interconnect with surface streams and changes in the groundwater basin, whether due to drought or artificial extractions, and influence surface flow on a time scale ranging from minutes to centuries. To understand the relationship with any hope of precision, we need much more than a map; we need a hydrogeologist and a whole lot of data. All of this is by way of introducing two themes of emerging law in California that stand to influence trends beyond the state: (1) the legal relevance of interconnected groundwater to surface flows in protecting instream uses, and (2) recognition in the law of the need to understand and manage these interconnected waters.

Marine heatwaves in the Northeast Pacific intensify landfalling atmospheric rivers on the west coast of North America

Nature Portfolio (Springer Nature) | July 23rd, 2026

Extreme precipitation along the west coast of North America is often associated with atmospheric rivers (ARs), fueled by evaporation from the ocean. When ARs interact wit

Extreme precipitation along the west coast of North America is often associated with atmospheric rivers (ARs), fueled by evaporation from the ocean. When ARs interact with marine heatwaves (MHWs), they can form compound extreme events with amplified hydrological impacts. Here, we quantify how MHWs influence the intensity and precipitation of landfalling ARs through thermodynamic air–sea interaction processes. We use high-resolution regional coupled ocean–atmosphere ensemble simulations to isolate the influence of large-scale MHW-related sea surface temperature (SST) anomalies while constraining the synoptic-scale atmospheric circulation. Focusing on well-documented AR events during the 2013–16 Northeast Pacific MHW, we show that anomalously warm SSTs enhance evaporation and lower-tropospheric moisture availability, leading to a robust increase in integrated vapor transport and intensified landfalling ARs. The enhanced moisture transport results in earlier onset and substantially increased coastal precipitation, particularly over drought-vulnerable regions of California. Moisture-budget diagnostics demonstrate that this amplification arises from a direct thermodynamic response to SST anomalies, rather than indirect modulation through changes in large-scale atmospheric circulation. Insights gained from this case study identify a thermodynamic pathway linking MHWs and ARs, highlighting the role of persistent oceanic thermal anomalies in shaping compound hydrological extremes under continued climate warming.

Maximizing ENSO as a source of western US hydroclimate predictability

Climate Dynamics (Springer) | October 16th, 2019

Until recently, the El Niño–Southern Oscillation (ENSO) was considered a reliable source of winter precipitation predictability in the western US, with a historically

Until recently, the El Niño–Southern Oscillation (ENSO) was considered a reliable source of winter precipitation predictability in the western US, with a historically strong link between extreme El Niño events and extremely wet seasons. However, the 2015–2016 El Niño challenged our understanding of the ENSO-precipitation relationship. California precipitation was near-average during the 2015–2016 El Niño, which was characterized by warm sea surface temperature (SST) anomalies of similar magnitude compared to the extreme 1997–1998 and 1982–1983 El Niño events. We demonstrate that this precipitation response can be explained by El Niño’s spatial pattern, rather than internal atmospheric variability. In addition, observations and large-ensembles of regional and global climate model simulations indicate that extremes in seasonal and daily precipitation during strong El Niño events are better explained using the ENSO Longitude Index (ELI), which captures the diversity of ENSO’s spatial patterns in a single metric, compared to the traditional Niño3.4 index, which measures SST anomalies in a fixed region and therefore fails to capture ENSO diversity. The physically-based ELI better explains western US precipitation variability because it tracks the zonal shifts in tropical Pacific deep convection that drive teleconnections through the response in the extratropical wave-train, integrated vapor transport, and atmospheric rivers. This research provides evidence that ELI improves the value of ENSO as a predictor of California’s seasonal hydroclimate extremes compared to traditional ENSO indices, especially during strong El Niño events.

Measuring Progress Toward Universal Access to Water and Sanitation in California: Defining Goals, Indicators, and Performance Measures

Pacific Institute | September 15th, 2018

In January 2018, over half a million Californians were served by water utilities that were out of compliance with the Safe Drinking Water Act (SDWA). The worst outbreak o

In January 2018, over half a million Californians were served by water utilities that were out of compliance with the Safe Drinking Water Act (SDWA). The worst outbreak of Hepatitis A in recent memory occurred in 2016-2018 due to open defecation and lack of handwashing facilities for persons experiencing homelessness. California’s tribes continue to face problems of poor housing and water and sanitation service, with two-thirds of tribal communities reporting inadequate home plumbing in 2015.1 And the cost of water has increased for many, particularly among small and medium size systems, with 39 community water systems in the state charging more than $100 a month for 12 CCF of water. In response to the problem, California enacted the Human Right to Water in 2012, declaring that “Every human being has the right to safe, clean, affordable, and accessible water adequate for human consumption, cooking, and sanitary purposes.”

Memorandum Report on the Floods of January and February 1969 in the Southern District of the Department of Water Resources

California Department of Water Resources (DWR) | February 27th, 1970

Memorialization and Memory of Southern California's St. Francis Dam Disaster of 1928

California State University, Northridge (CSUN) | August 1st, 2014

The commemoration of disasters is a product of social, cultural, economic, and  political forces in human society. Southern California's largely unheard-of St. Francis D

The commemoration of disasters is a product of social, cultural, economic, and  political forces in human society. Southern California's largely unheard-of St. Francis Dam Disaster of 1928 provides an excellent opportunity to study this complex process of commemoration, engaging memory within difference frames of reference. In particular, evaluating how and why this man-made dam disaster has been forgotten on a state and national level, but tenuously remembered within the flood-zone, allows for consideration of the diversity of commemorative processes in the construction of memory and heritage related to major catastrophes.

Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms: Biological responses to ocean acidification

Ecology Letters (Wiley) | August 16th, 2010

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acid

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non-calcifying organisms across numerous response variables, with the exception ofcrustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate.Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.

Methane emissions from groundwater pumping in the USA

Nature Portfolio (Springer Nature) | March 25th, 2019

Atmospheric methane accumulation contributes to climate change, hence quantifying methane emissions is essential to assess and model the impacts. Here, we estimate metha

Atmospheric methane accumulation contributes to climate change, hence quantifying methane emissions is essential to assess and model the impacts. Here, we estimate methane emissions from groundwater pumping in the Los Angeles Basin (LAB), north-eastern Pennsylvania, and the Principal aquifers of the USA using the average concentrations of methane in groundwater and annual groundwater pumping volumes. High average methane concentrations, 44.1 mg/L, and extensive groundwater pumping, ~3.1 Å~1011 L/a in the LAB, result in the annual emission of ~2.9 Å~ 10−3 Tg of microbial methane. Ethane emissions in the LAB were 3.5 Å~10−6 Tg/a. Lower methane emissions estimated for NE Pennsylvania, ~3.0 Å~ 10−8 Tg/a, reflect lower methane concentrations and groundwater pumping, 0.7 mg/L and 4.67 Å~ 107 L/a, respectively. Methane concentrations and groundwater withdrawals, 1.06 Å~1014 L/a, across the USA enabled the estimation of the total emissions of methane from Principal aquifers (92% of total pumping) of 0.044 Tg/a in the year 2000, which represents a small percentage (~0.2%) of the total annual US methane emissions, but a previously unquantified flux in the global methane budget. Globally, groundwater-pumping methane emissions were estimated to be 0.53 Tg/a, 0.2% of global methane emissions, by adopting a global estimate for groundwater extraction, and an average methane concentration in older groundwater of 0.44 mg/L.

Microplastic pollution in the water column and benthic sediment of the San Pedro Bay, California, USA

Environmental Research (Elsevier) | January 21st, 2025

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of m

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of microplastics at the sea surface. To address this gap, we conducted one of the first comprehensive assessments of microplastic distribution through the marine water column and benthic sediment during the wet and dry season in the coastal waters of the San Pedro Bay Southern California, USA. Microplastic concentrations in the water column did not vary significantly across season but were significantly higher in nearshore environments and at the surface of the water column. Sediment samples contained significantly more microplastics in the wet season and in offshore environments. Black particles were the most dominant color, while fibers were the most abundant morphology, accounting for over 50% of both water column and sediment microplastics. Polyethylene and polypropylene were identified as the most abundant polymers in the water column regardless of morphology type. Tire and road wear particles were found through the study domain. Average microplastic concentrations in the San Pedro Bay were estimated to be 8.65 × 105 ± 7.60 × 105 particles/km2 and 3.19 ± 2.96 particles/m³. This study highlights the complexity of microplastic concentration, character, and distribution in marine environments and demonstrates that surface only sampling strategies significantly underestimate microplastic concentrations. Our findings underscore the need for continued and expanded research into microplastic distribution and transport dynamics across the marine environment to aid in understanding, managing, and mitigating plastic pollution in coastal marine systems.