Effects of wildfire on benthic macroinvertebrate assemblages in Southern California streams and implications for bioassessment monitoring programs

California State Water Resources Control Board (SWRCB) | June 13th, 2012

Wildfires are common in arid regions of southern California, sometimes burning as much as half a million acres in a season. These fires often cause dramatic impacts to th

Wildfires are common in arid regions of southern California, sometimes burning as much as half a million acres in a season. These fires often cause dramatic impacts to the vegetation and soils of regional watersheds and, consequently, to the streams that drain them. Water quality programs that monitor and regulate these systems have to account for the influence of these factors upon water quality measurements when making monitoring and regulatory decisions. This is true for traditional water quality measures (nutrients, metals, contaminants, etc.), but is especially important for integrative ecological condition indicators like bioassessment, the use of resident biological communities to infer water quality condition.

Efficient Water Use in California: Water Rights, Water Districts, and Water Transfers

Rand Corporation (Rand) | November 13th, 1978

El Niño-like teleconnection increases California precipitation in response to warming

Nature Portfolio (Springer Nature) | July 7th, 2017

Future California (CA) precipitation projections, including those from the most recent Climate Model Intercomparison Project (CMIP5), remain uncertain. This uncertainty i

Future California (CA) precipitation projections, including those from the most recent Climate Model Intercomparison Project (CMIP5), remain uncertain. This uncertainty is related to several factors, including relatively large internal climate variability, model shortcomings, and because CA lies within a transition zone, where mid-latitude regions are expected to become wetter and subtropical regions drier. Here, we use a multitude of models to show CA may receive more precipitation in the future under a business-as-usual scenario. The boreal winter season-when most of the CA precipitation increase occurs-is associated with robust changes in the mean circulation reminiscent of an El Niño teleconnection. Using idealized simulations with two different models, we further show that warming of tropical Pacific sea surface temperatures accounts for these changes. Models that better simulate the observed El Niño-CA precipitation teleconnection yield larger, and more consistent increases in CA precipitation through the twenty-first century.

Electrical Resistivity Imaging of Seawater Intrusion into the Monterey Bay Aquifer System

National Groundwater Association (NGWA) | June 17th, 2015

We use electrical resistivity tomography to obtain a 6.8‐km electrical resistivity image to a depth of approximately 150 m.b.s.l. along the coast of Monterey Bay. The

We use electrical resistivity tomography to obtain a 6.8‐km electrical resistivity image to a depth of approximately 150 m.b.s.l. along the coast of Monterey Bay. The resulting image is used to determine the subsurface distribution of saltwater‐ and freshwater‐saturated sediments and the geologic controls on fluid distributions in the region. Data acquisition took place over two field seasons in 2011 and 2012. To maximize our ability to image both vertical and horizontal variations in the subsurface, a combination of dipole–dipole, Wenner, Wenner‐gamma, and gradient measurements were made, resulting in a large final dataset of approximately 139,000 data points. The resulting resistivity section extends to a depth of 150 m.b.s.l., and is used, in conjunction with the gamma logs from four coastal monitoring wells to identify four dominant lithologic units. From these data, we are able to infer the existence of a contiguous clay layer in the southern portion of our transect, which prevents downward migration of the saltwater observed in the upper 25 m of the subsurface to the underlying freshwater aquifer. The saltwater and brackish water in the northern portion of the transect introduce the potential for seawater intrusion into the hydraulically connected freshwater aquifer to the south, not just from the ocean, but also laterally from north to south.

Electrical Resistivity Investigation of Fluvial Geomorphology to Evaluate Potential Seepage Conduits to Agricultural Lands along the San Joaquin River, Merced County, California, 2012–13

U.S. Geological Survey (USGS) | ?

Increased flows in the San Joaquin River, part of the San Joaquin River Restoration Program, are designed to help restore fish populations. However, increased seepage los

Increased flows in the San Joaquin River, part of the San Joaquin River Restoration Program, are designed to help restore fish populations. However, increased seepage losses could result from these higher restoration flows, which could exacerbate existing drainage problems in neighboring agricultural lands and potentially damage crops. Channel deposits of abandoned river meanders that are hydraulically connected to the river could act as seepage conduits, allowing rapid and widespread water-table rise during restoration flows. There is a need to identify the geometry and properties of these channel deposits to assess their role in potential increased seepage effects and to evaluate management alternatives for reducing seepage. Electrical and electromagnetic surface geophysical methods have provided a reliable proxy for lithology in studies of fluvial and hyporheic systems where a sufficient electrical contrast exists between deposits of differing grain size. In this study, direct-current (DC) resistivity was used to measure subsurface resistivity to identify channel deposits and to map their subsurface geometry. The efficacy of this method was assessed by using DC resistivity surveys collected along a short reach of the San Joaquin River in Merced County, California, during the summers of 2012 and 2013, in conjunction with borings and associated measurements from a hydraulic profiling tool. Modeled DC resistivity data corresponded with data from analyses of core samples, hand-auger samples, a hydraulic profiling tool, and aerial photographs, confirming that DC resistivity was effective for differentiating between silty and sandy deposits in this setting. Modeled DC resistivity data provided detailed two-dimensional cross-sectional resistivity profiles to a depth of about 20 meters. The distribution of high-resistivity units in these profiles was used as a proxy for identifying areas of high hydraulic conductivity. Estimates of the cross-sectional area of channel deposits from DC resistivity pseudosections can provide critical input for groundwater-flow models designed to simulate river seepage and evaluate seepage-management alternatives.

Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp

American Association for the Advancement of Science (AAAS) | July 17th, 2024

Elevated Grand Canyon groundwater recharge during the warm Early Holocene

Nature Portfolio (Springer Nature) | October 2nd, 2023

Summer rainfall is an important contributor to water budgets in western North American deserts, where intense rainfall sustains ecosystems while also causing flash floods

Summer rainfall is an important contributor to water budgets in western North American deserts, where intense rainfall sustains ecosystems while also causing flash floods and damaging erosion. A better understanding of Grand Canyon palaeoclimate and the long-term history of the summer monsoon from summer-sensitive palaeoclimate records will improve our ability to project future hydroclimatic changes under warmer conditions. Here we show multi-proxy evidence for an intensification of the Early Holocene (11,700–8,200 years ago) hydrological cycle linked to a stronger and expanded summer North American Monsoon from calcite oxygen and uranium isotopes in a uranium-series precisely dated stalagmite from a Grand Canyon cave. Our results suggest that subsurface infiltration was greater in the Early Holocene than today at Grand Canyon. A data–model comparison with an isotope-enabled climate model suggests that enhanced infiltration was due to an Early Holocene monsoon intensification associated with rising atmospheric temperature. Projections of a future increase in precipitation intensity or more frequent and expanded North American monsoon rain events may paradoxically result in increased subsurface infiltration at Grand Canyon and other high-altitude plateaus, even within the context of western North American aridification in a hotter climate.

Elevation and Opportunity in the Delta: Restoring the Right Thing in the Right Place

San Francisco Estuary Institute (SFEI) | May 31st, 2022

A future Sacramento-San Joaquin Delta and Suisun Marsh (“Delta” herein) that supports healthy ecosystems and native species, while also meeting flood risk reduction,

A future Sacramento-San Joaquin Delta and Suisun Marsh (“Delta” herein) that supports healthy ecosystems and native species, while also meeting flood risk reduction, water supply, water quality, carbon sequestration, economic, and cultural objectives, requires that appropriate restoration and management actions be taken in the right place at the right time. Geographic setting affects the potential opportunities available—not all actions are suitable everywhere. Physical factors determining what types of activities are appropriate now and in the future include a site’s elevation, degree of tidal and fluvial influence, salinity, soil type, and local effects of climate change, which all vary spatially across the Delta. While there has been considerable progress over the last several decades, continued acceleration of the pace and scale of enhancement actions appropriate to landscape position is needed. Understanding the physical template is necessary for developing strategies that move beyond opportunistic restoration, support resilience over time, and have the potential to connect and magnify benefits across the larger landscape.

Elsinore Valley Subbasin Groundwater Sustainability Plan

Elsinore Valley Municipal Water District | December 23rd, 2021

The Elsinore Valley Subbasin is located within the service area of Elsinore Valley Municipal Water District (EVMWD or District). No other agencies overlap the boundaries

The Elsinore Valley Subbasin is located within the service area of Elsinore Valley Municipal Water District (EVMWD or District). No other agencies overlap the boundaries of this subbasin therefore no inter-agency coordination was required for the development of this GSP. Two outside technical experts participated as the technical advisory committee for the GSP development. EVMWD conducted public outreach throughout the development of the GSP.

Emergency Drought Barriers

Delta Stewardship Council (Delta Council) | April 26th, 2022