South Lahontan

Analysis of Potential Water-Supply Management Options, 2010-60, and Documentation of Revisions to the Model of the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

U.S. Geological Survey (USGS) | October 31st, 2014

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional, finite-difference groundwater-flow model—the U.S. Geological Survey’s MOD-FLOW—of the aquifer system in the basin was updated and the initial input dataset was supplemented with groundwater withdrawal data for the period 2000–10. The updated model was then used to simulate four combinations, or scenarios, of groundwater withdrawal and recharge over the next 50 years (January 2011 through December 2060). The scenarios included combinations of continuing withdrawals from currently active production wells, supplementing any increases in demand with withdrawals from an inactive production well, reducing withdrawal amounts and rates, and reducing the discharge of treated wastewater to infiltration ponds that provide a recharge source to the underlying aquifer. Results of the simulations indicated that, depending on the scenario implemented, groundwater levels would rise (over the next 50 years) from 40 feet to as much as 65 feet in the northwestern part of the Irwin Basin, and from 5 feet to 10 feet in the southeastern part.

Annual Ground-Water Discharge by Evapotranspiration from Areas of Spring-Fed Riparian Vegetation Along the Eastern Margin of Death Valley, 2000–02

U.S. Geological Survey (USGS) | July 1st, 2006

Annual Owens Valley Operations Plan for the 2023-24 Runoff Year

Los Angeles Department of Water & Power (LADWP) | April 25th, 2023

Annual Owens Valley Operations Plan for the 2024-25 Runoff Year

Los Angeles Department of Water & Power (LADWP) | June 20th, 2024

Antelope Valley Groundwater Cases

Superior Court of California, County of Los Angeles | December 23rd, 2015

The complaints and cross-complaints in the Action frame many legal issues. The Action includes over 4,000 Parties, as well as the members of the Non-Pumper Class and the

The complaints and cross-complaints in the Action frame many legal issues. The Action includes over 4,000 Parties, as well as the members of the Non-Pumper Class and the members of the Small Pumper Class. The Basin’s entire Groundwater supply and Groundwater rights, extending over approximately 1390 square miles, have been brought to issue. The numerous Groundwater rights at issue in the case include, without limitation, overlying, appropriative, prescriptive, and federal reserved water rights to Groundwater, rights to return flows from Imported Water, rights to recycled water, rights to stored Imported Water subject to the Watermaster rules and regulations, and rights to utilize the storage space within the Basin. After several months of trial, the Court made findings regarding Basin characteristics and determined the Basin’s Safe Yield. The Court’s rulings and judgments in this case, including the Safe Yield determination, form the basis for this Judgment. For annual reports go to the Department of Water Resources Adjudicated Annual Reporting page.

Anthropogenic warming drives earlier wildfire season onset in California

American Association for the Advancement of Science (AAAS) | August 8th, 2025

Annual wildfire area in California has rapidly grown in recent decades, with increasingly negative impacts on people. The fire season is also lengthening, with an earlier

Annual wildfire area in California has rapidly grown in recent decades, with increasingly negative impacts on people. The fire season is also lengthening, with an earlier onset. This trend has been hypothesized to be driven by anthropogenic warming, but it has yet to be quantitatively attributed to climate drivers. Using a comprehensive fire occurrencedataset, we analyze fire season onset and climate controls on its variability and change during 1992–2020 in 13 California ecoregions. Northern California ecoregions show stronger trends toward earlier onset compared to more arid southern California ecoregions. Onset has trended earlier for all but one ecoregion. Interannual variability of onset is dominated by climate variability and its influence on fuel moisture. Trend attribution inferred from onset-climate relationships suggests that anthropogenic warming advanced fire season onset by 6 to 46 days during 1992–2020 in 11of 13 ecoregions. Continued warming is expected to further promote earlier fire season onsets.

Anthropogenic warming impacts on California snowpack during drought

American Geophysical Union (AGU) | March 15th, 2017

Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of t

Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of the twentieth century anthropogenic warming. Anthropogenic warming reduced average snowpack levels by 25%, with middle‐to‐low elevations experiencing reductions between 26 and 43%. In terms of event frequency, return periods associated with anomalies in 4 year 1 April snow water equivalent are estimated to have doubled, and possibly quadrupled, due to past warming. We also estimate effects of future anthropogenic warmth on snowpack during a drought similar to that of 2011–2015. Further snowpack declines of 60–85% are expected, depending on emissions scenario. The return periods associated with future snowpack levels are estimated to range from millennia to much longer. Therefore, past human emissions of greenhouse gases are already negatively impacting statewide water resources during drought, and much more severe impacts are likely to be inevitable.

Anthropogenic Warming Impacts on Today's Sierra Nevada Snowpack and Flood Risk

American Geophysical Union (AGU) | June 15th, 2018

This study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which followed

This study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which followed the extraordinary California drought of 2011–2015. By perturbing near‐surface temperatures from a 9‐km dynamically downscaled simulation, a series of offline land surface model experiments explore how Sierra Nevada hydrology has already been impacted by historical anthropogenic warming and how these impacts evolve under future warming scenarios. Results show that historical warming reduced 2016–2017 Sierra Nevada snow water equivalent by 20% while increasing early‐season runoff by 30%. An additional one third to two thirds loss of snowpack is projected by the end of the century, depending on the emission scenario, with middle elevations experiencing the most significant declines. Notably, the number of days in the future with runoff exceeding 20 mm nearly doubles under a mitigation emission scenarios and triples under a business‐as‐usual scenario. A smaller snow‐to‐rain ratio, as opposed to increased snowmelt, is found to be the primary mechanism of temperature impacts to Sierra snowpack and runoff. These findings are consequential to the prevalence of early‐season floods in the Sierra Nevada. In the Feather River Watershed, historical warming increased runoff by over one third during the period of heaviest precipitation in February 2017. This suggests that historical anthropogenic warming may have exacerbated runoff conditions underlying the Oroville Dam spillway overflow that occurred in this month. As warming continues in the future, the potential for runoff‐based flood risk may rise even higher.

Anticipating responses to climate change and planning for resilience in California’s freshwater ecosystems

National Academy of Sciences (NAS) | July 29th, 2024

Application of Satellite Data to Model Storm Runoff Into Rosamond Dry Lake

Loyola Marymount University | October 15th, 2014

Antelope Valley is situated in Southern California and is bounded by the Tehachapi and the San Gabriel Mountains. It stretches over 2,200 mi2 and encompasses Rosamond Dry

Antelope Valley is situated in Southern California and is bounded by the Tehachapi and the San Gabriel Mountains. It stretches over 2,200 mi2 and encompasses Rosamond Dry Lake and the 1,200 mi2 watershed draining into it. The cities of Lancaster and Palmdale are the two major urban centers that lie in the watershed draining into Rosamond Dry Lake. The lake lies within the vicinity of the Edwards Air Force Base and provides an important site for aviation research and test operations in addition to ecosystem services. Hence, it is necessary to balance the need to remove water from the lake to support Edwards Air Force Base’s aircraft missions and the need to inundate the lake to protect the its surface and the ecosystem it supports.