Colorado River

Hydroclimate Report Water Year 2018

California Department of Water Resources (DWR) | March 31st, 2020

Water year (WY) 2018 whipsawed from dry to wet and added high heat for the summer. The WY ended with 82 percent of average precipitation in the Northern Sierra and 20 per

Water year (WY) 2018 whipsawed from dry to wet and added high heat for the summer. The WY ended with 82 percent of average precipitation in the Northern Sierra and 20 percent below average April-July streamflow in the Sacramento River and 19 percent below average for the San Joaquin River. Peak statewide snowpack was only 60 percent of average. While precipitation and stream flow were below average, the big story of the 2018 WY were record temperatures that lead to several unprecedented and deadly wildfires in the state.

Hydroclimate Report Water Year 2019

California Department of Water Resources (DWR) | June 30th, 2020

Water year (WY) 2019 continued to demonstrate effects of climate change with greater variability and more extremes. Hydroclimate extremes presented themselves with atmosp

Water year (WY) 2019 continued to demonstrate effects of climate change with greater variability and more extremes. Hydroclimate extremes presented themselves with atmospheric rivers causing both flooding and heavy snowpack. Before the wet winter and spring months, California experienced a very dry fall in where the devastating Camp Fire started on November 8, 2018 in Butte County. Fall transitioned to into a wet winter with 64 percent of the WY total for the DWR Northern 8-station index falling in the three months of January, February and March. Temperatures went from extreme cold in February to hot in August as the year progressed from winter to summer.

Hydroclimate Report Water Year 2020

California Department of Water Resources (DWR) | August 31st, 2021

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were ne

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were new extremes with a very dry February and very hot end to the water year. Late fall precipitation onset continued with the first significant storm of the year arriving in late November. The WY ended with 67 percent of average precipitation statewide and 62 percent of average in the Northern Sierra. For runoff, the Sacramento Basin had 66 percent of average April-July streamflow while the San Joaquin Basin had 58 percent of average. Peak statewide snowpack was 62 percent of average reaching that point in early April with a late season storm providing some offset to the winter’s dryness. February was one of the big stories of WY 2020 with record low precipitation. In a year of extremes, August and September also contributed record warmth for the month including a 130-degree Fahrenheit reading at Death Valley on August 16, 2020. This observation, if verified by the World Meteorological Organization, would be one of the hottest daily temperature maximums recorded on Earth. Several cities set new records for days above 90 degrees as well.

Hydroclimate Report Water Year 2021

California Department of Water Resources (DWR) | December 31st, 2022

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there were new extremes with a record dry and warm spring being most notable. Late fall onset occurred again this year arriving in late November starting the seasonal snowpack on very dry soils. The WY ended with 48 percent of average precipitation statewide making it the second driest year in 126 years of record. It was also second warmest for statewide average temperature. For two-year totals, WY 2021 set a record, recording less precipitation than WY 1977. There was only one significant storm in the WY in late January which included low elevation snow and very strong damaging winds. The April 1 statewide snowpack registered 62% of average. Peak snowpack at 64% of average occurred the week before April 1. Runoff from the snowpack was far below expectations due to the dry antecedent conditions and record dry and warm spring. The lack of runoff resulted in the need for emergency drought response measures.

Hydroclimate Report Water Year 2022

California Department of Water Resources (DWR) | October 1st, 2024

Hydroclimate response of spring ecosystems to a two‐stage Younger Dryas event in western North America

Nature Portfolio (Springer Nature) | May 5th, 2022

The Younger Dryas (YD) climate event is the preeminent example of abrupt climate change in the recent geologic past. Climate conditions during the YD were spatially compl

The Younger Dryas (YD) climate event is the preeminent example of abrupt climate change in the recent geologic past. Climate conditions during the YD were spatially complex, and high-resolution sediment cores in the North Atlantic, western Europe, and East Asia have revealed it unfolded in two distinct stages, including an initial stable climatic period between ~ 12.9 and 12.2 ka associated with a weakened Atlantic Meridional Overturning Circulation (AMOC) and a second phase characterized by variable conditions until 11.7 ka as the AMOC recovered. Decades of investigations into the climate of western North America during the YD have failed to identify this stepped phenomenon. Here we present hydroclimate data from paleospring deposits in Death Valley National Park (California, USA) that demonstrate unequivocal evidence of two-stage partitioning within the YD event. High groundwater levels supported persistent and long-lived spring ecosystems between ~ 13.0 and 12.2 ka, which were immediately replaced by alternating wet and dry environments until ~ 11.8 ka. These results establish the mid-YD climate transition extended into western North America at approximately the same time it was recorded by hydrologic systems elsewhere in the Northern Hemisphere and show that even short-lived changes in the AMOC can have profound consequences for ecosystems worldwide.

Hydroclimate volatility on a warming Earth

Nature Portfolio (Springer Nature) | January 9th, 2025

Hydrogeology and Simulation of Groundwater Flow in the Lucerne Valley Groundwater Basin, California

U.S. Geological Survey (USGS) | June 28th, 2022

The Lucerne Valley is in the southwestern part of the Mojave Desert and is about 75 miles northeast of Los Angeles, California. The Lucerne Valley groundwater basin encom

The Lucerne Valley is in the southwestern part of the Mojave Desert and is about 75 miles northeast of Los Angeles, California. The Lucerne Valley groundwater basin encompasses about 230 square miles and is separated from the Upper Mojave Valley groundwater basin by splays of the Helendale Fault. Since its settlement, groundwater has been the primary source of water for agricultural, industrial, municipal, and domestic uses. Groundwater withdrawal from pumping has exceeded the amount of water recharged to the basin, causing groundwater declines of more than 100 feet between 1917 and 2016 in the center of the basin. The continued withdrawal has resulted in an increase in pumping costs, reduced well efficiency, and land subsidence near Lucerne Lake. Although the volume of pumping has declined in recent years, there is concern that new agricultural growth and limits on imported water will continue to strain the sustainability of the groundwater system.

Hydrogeology, Hydrologic Effects of Development, and Simulation of Groundwater Flow in the Borrego Valley, San Diego County, California

U.S. Geological Survey (USGS) | November 24th, 2015

The Borrego Valley is a small valley (110 square miles) in the northeastern part of San Diego County, California. Although the valley is about 60 miles northeast of city

The Borrego Valley is a small valley (110 square miles) in the northeastern part of San Diego County, California. Although the valley is about 60 miles northeast of city of San Diego, it is separated from the Pacific Ocean coast by the mountains to the west and is mostly within the boundaries of Anza-Borrego Desert State Park. From the time the basin was first settled, groundwater has been the only source of water to the valley. Groundwater is used for agricultural, recreational, and municipal purposes. Over time, groundwater withdrawal through pumping has exceeded the amount of water that has been replenished, causing groundwater-level declines of more than 100 feet in some parts of the basin. Continued pumping has resulted in an increase in pumping lifts, reduced well efficiency, dry wells, changes in water quality, and loss of natural groundwater discharge. As a result, the U.S. Geological Survey began a cooperative study of the Borrego Valley with the Borrego Water District (BWD) in 2009. The purpose of the study was to develop a greater understanding of the hydrogeology of the Borrego Valley Groundwater Basin (BVGB) and to provide tools to help evaluate the potential hydrologic effects of future development. The objectives of the study were to (1) improve the understanding of groundwater conditions and land subsidence, (2) incorporate this improved understanding into a model that would assist in the management of the groundwater resources in the Borrego Valley, and (3) use this model to test several management scenarios. This model provides the capability for the BWD and regional stakeholders to quantify the relative benefits of various options for increasing groundwater storage. The study focuses on the period 1945–2010, with scenarios 50 years into the future.

Hydrologic Components for Model Development, Chapter C of Death Valley Regional Ground-Water Flow System, Nevada and California—Hydrogeologic Framework and Transient Ground-Water Flow Model

U.S. Geological Survey (USGS) | July 1st, 2004