Colorado River

Future loss of Arctic sea-ice cover could drive a substantial decrease in California’s rainfall

Nature Portfolio (Springer Nature) | December 5th, 2017

From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter st

From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter storms were steered away from California by a persistent atmospheric ridging system in the North Pacific. Here we identify a new link between Arctic sea-ice loss and the North Pacific geopotential ridge development. In a two-step teleconnection, sea-ice changes lead to reorganization of tropical convection that in turn triggers an anticyclonic response over the North Pacific, resulting in significant drying over California. These findings suggest that the ability of climate models to accurately estimate future precipitation changes over California is also linked to the fidelity with which future sea-ice changes are simulated. We conclude that sea-ice loss of the magnitude expected in the next decades could substantially impact California’s precipitation, thus highlighting another mechanism by which human-caused climate change could exacerbate future California droughts.

Future precipitation increase from very high resolution ensemble downscaling of extreme atmospheric river storms in California

American Association for the Advancement of Science (AAAS) | July 15th, 2020

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often i

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often inadequately resolved by global climate models. In this analysis, we develop a framework involving targeted dynamical downscaling of historical and future extreme precipitation events produced by a large ensemble of a global climate model. This framework is applied to extreme “atmospheric river” storms in California. We find a substantial (10 to 40%) increase in total accumulated precipitation, with the largest relative increases in valleys and mountain lee-side areas. We also report even higher and more spatially uniform increases in hourly maximum precipitation intensity, which exceed Clausius- Clapeyron expectations. Up to 85% of this increase arises from thermodynamically driven increases in water vapor, with a smaller contribution by increased zonal wind strength. These findings imply substantial challenges for water and flood management in California, given future increases in intense atmospheric river-induced precipitation extremes.

Gage Gap

Nature Conservancy | October 31st, 2018

Following a difficult five-year drought, California just had one of the wettest winters on record. The state is famous for its highly engineered water system, whi

Following a difficult five-year drought, California just had one of the wettest winters on record. The state is famous for its highly engineered water system, which moves millions of gallons of water from north to south and east to west. Thirty-nine million people and our $47 billion agricultural industry rely on that water, not to mention wildlife from the Sierra to the sea. And yet we have surprisingly little data about how much water is moving through our streams at any given time. There are over 3,600 locations in California where stream gages have been active at some point, but only 54% have been active recently. And even fewer of those provide the kind of rich, real-time reporting needed to manage what is arguably our state’s most precious and contentious resource.

Geohydrology and ground-water-flow simulation of the Surprise Spring Basin aquifer system, San Bernardino, California

U.S. Geological Survey (USGS) | May 24th, 1991

Geohydrology of the Parker-Blythe-Cibola Area, Arizona and California

U.S. Geological Survey (USGS) | July 16th, 1973

The Parker-Blythe-Cibola area, as defined in this report, extends from the bedrock narrows north of Parker, Ariz., southward for about 85 miles along the valley of the Co

The Parker-Blythe-Cibola area, as defined in this report, extends from the bedrock narrows north of Parker, Ariz., southward for about 85 miles along the valley of the Colorado River to the bedrock narrows below Cibola, Ariz. The area is about midway between Hoover Dam and the Gulf of California. It includes parts of Yuma County, Ariz., and Imperial, Riverside, and San Bernardino Counties, Calif.

Geohydrology, Simulation of Regional Groundwater Flow, and Assessment of Water-Management Strategies, Twentynine Palms Area, California

U.S. Geological Survey (USGS) | June 28th, 2011

The Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, overlies the Surprise Spring, Deadman, Mesquite, and Mainside subbasins of the Morongo gr

The Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, overlies the Surprise Spring, Deadman, Mesquite, and Mainside subbasins of the Morongo groundwater basin in the southern Mojave Desert. Historically, the MCAGCC has relied on groundwater pumped from the Surprise Spring subbasin to provide all of its potable water supply. Groundwater pumpage in the Surprise Spring subbasin has caused groundwater levels in the subbasin to decline by as much as 190 feet (ft) from 1953 through 2007. Groundwater from the other subbasins contains relatively high concentrations of fluoride, arsenic, and (or) dissolved solids, making it unsuitable for potable uses without treatment. The potable groundwater supply in Surprise Spring subbasin is diminishing because of pumping-induced overdraft and because of more restrictive Federal drinking-water standards on arsenic concentrations. The U.S. Geological Survey, in cooperation with the MCAGCC, completed this study to better understand groundwater resources in the area and to help establish a long-term strategy for regional water-resource development. The Surprise Spring, Deadman, Mesquite, and Mainside subbasins are filled with sedimentary deposits of Tertiary age, alluvial fan deposits of Quaternary-Tertiary age, and younger alluvial and playa deposits of Quaternary age. Combined, this sedimentary sequence reaches a maximum thickness of more than 16,000 ft in the Deadman and Mesquite subbasins. The sedimentary deposits of Tertiary age yield a small amount of water to wells, and this water commonly contains high concentrations of fluoride, arsenic, and dissolved solids. The alluvial fan deposits form the principal water-bearing unit in the study area and have a combined thickness of 250 to more than 1,000 ft. The younger alluvial and playa deposits are unsaturated throughout most of the study area. Lithologic and downhole geophysical logs were used to divide the Quaternary/ Tertiary alluvial fan deposits into two aquifers (referred to as the upper and the middle aquifers) and the Tertiary sedimentary deposits into a single aquifer (referred to as the lower aquifer). In general, wells perforated in the upper aquifer yield more water than wells perforated in the middle and lower aquifers. The study area is dominated by extensive faulting and moderate to intense folding that has displaced or deformed the pre-Tertiary basement complex as well as the overlying Tertiary and Quaternary deposits. Many of these faults act as barriers to the lateral movement of groundwater flow and form many of the boundaries of the groundwater subbasins. The principal recharge to the study area is groundwater underflow across the western and southern boundaries that originates as runoff in the surrounding mountains. Groundwater discharges naturally from the study area as spring flow, as groundwater underflow to downstream basins, and as water vapor to the atmosphere by transpiration of phreatophytes and direct evaporation from moist soil. The annual volume of water that naturally recharged to or discharged from the groundwater flow system in the study area during predevelopment conditions was estimated to be 1,010 acre-feet per year (acre-ft/yr). About 90 percent of this recharge originated as runoff from the Little San Bernardino and the Pinto Mountains to the south, and the remainder originated as runoff from the San Bernardino Mountains to the west. Evapotranspiration by phreatophytes near Mesquite Lake (dry) was the primary form of predevelopment groundwater discharge. From 1953 through 2007, approximately 139,400 acre-feet (acre-ft) of groundwater was pumped by the MCAGCC from the Surprise Spring subbasin. A regional-scale numerical groundwater flow model was developed using MODFLOW–2000 for the Surprise Spring, Deadman, Mesquite, and Mainside subbasins. The aquifer system was simulated by using three model layers representing the upper, middle, and lower aquifers. Measured groundwater levels for predevelopment conditions (before 1953) and for the period 1953 through 2007 were used to calibrate the groundwater- flow model. The simulated steady-state (predevelopment) recharge was about 980 acre-ft/yr; about 90 percent of the recharge was in the Mesquite subbasin. Most of the simulated steady-state discharge occurred as evapotranspiration at the Mesquite Lake (dry). A total of about 145,450 acre-ft of groundwater was simulated as being pumped from the model domain during the transient simulation period (1953–2007); about 139,400 acre-ft of the total was extracted from the Surprise Spring subbasin. The transient simulation indicates that almost all of the groundwater pumped in the Surprise Spring subbasin comes from groundwater storage, which is consistent with the measured long-term declines in groundwater levels. The calibrated groundwater model was used to evaluate the potential effects on water levels and aquifer conditions in the Surprise Spring, Deadman, Mesquite, and Mainside subbasins for water-management strategies being considered by the MCAGCC to meet the projected water demand at the base for 2008–2017. One of the main objectives of the water-management strategies is to reduce pumpage from the Surprise Spring subbasin. Reducing groundwater pumpage in the Surprise Spring subbasin by about 38 percent (about 1,345 acre-ft/yr) substantially decreased or reversed simulated hydraulic-head declines in the subbasin. Redistributing about 15 percent of the 2007 groundwater pumpage (about 550 acre-ft/yr) from the Surprise Spring to the Mainside subbasin resulted in more than 60 ft of simulated declines in hydraulic head in the Mainside subbasin by 2017; however, redistributing about 22 percent of the 2007 pumpage (about 800 acre-ft/yr) from the Surprise Spring subbasin to the Deadman subbasin resulted in 5–10 ft of simulated hydraulic-head decline in the Deadman subbasin. The water-management scenarios simulated for this study demonstrate how the calibrated regional model can be utilized to evaluate the hydrologic effects of a water-management strategy.

Geology, Ground-Water Hydrology, Geochemistry, and Ground-Water Simulation of the Beaumont and Banning Storage Units, San Gorgonio Pass Area, Riverside County, California

U.S. Geological Survey (USGS) | December 14th, 2006

Ground-water has been the only source of potable water supply for residential, industrial, and agricultural users in the Beaumont and Banning storage units of the San Gor

Ground-water has been the only source of potable water supply for residential, industrial, and agricultural users in the Beaumont and Banning storage units of the San Gorgonio Pass area, Riverside County, California. Ground-water levels in the Beaumont area have declined as much as 100 feet between the early 1920s and early 2000s, and numerous natural springs have stopped flowing. In 1961, the San Gorgonio Pass Water Agency (SGPWA) entered into a contract with the California State Department of Water Resources to receive 17,300 acre-feet per year of water to be delivered by the California State Water Project (SWP) to supplement natural recharge. Currently (2005), a pipeline is delivering SWP water into the area, and the SGPWA is artificially recharging the ground-water system using recharge ponds located along Little San Gorgonio Creek in Cherry Valley with the SWP water. In addition to artificial recharge, SGPWA is considering the direct delivery of SWP water for the irrigation of local golf courses and for agricultural supply in lieu of ground-water pumpage. To better understand the potential hydrologic effects of different water-management alternatives on ground-water levels and movement in the Beaumont and Banning storage units, existing geohydrologic and geochemical data were compiled, new data from a basin-wide ground-water level and water-quality monitoring network were collected, monitoring wells were installed near the Little San Gorgonio Creek recharge ponds, geohydrologic and geochemical analyses were completed, and a ground-water flow simulation model was developed. The San Gorgonio Pass area was divided into several storage units on the basis of mapped or inferred faults. This study addresses primarily the Beaumont and Banning storage units. The geologic units in the study area were generalized into crystalline basement rocks and sedimentary deposits. The younger sedimentary deposits and the surficial deposits are the main water-bearing deposits in the San Gorgonio Pass area. The water-bearing deposits were divided into three aquifers: (1) the perched aquifer, (2) the upper aquifer, and (3) the lower aquifer based on lithologic and downhole geophysical logs. Natural recharge in the San Gorgonio Pass area was estimated using INFILv3, a deterministic distributed- parameter precipitation-runoff model. The INFILv3 model simulated that the potential recharge of precipitation and runoff in the Beaumont and Banning storage units was about 3,710 acre-feet per year and that the potential recharge in 28 sub-drainage basins upstream of the storage units was about 6,180 acre-feet per year. The water supply for the Beaumont and Banning storage units is supplied by pumping ground water from wells in the Canyon (Edgar and Banning Canyons), Banning Bench, Beaumont, and Banning storage units. Total annual pumpage from the Beaumont and Banning storage units ranged from about 1,630 acre-feet in 1936 to about 20,000 acre-feet in 2003. Ground-water levels declined by as much as 100 feet in the Beaumont storage unit from 1926–2003 in response to ground-water pumping of about 450,160 acre-feet during this period. Since ground-water development began in the San Gorgonio Pass area, there have been several sources of artificial recharge to the basin including return flow from applied water on crops, golf courses, and landscape; septic-tank seepage; and infiltration of storm runoff diversions and imported water into recharge ponds. Return flow from applied water and septic-tank seepage was estimated to reach a maximum of about 8,100 acre-feet per year in 2003. Owing to the great depth of water in much of study area (in excess of 150 feet), the return flow and septic-tank seepage takes years to decades to reach the water table. Stable-isotope data indicate that the source of ground-water recharge was precipitation from storms passing through the San Gorgonio Pass as opposed to runoff from the higher altitudes of the San Bernardino Mountains. In addition, these data indicate that little if any of the ground water in the fractured crystalline rocks flows across the Banning Fault into the Beaumont storage unit. Tritium concentrations indicate that little to no recharge has reached the water table since 1952 in most areas of the Beaumont and Banning storage units. In general, the uncorrected carbon-14 ages of ground water sampled from wells in the Beaumont, Banning, and surrounding storage units ranged from about 400 to 17,500 years before present. The older water was sampled in southeastern part of Beaumont storage unit and in the Banning storage unit, and ranged from 1,900 to 17,500 years before present. To better understand the dynamics of ground-water flow and the potential effects of water-level changes resulting from artificial recharge in the San Gorgonio Pass area, a regional-scale, numerical ground-water flow model was developed using MODFLOW-96. This model will be used by water managers to help manage the ground-water resources in the San Gorgonio Pass area. Results of the steady-state simulation indicate that the total inflow rate, or recharge, was about 6,590 acre-feet per year with about 3,710 acre-feet per year from areal recharge, about 2,670 acre-feet per year from mountain-front recharge, and about 210 acre-feet per year from the surrounding older sedimentary deposits. The simulated water budget for 1926–2003 indicates that of the total simulated volume of water pumped from the aquifer (450,160 acre-feet), about 50 percent was derived from depletion of ground-water storage (222,660 acre-feet), about 21 percent was derived from the reduction of underflow to the Cabazon and San Timoteo storage units (about 96,280 acre-feet), about 19 percent was derived from a reduction of ground-water outflow to the stream channels draining the San Timoteo storage unit (about 86,030 acre-feet), about 8 percent was derived from irrigation return flows and septic-tank seepage (about 36,780 acre-feet), and about 2 percent was derived from an increase in ground-water underflow from the surrounding older sedimentary deposits (about 8,410 acre-feet). The calibrated ground-water flow model was used to simulate the effects of four water-management scenarios being considered by SGPWA for the period 2004–13. In general, the results of the water-management scenarios indicate that artificial recharge in the Little San Gorgonio Creek recharge ponds primarily benefits the area north of the Cherry Valley Fault. For the scenario that used SWP water in lieu of ground water for golf course irrigation and for agricultural use, hydraulic heads increased by about 50 feet. None of the water-management scenarios significantly benefited the Banning storage unit.

Global climate mode resonance due to rapidly intensifying El Niño-Southern Oscillation

Publisher not available | October 16th, 2025

Increasing ENSO amplitude and teleconnection patterns imply that remote extratropical precipitation responses, such as in Southern California and the Iberian Peninsula (F

Increasing ENSO amplitude and teleconnection patterns imply that remote extratropical precipitation responses, such as in Southern California and the Iberian Peninsula (Fig. 5), will also become stronger between alternating El Niño and La Niña events. Even though the recurrence of these events may become more predictable due to the increased regularity/periodicity and amplitude (Fig. 1)44, future ENSO teleconnections might generate enhanced whiplash effects on hydroclimate, which requires additional planning and management strategies to minimize the costs of climate damage. While similar increases in ENSO regularity and amplitude can be found in some CMIP6 model projections (Fig. 2), future work needs to assess the detailed dynamics across these models and assess the likelihood of the ENSO regime changes seen in AWI-CM3.

Governing Nature: Bambi Law in a Wall-E World

Social Science Research Network (SSRN) | January 28th, 2021

Humanity has disrupted many of the fundamental processes that shape nature worldwide. Virtually no places remain unchanged. Many ecosystems have moved far from their hist

Humanity has disrupted many of the fundamental processes that shape nature worldwide. Virtually no places remain unchanged. Many ecosystems have moved far from their historic conditions and no longer support native species or traditional human uses. In the Anthropocene, a new geologic era dominated by the human impact on Earth, these problems will continue to get worse. In response, humans are intervening in ecosystems at a massive scale. This Article argues that, even as humanity engages in an unprecedented level of ecosystem management, existing environmental governance structures are ill suited to manage this new nature. Ecologists who focus on restoring ecosystems have begun to abandon efforts to recreate idealized historical ecosystems, recognizing that such efforts will fail. Instead, they embrace new approaches that acknowledge continuing human impacts and seek to shape impacted habitats in a way that benefits both human and other life. This Article examines the new ecological approaches, using their migration of purpose and approach to illuminate ecosystem management in the Anthropocene and the new obligations it places on environmental law. To sharpen this focus, the Article considers three case studies of managed ecosystems, detailing the extent to which humans are controlling nature. The case studies suggest that the existing literature seriously underestimates the magnitude of the questions society will soon face. The Article concludes that although we face the daunting prospect of reshaping the very fabric of nature, we lack the governance structures to decide what shape it should take. Society will need environmental law governance that can answer fundamental questions about humanity’s role in managing nature at all scales. This Article proposes several starting principles to encourage legal scholars to address this need.

Governor's Commission to Review California Water Rights Law Summary Final Report

State of California | December 1st, 1978