Colorado River

A western United States snow reanalysis dataset over the Landsat era from water years 1985 to 2021

Nature Portfolio (Springer Nature) | November 7th, 2022

Water stored in mountain snowpacks (i.e., snow water equivalent, SWE) represents an important but poorly characterized component of the terrestrial water cycle. The Weste

Water stored in mountain snowpacks (i.e., snow water equivalent, SWE) represents an important but poorly characterized component of the terrestrial water cycle. The Western United States snow reanalysis (WUS–SR) dataset is novel in its combination of spatial resolution (~500 m), spatial extent (31°–49° N; 102°–125° W), and temporal continuity (daily over 1985–2021). WUS–SR is generated using a Bayesian framework with model-based snow estimates updated through the assimilation of cloud-free Landsat fractional snow-covered area observations. Over the WUS, the peak SWE verification with independent in situ measurements show correlation coefficient, mean difference (MD), and root mean squared difference (RMSD) of 0.77, −0.15 m, and 0.28 m, respectively. The effects of forest cover and Landsat image availability on peak SWE are assessed. WUS–SR peak SWE is well correlated (ranging from 0.75 to 0.91) against independent lidar-derived SWE taken near April 1st, with MD

Achieving the Human Right to Water in California: An Assessment of the State's Community Water Systems

Office of Environmental Health Hazard Assessment (OEHHA) | January 15th, 2021

The Human Right to Water Framework and Data Tool (CalHRTW 1.0) provides a consolidated, stand-alone, quantitative assessment of baseline conditions in the quality, acces

The Human Right to Water Framework and Data Tool (CalHRTW 1.0) provides a consolidated, stand-alone, quantitative assessment of baseline conditions in the quality, accessibility and affordability of California’s drinking water. This assessment can help screen for drinking water challenges and analyze changes over time and complements existing cumulative impacts analyses (e.g., CalEnviroScreen (OEHHA, 2021b)) by providing information at a greater level of detail regarding drinking water.

Adaptability and adaptations of California’s water supply system to dry climate warming

Climactic Change (Springer) | November 27th, 2007

Economically optimal operational changes and adaptations for California’s water supply system are examined for a dry form of climate warming (GFDL CM2.1 A2) with year 2

Economically optimal operational changes and adaptations for California’s water supply system are examined for a dry form of climate warming (GFDL CM2.1 A2) with year 2050 water demands and land use. Economically adaptive water management for this climate scenario is compared to a similar scenario with the historical climate. The effects of population growth and land use alone are developed for comparison. Compared with the historic hydrology, optimized operations for the dry climate warming scenario raise water scarcity and total operation costs by $490 million/year with year 2050 demands. Actual costs might be somewhat higher where non-economic objectives prevail in water management. The paper examines the economical mix of adaptation, technologies, policies, and operational changes available to keep water supply impacts to such modest levels. Results from this screening model suggest promising alternatives and likely responses and impacts. Optimized operations of ground and surface water storage change significantly with climate. Dry-warm climate change increases the seasonal storage range of surface reservoirs and aquifers. Surface reservoir peak storage usually occurs about a month earlier under dry-warm climate change.

Addressing Stakeholder Science Needs for Integrated Drought Science in the Colorado River Basin

U.S. Geological Survey (USGS) | May 31st, 2022

Advances in Sub-seasonal to Seasonal Prediction Relevant to Water Management in the Western United States

American Meteorological Society (AMS) | July 21st, 2022

Water management in the semi-arid western United States (U.S.) is a challenging endeavor that evolves from year to year based on large-scale atmospheric and oceanic condi

Water management in the semi-arid western United States (U.S.) is a challenging endeavor that evolves from year to year based on large-scale atmospheric and oceanic conditions. This region has frequently experienced prolonged periods of drought with substantial socioeconomic impacts; the most recent instance involves California entering its third consecutive drought year. As context for the economic implications of drought, California’s enacted state budget for the Fiscal Year 2021-22 authorizes more than $600 million for the California Department of Water Resources for providing immediate drought support to local water agencies (CA State Budget 2021a); this amount is part of a package of more than $5 billion over four years for water resilience and drought preparedness (CA State Budget 2021b). For drought preparedness, state and local water managers would like to rely on skillful forecasts on timescales that span the spectrum between weather forecasts and climate predictions. Despite recent improvements in developing sub-seasonal (2- to 6-weeks lead) and seasonal (2- to 6-months lead) prediction systems that compete with and/or outperform existing dynamical and statistical models (e.g., Gibson et al. 2021, Switanek et al. 2020, DeFlorio et al. 2019), forecasting limitations have hindered crucial management decisions for western U.S. water managers, especially related to longer-lead planning, budgeting, resource allocation, and better preparedness for wet and dry extremes (DeFlorio et al. 2021). Improved understanding of physical phenomena and processes governing weather and climate extremes and utilization of emerging forecast methodologies are critical to developing skillful S2S forecast products relevant to water management.

Advancing Strategic Land Repurposing and Groundwater Sustainability in California

Environmental Defense Fund (EDF) | March 26th, 2021

For decades, California has been on a steady trajectory toward water scarcity, which is now exacerbated by climate change. More frequent and intense droughts and incre

For decades, California has been on a steady trajectory toward water scarcity, which is now exacerbated by climate change. More frequent and intense droughts and increased demands have affected the reliability of surface water supplies. As a result, many have looked to groundwater to fill the gap. Groundwater overpumping has resulted in adverse impacts such as reduction in groundwater storage, subsidence, water quality degradation, sea water intrusion, wells going dry and depletion of interconnected surface waters throughout many areas in California’s San Joaquin Valley. These impacts led to the passage of the Sustainable Groundwater Management Act (SGMA) by the state Legislature in 2014, which mandates sustainable use of groundwater by 2040 for the most critically overdrafted basins.

Agricultural risks from changing snowmelt

Nature Portfolio (Springer Nature) | April 20th, 2020

Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipita

Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipitation falling as snow and the timing of snowmelt, which may have profound effects on food production in basins where irrigated agriculture relies heavily on snowmelt runoff. Here, we analyse global patterns of snowmelt and agricultural water uses to identify regions and crops that are most dependent on snowmelt water resources. We find hotspots primarily in high-mountain Asia (the Tibetan Plateau), Central Asia, western Russia, western US and the southern Andes. Using projections of sub-annual runoff under warming scenarios, we identify the basins most at risk from changing snowmelt patterns, where up to 40% of irrigation demand must be met by new alternative water supplies under a 4 °C warming scenario. Our results highlight basins and crops where adaptation of water management and agricultural systems may be especially critical in a changing climate.

An Assessment of Urban Water Demand Forecasts in California

Pacific Institute | August 5th, 2020

In California, urban per capita water demand has declined dramatically over the past several decades, driven in part by greater uptake of water-efficient devices. These r

In California, urban per capita water demand has declined dramatically over the past several decades, driven in part by greater uptake of water-efficient devices. These reductions have important implications for estimating future water demand. However, failure to account for the long-term trend of declining per capita water demand has led to routine overestimation of future water demand. This can lead to unnecessary and costly investment in unneeded infrastructure and new sources of supply, higher costs, and adverse environmental impacts. This report examines the accuracy of long-range water demand forecasts for California’s 10 largest urban water suppliers. It finds that per capita water demand declined for all water suppliers between 2000 and 2015. In most cases, reductions in per capita water demand were so large that total water demand declined during this period. Additionally, all water suppliers overestimated demand, driven largely by inflated estimates of per capita water demand and, to a lesser extent, overestimates of population growth rates. The report offers recommendations on how to improve the accuracy of long-range water demand forecasts.

An Evolutionary Theory of Administrative Law

Southern Methodist University | May 25th, 2018

Law evolves to accommodate change—this is axiomatic in most academic legal traditions. But in the era of the administrative state, with congressional gridlock and a jud

Law evolves to accommodate change—this is axiomatic in most academic legal traditions. But in the era of the administrative state, with congressional gridlock and a judiciary hesitant to address policy questions, evolution of statutory law has become much more difficult. This leads to pent up demand for change in legal regimes. If the legislature and the courts cannot provide an outlet for this pressure, where does it go? How does the law continue to change? Although other scholars have looked to agencies as engines of legal change, we lack a theoretical framework to understand how that change happens. I argue that an evolutionary framework provides an informative framework for understanding administrative legal change. I provide three case studies that demonstrate the administrative evolution of the Endangered Species Act. In spite of tremendous advances in conservation, fundamental changes in scientists’ understanding of human impacts on the natural world, and increasingly strident clashes over private property rights and endangered species, the Act has remained largely unchanged for the last 35 years. In a functioning legislative system, the Act would have been amended to accommodate many of these changes. Instead, the case studies show a mechanism of legal change through agency action analogous to the mechanisms underlying biological evolution. Other commentators have argued the administrative state stymies evolution of the law, but this research contradicts that view. Applying an evolutionary framework to administrative actions creates a new theory of administrative evolution of the law, placing administrative analysis within the long tradition of evolutionary approaches to legal change used by commentators from Aristotle to Holmes. In contrast to traditional normative theories of administrative law, an evolutionary approach focuses on how change progresses over time. This theory of administrative evolution of the law also casts new light on a host of normative questions, from the role of judicial review to improvements in agency decision-making. Considering administrative actions within the broader context of the legal evolution promises a fruitful new approach to analyzing administrative law.

Analog Model Study of the Ground-Water Basin of the Upper Coachella Valley, California

U.S. Geological Survey (USGS) | July 18th, 1974

An analog model of the ground-water basin of the upper Coachella Valley was constructed to determine the effects of imported water on ground-water levels. The mod

An analog model of the ground-water basin of the upper Coachella Valley was constructed to determine the effects of imported water on ground-water levels. The model was considered verified when the ground-water levels generated by the model approximated the historical change in water levels of the ground-water basin caused by man's activities for the period 1936-67. The ground-water basin was almost unaffected by man's activities until about 1945 when ground-water development caused the water levels to begin to decline. The Palm Springs area has had the largest water-level decline, 75 feet since 1936, because of large pumpage, reduced natural inflow from the San Gorgonio Pass area, and diversions of natural inflows at Snow and Falls Creeks and Chino Canyon starting in 1945. The San Gorgonio Pass inflow had been reduced from about 13,000 acre-feet in 1936 to about 9,000 acre-feet by 1967 because of increased ground-water pumpage in the San Gorgonio Pass area, dewatering of the San Gorgonio Pass area that took place when the tunnel for the Metropolitan Water District of Southern California was drilled, and diversions ofsurface inflow at Snow and Falls Creeks. In addition, 1944-64 was a period of below-normal precipitation which, in part, contributed to the declines in water levels in the Coachella Valley. The Desert Hot Springs, Garnet Hill, and Mission Creek subbasins have had relatively little development; consequently, the water-level declines have been small, ranging from 5 to 15 feet since 1936. In the Point Happy area a decline of about 2 feet per year continued until 1949 when delivery of Colorado River water to the lower valley through the Coachella Canal was initiated. Since 1949 the water levels in the Point Happy area have been rising and by 1967 were above their 1936 levels. The Whitewater River subbasin includes the largest aquifer in the basin, having sustained ground-water pumpage of about 740,000 acre-feet from 1936 to 1967, and will probably continue to provide the most significant supply of ground water for the upper valley. The total ground-water storage depletion for the entire upper valley for 1936-67 was about 600,000 acre-feet, an average stor age decrease of about 25,000 acre-feet per year since 1945. Transmissivity for the Whitewater River subbasin ranges from 360,000 gal- lons per day per foot (near Point Happy) to 50,000 gallons per day per foot, with most of the subbasin about 300,000 gallons per day per foot. In contrast, the transmissivities of the Desert Hot Springs, Mission Creek, and Garnet Hill sub-basins generally range from 2,000 to 100,000, but the highest value, beneath the Mission Creek streambed deposits, is 200,000 gallons per day per foot; the transmissivity for most of the area of the three subbasins is 30,000 gallons per day per foot. The storage coefficients are representative of water-table conditions, ranging from 0.18 beneath the Mission Creek stream deposits to 0.06 in the Palm Springs area. The model indicated that the outflow at Point Happy decreased from 50,000 acre-feet in 1936 to 30,000 acre-feet by 1967 as a result of the rising water levels in the lower valley. The most logical area to recharge the Colorado River water is the Windy Point-Whitewater area, where adequate percolation rates of 2 4 acre-feet per acre per day are probable. The Whitewater River bed may be the best location to spread the water if the largest part of the imported water can be recharged during low-flow periods. The area in sec. 21, T. 2 S., R. 4 E., would be adequate for the smaller quantities of recharge proposed for the Mission Creek area. Projected pumpage for the period 1968-2000 was programed on the model with the proposed recharge of Colorado River water for the same period. The model indicated a maximum water-level increase of 200 feet above the 1967 water level at Windy Point, the proposed recharge site, by the year 2000, a 130-foot increase by 1990, and a 20-foot increase by 1980. The model indicated that the proposed quantities of recharge will beneficially affect the ground-water system to Palm Desert by 1980, to Point Happy by 1990, and possibly to the Coachella Canal by 2000. The model indicated that the upper and lower valleys are within the same hydrologic system, and it has been proposed that the model be extended to the Salton Sea. On the basis of the available analyses, changes in the quality of ground water in the Whitewater River subbasin after recharge apparently will be, as a first approximation, proportional to the ratio in which the quantity of recharge and the quantity of ground water are mixed. Where mixing does not occur, the quality of the recharge water will probably not be greatly changed by ion-exchange phenomenon.