Sacramento and San Joaquin river basins: Procedures for hydrologic analysis

U.S. Army Corps of Engineers (USACE) | September 9th, 2008

The primary purpose of this document is to describe the methods and procedures we will use to complete the hydrologic analysis of the Sacramento and San Joaquin river b

The primary purpose of this document is to describe the methods and procedures we will use to complete the hydrologic analysis of the Sacramento and San Joaquin river basins. Specifically, we describe the required inputs, models, analysis, and anticipated results. This description will give the HAC an opportunity to review, in advance, the procedures for the hydrologic analysis. The secondary purpose of this paper is to initiate development of a project management plan (PMP) by outlining specific procedural tasks to be completed in the hydrologic analysis.

Science and Decision Making: Water Management and Tree‐Ring Data in the Western United States

American Water Resources Association (AWRA) | October 5th, 2009

Growing populations, limited resources, and sustained drought are placing increased pressure on already over‐allocated water supplies in the western United States, prom

Growing populations, limited resources, and sustained drought are placing increased pressure on already over‐allocated water supplies in the western United States, prompting some water managers to seek out and utilize new forms of climate data in their planning efforts. One source of information that is now being considered by water resource management is extended hydrologic records from tree‐ring data. Scientists with the Western Water Assessment (WWA) have been providing reconstructions of streamflow (i.e., paleoclimate data) to water managers in Colorado and other western states (Arizona, New Mexico, and Wyoming), and presenting technical workshops explaining the applications of tree‐ring data for water management for the past eight years. Little is known, however, about what has resulted from these engagements between scientists and water managers. Using in‐depth interviews and a survey questionnaire, we attempt to address this lack of information by examining the outcomes of the interactions between WWA scientists and western water managers to better understand how paleoclimate data has been translated to water resource management. This assessment includes an analysis of what prompts water managers to seek out tree‐ring data, how paleoclimate data are utilized by water managers in both quantitative and qualitative ways, and how tree‐ring data are interpreted in the context of organization mandates and histories. We situate this study within a framework that examines the coproduction of science and policy, where scientists and resource managers collectively define and examine research and planning needs, the activities of which are embedded within wider social and political contexts. These findings have broader applications for understanding science‐policy interactions related to climate and climate change in resource management, and point to the potential benefits of reflexive interactions of scientists and decision makers.

Science be Dammed: How Ignoring Inconvenient Science Drained the Colorado River

University of Arizona Press | November 26th, 2019

Science Be Dammed is an alarming reminder of the high stakes in the management—and perils in the mismanagement—of water in the western United States.  It seems decep

Science Be Dammed is an alarming reminder of the high stakes in the management—and perils in the mismanagement—of water in the western United States.  It seems deceptively simple: even when clear evidence was available that the Colorado River could not sustain ambitious dreaming and planning by decision-makers throughout the twentieth century, river planners and political operatives irresponsibly made the least sustainable and most dangerous long-term decisions. Arguing that the science of the early twentieth century can shed new light on the mistakes at the heart of the over-allocation of the Colorado River, authors Eric Kuhn and John Fleck delve into rarely reported early studies, showing that scientists warned as early as the 1920s that there was not enough water for the farms and cities boosters wanted to build. Contrary to a common myth that the authors of the Colorado River Compact did the best they could with limited information, Kuhn and Fleck show that development boosters selectively chose the information needed to support their dreams, ignoring inconvenient science that suggested a more cautious approach. Today water managers are struggling to come to terms with the mistakes of the past. Focused on both science and policy, Kuhn and Fleck unravel the tangled web that has constructed the current crisis. With key decisions being made now, including negotiations for rules governing how the Colorado River water will be used after 2026, Science Be Dammed offers a clear-eyed path forward by looking back. Understanding how mistakes were made is crucial to understanding our contemporary problems. Science Be Dammed offers important lessons in the age of climate change about the necessity of seeking out the best science to support the decisions we make.

Securing Color River Supplies - An Urban-Agriculture Partnership in the Palo Verde Valley

Metropolitan Water District of Southern California (MWD) | March 16th, 2022

Severe sustained drought revisited managing the Colorado River system in times of water shortage 25 years later—Part II

American Water Resources Association (AWRA) | December 4th, 2022

Severe Sustained Drought Revisited: Managing the Colorado River System in Times of Water Shortage 25 Years Later — Part I

American Water Resources Association (AWRA) | September 20th, 2022

Shifting landscapes: decoupled urban irrigation and greenness patterns during severe drought

Environmental Research Letters (IOP) | June 7th, 2019

Urban outdoor water conservation and efficiency offer high potential for demand-side management, but irrigation, greenness, and climate interlinks must be better underst

Urban outdoor water conservation and efficiency offer high potential for demand-side management, but irrigation, greenness, and climate interlinks must be better understood to design optimal policies. To identify paired transitions during drought, we matched parcel-level water use data from smart, dedicated irrigation meters with high-spatial resolution, multispectral aerial imagery. We examined changes across 72 non-residential parcels using potable or recycled water for large landscape irrigation over four biennial summers (2010, 2012, 2014, and 2016) that encompassed a historic drought in California. We found that despite little change in irrigation levels during the first few years of the drought, parcel greenness deteriorated. Between summers 2010 and 2014, average parcel greenness decreased−61% for potable water irrigators and−56% for recycled water irrigators, providing evidence that vegetation could not reach its vigor from wetter, cooler years as the drought intensified with abnormally high temperatures. Between summers 2014–2016 as drought severity lessened, irrigation rates decreased significantly in line with high drought saliency, but greenness rebounded ubiquitously, on average+110% for potable water irrigators and+62% for recycled water irrigators, demonstrating climate-driven vegetation recovery as evaporation and plant evapotranspiration rates decreased. Transitions were similar for customers with both potable and recycled water; vegetation changes were dominated by the overarching climatic regime. As irrigation cannot always overcome drought conditions, which will become more severe under climate change, to maintain vegetation health, utilities and urban planners should consider the tradeoffs between providing green spaces and water scarcity. This includes evaluating the roles of climate-appropriate landscaping and adaptive reallocation of potable and recycled water resources to enhance water security. By addressing emerging themes in urban water management through analysis of data from forthcoming water metering and aerial imagery technologies, this research provides a unique perspective on water use, greenness, and drought linkages.

Shifts in MJO behavior enhance predictability of subseasonal precipitation whiplashes

Nature Portfolio (Springer Nature) | April 28th, 2025

Shrinking lakes, air pollution, and human health: Evidence from California's Salton Sea

Science of the Total Environment (Elsevier) | January 7th, 2020

Due to increased water withdrawals and ongoing climate change, many inland lakes around the world are shrinking and dry lake beds can be significant sources of particulat

Due to increased water withdrawals and ongoing climate change, many inland lakes around the world are shrinking and dry lake beds can be significant sources of particulate matter air pollution. Using a natural experiment provided by the shrinking Salton Sea in California, this paper shows that each one-foot drop in lake elevation is associated with a 0.28 μg/m3 (2.6%) increase in PM2.5 concentrations. IV model results then show that Salton Sea-induced changes in PM2.5 over 1998–2014 led to increases in respiratory mortality of 1.4/yr.–15.6/yr. in the counties surrounding the lake, generating $13.2–$147.3 million in annual health costs.

Sierra Nevada Regional Report - California’s Fourth Climate Change Assessment

California Natural Resources Agency (CNRA) | August 16th, 2018

The Sierra Nevada region is critical to the environment and economy of California. Its places and peoples provide essential natural resources including fresh wate

The Sierra Nevada region is critical to the environment and economy of California. Its places and peoples provide essential natural resources including fresh water, clean power, working lands, and famous wilderness. The region encompasses tremendous geographical, climatological, and ecological diversity that spans majestic mountains to deep desert basins. The climate consists of cool, wet winters and warm, dry summers with large differences due to latitude (e.g., the southern Sierra is snowier than northern Sierra) and topography (e.g., the Westside is wetter than the Eastside). Variability is another notable feature of the climate with the region experiencing some of the largest year-to-year climatic fluctuations in the United States. Herein we summarize our assessment of climate-change vulnerabilities and adaptation actions in the region.