The 1922 Compact is Now the Obvious Elephant in the Negotiating Room

John Fleck | October 6th, 2025

The California Water Atlas

Governor's Office of Planning and Research (OPR) | October 24th, 1979

This book sets out to tell the biggest story in the richest and most populous state in the Union. Water lies at the basis of the modern prosperity of California, and th

This book sets out to tell the biggest story in the richest and most populous state in the Union. Water lies at the basis of the modern prosperity of California, and the history of the state is in large part the history of water development. The problems of water supply and delivery for the future are emerging among the critical issues facing not only California but the entire American Southwest over the next ten years. And yet, at a time when environmental consciousness is high and complex problems of world energy supply and international finance are part of the normal fare in our daily newspapers, water remains probably the least popularly understood of our natural resources. For a higher resolution copy, click here to be taken to Digital Commons of California State University, Monterey Bay

The California Water Plan: Projected Use and Available Water Supplies to 2010

California Department of Water Resources (DWR) | December 15th, 1983

The Case of Shifting Snow

Climate Central | February 5th, 2020

Whether you live among palm trees or pine trees, snow plays a critical role in our climate. Snow keeps our planet cooler, significantly affects water resources, and is a

Whether you live among palm trees or pine trees, snow plays a critical role in our climate. Snow keeps our planet cooler, significantly affects water resources, and is a revealing indicator of climate change. Forecasting snowfall and determining long-term trends of snow climatology are inherently challenging, but the research team at Climate Central has produced an analysis of snowfall trends across the United States. While no single overall national trend in snowfall can be discerned from the results, clear regional and seasonal patterns do emerge. In almost all areas of the country, snow is decreasing in the “shoulder” seasons—fall and spring. Results from 145 locations show that 116 stations (80%) had decreased snowfall before December, and 96 stations (66%) had decreased snowfall after March 1. Winter showed a mixed record, with more snow in northern climates, and decreasing snow in the southern regions. We also compared total snowfall from the 1970s to the 2010s and ranked the 20 cities with the biggest percentage gains and losses, using endpoint analysis. The changing patterns of how much, when, and where snow falls have significant impacts on our climate, our economy, and our lives. This report provides a primer on the climatology of snow and includes resources on how to report on snow—or the lack of it—in your area.

The challenge of closing the climate adaptation gap for water supply utilities

Nature Portfolio (Springer Nature) | June 29th, 2024

The Cost of Alternative Water Supply and Efficiency Options in California

Pacific Institute | October 13th, 2016

The Cost of Alternative Water Supply and Efficiency Options in California is the first comprehensive analysis to examine the cost of various strategies throughout the sta

The Cost of Alternative Water Supply and Efficiency Options in California is the first comprehensive analysis to examine the cost of various strategies throughout the state to augment local water supplies and reduce water demand in urban areas. The study uses methods developed in the field of energy economics to determine the “levelized” costs of each supply and demand management option. The study finds that the cost of new supplies in California is highly varied. Large stormwater capture projects are among the least expensive of the water supplies examined, with a median cost of about $590 per acre-foot. By contrast, seawater desalination, with a median cost of $2,100 per acre-foot for large projects and $2,800 per acre-foot for smaller projects, is among the most expensive water supply option. Brackish water desalination is much less expensive due to lower energy and treatment costs. Generally, the cost of recycled water is in between that of stormwater capture and seawater desalination. Non-potable reuse – which treats water for irrigation and other non-drinking purposes – is typically less expensive than indirect potable reuse due to the lower treatment requirements; however, the cost of building or expanding a separate “purple pipe” distribution system to deliver non-potable water may be such that indirect potable reuse could be more cost effective. Nonetheless, the study finds that urban water conservation and efficiency are the most cost-effective ways to meet current and future water needs. Indeed, many residential and non-residential measures have a “negative cost,” which means that they save the customer more money over their lifetime than they cost to implement.

The Delta Plan

Delta Stewardship Council (Delta Council) | May 16th, 2013

The Delta Plan is a comprehensive, long-term management plan for the Delta. Required by the 2009 Delta Reform Act, it creates new rules and recommendations to further the

The Delta Plan is a comprehensive, long-term management plan for the Delta. Required by the 2009 Delta Reform Act, it creates new rules and recommendations to further the state’s coequal goals for the Delta: Improve statewide water supply reliability, and protect and restore a vibrant and healthy Delta ecosystem, all in a manner that preserves, protects and enhances the unique agricultural, cultural, and recreational characteristics of the Delta. Now the Council is considering updates to the Delta Plan. For information about the amendment process, please click here. Developed through eights drafts, hundreds of hours of public meetings and thousands of public comments over two years, the Delta Plan is guided by the best available science and is founded on cooperation and coordination among federal, State and local agencies. The Delta Plan is enforceable through regulatory authority in the Delta Reform Act that requires state and local agencies to be consistent with the Delta Plan. The Delta Plan was unanimously adopted by the Delta Stewardship Council on May 16, 2013. Subsequently its 14 regulatory policies were approved by the Office of Administrative Law, a state agency that ensures the regulations are clear, necessary, legally valid, and available to the public. The Delta Plan became effective with legally-enforceable regulations on September 1, 2013.

The Delta Plan: Ensuring a reliable water supply for California, a healthy Delta ecosystem, and a place of enduring value

Delta Stewardship Council (Delta Council) | May 16th, 2013

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in a maze of controversy. The Delta is a zone where the wants of a modern society come into collision with each other and with the stubborn limitations of a natural system. In 2009, seeking an end to decades of conflict over water, the Legislature established the Delta Stewardship Council with a mandate to resolve long-standing issues. The first step toward that resolution is the document you have before you, the Delta Plan.

The economic value of local water supplies in Los Angeles

Nature Portfolio (Springer Nature) | May 21st, 2018

Los Angeles imports water over long distances to supplement local supplies. Reduced reliability of the available imports is driving many local agencies to promote conserv

Los Angeles imports water over long distances to supplement local supplies. Reduced reliability of the available imports is driving many local agencies to promote conservation and enhance local water sources. These include stormwater capture, water reuse and groundwater. But financial considerations are often a significant impediment to project development, especially when comparing new and existing sources. Here we demonstrate a comprehensive approach for evaluating the economic implications of shifting to local water reliance in Los Angeles County. We show that local water supplies are economically competitive. Results from integrated hydroeconomic modelling of urban water in Los Angeles identify cost-effective water supply portfolios and conservation targets. Considering costs across the ‘full-cycles’ of urban water supply that span agency boundaries yields better comparisons of planning alternatives. Throughout the region, many water retailers could successfully mitigate effects of imported water cuts while still supporting drought-tolerant landscapes, but some would suffer due to over-reliance on imports. Updating economic assessment methods would support needed innovations to achieve local reliance in Los Angeles, including infrastructure investments, institutional reforms, many more drought-tolerant landscapes and reallocated groundwater rights.

The effect of reducing per capita water and energy uses on renewable water resources in the water, food and energy nexus

Nature Portfolio (Springer Nature) | May 9th, 2022

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantit

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantitative environmental water needs. Surface and groundwater resources are considered jointly in the water resources subsystem of this dynamic system. The developed model considers the effects of reducing the per capita use water and energy on its system’s components. Results indicate that due to feedbacks the changes in per capita uses of water and energy have indirect and direct effects. About 40% of the total water savings achieved by the per capita change policy was related to energy savings, in other words, it is an indirect saving. Implementation of per capita use reductions compensates for 9% of the decline of Iran’s groundwater reservoirs (non-renewable resources in the short term) that occur during the five-year study period. The Manageable and Exploitable Renewable Water Stress Index (MRWI) corresponding to water and energy savings equals 214.5%, which is better than its value under the current situation (which is equal to 235.1%).