North Lahontan

Updating California Water Laws to Address Drought and Climate Change

California Planning & Conservation League Foundation | February 3rd, 2022

Urban and Agricultural Water Use in California, 1960–2015

Pacific Institute | June 22nd, 2020

Water is the lifeblood of California. It provides for the household needs of 40 million people. It generates electricity and cools power plants. It supports one of the mo

Water is the lifeblood of California. It provides for the household needs of 40 million people. It generates electricity and cools power plants. It supports one of the most productive agricultural regions in the world and various commercial and industrial activities, ultimately fueling the fifth largest economy in the world. Water is also critical to the health and viability of the state’s diverse aquatic and terrestrial ecosystems. This paper examines statewide urban and agricultural water-use trends from 1960 to 2015 using data from the California Department of Water Resources (DWR). We find that California has experienced a dramatic decoupling between water use and growth. Since 1967, California’s population has doubled, and its economic output has increased by a factor of five. Yet statewide water use increased by only 20 percent over this period due to improvements in urban and agricultural efficiency, as well as a shift to higher-value crops and less water-intensive commercial and industrial activities.  Despite positive signs, water use in California remains high. Across the state, rivers and streams are under stress from overuse, and groundwater is over-tapped. Climate change and continued growth are increasing pressure on the state’s water resources, including on water supply, demand, and quality. To address these challenges, we must continue and even expand efforts to improve the water-use efficiency of our homes, businesses, industries, and farms. Moreover, we urge the state to improve data collection and online systems to make data more easily, quickly, and readily available.

Urban Water Management Plan Guidebook

California Department of Water Resources (DWR) | January 30th, 2026

In 1983, the State of California Legislature (Legislature) enacted the Urban Water Management Planning Act (UWMP Act). The UWMP Act requires an urban water supplier (Supp

In 1983, the State of California Legislature (Legislature) enacted the Urban Water Management Planning Act (UWMP Act). The UWMP Act requires an urban water supplier (Supplier) providing water for municipal purposes to more than 3,000 customers or serving more than 3,000 acre-feet annually to adopt an Urban Water Management Plan (UWMP) every five years, demonstrating water supply reliability in normal, single dry, and multiple dry water years. The UWMP Act also requires the California Department of Water Resources (DWR) to report to the Legislature on the status of UWMPs. Appendix A contains copies of the UWMP Act and other sections of the California Water Code relevant to UWMPs. Appendix B shows revisions to the UWMP Act and to Water Code. There have been no requirement changes since 2020; only definitions have been added or updated. 

Walker River Atlas

California Department of Water Resources (DWR) | June 1st, 1992

The Walker River has its headwaters in California's high Sierras north of Mono Lake and terminates in a desert lake in Nevada. The Walker is a relatively small river

The Walker River has its headwaters in California's high Sierras north of Mono Lake and terminates in a desert lake in Nevada. The Walker is a relatively small river by California standards, in places resembling more stream than river, but is an important water source to arid western Nevada. The river's existence is best known to local residents and to devotees of trout fishing; travelers through the eastern Sierras are more apt to be familiar with the celebrated attractions of Lake Tahoe to the north and Mono Lake to the south.

Water Accounting in Western US, Australia, and Spain: Comparative Analysis

American Society of Civil Engineers (ASCE) | January 10th, 2020

Water Allocation in California - Legal Rights and Reform Needs

Golden Gate University (GSU) | March 31st, 1982

FOREWARD: Water supply, allocation, use and conservation are constantly debated in California, often appearing as highly charged political issues in candidates' races and

FOREWARD: Water supply, allocation, use and conservation are constantly debated in California, often appearing as highly charged political issues in candidates' races and on election ballots. This year is no exception, with major ballot propositions already scheduled for the June primary election and being circulated to qualify for the November general election. Accordingly this Research Paper on legal aspects of water allocation is being published for the valuable background it affords readers wishing to learn more about the subject. The author draws on his legal expertise, as well as his experience as Staff Director of the Governor's Commission to Review California Water Rights Law. The paper emphasizes the crucial role of water rights in California water management, and it points to the need for and present lack of a political consensus on water law reform. The author concludes by suggesting forces that could bring about interest-group realignments and other developments favorable to achieving the needed consensus on water law and management reform that so far has eluded Californians. Stanley Scott Assistant Director Institute of Governmental Studies March 1982

Water and Energy in California

Public Policy Institute of California (PPIC) | December 6th, 2022

Water Available for Replenishment 2018

California Department of Water Resources (DWR) | April 12th, 2018

Water Demand Projection Accuracy and Demand Management Trends in California Cities

American Geophysical Union (AGU) | November 21st, 2025

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppl

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppliers from 2000 to 2020. Through a systematic analysis of Urban Water Management Plans, we find that water suppliers consistently overestimated future demand by an average of 25% for 5-year projections and 74% for 20-year projections. This overestimation stems primarily from assumptions about per capita water demand rather than population growth estimates. While suppliers generally projected stable or increasing per capita demand, actual water demand per capita declined by 1.9% annually between 2000 and 2020, leading to a decoupling of water demand from population growth. Concurrently, we document a substantial increase in water demand management incentives, with non-voluntary regulations emerging as the dominant demand management approach by 2020, largely driven by state policies like the Model Water Efficient Landscape Ordinance and California Green Building Standards. Demand management efforts have evolved from primarily indoor and educational initiatives toward outdoor-focused non-voluntary regulations and rebates. This shift appears closely linked to the reduction in per capita demand that suppliers failed to fully capture in their water demand projections. Our findings underscore the importance of incorporating dynamic conservation trends into demand projections and suggest that suppliers should develop more sophisticated forecasting methods that account for the continuing evolution of water efficiency incentives. This research provides valuable insights for water resource planners seeking to improve the accuracy of water demand projections in an era of increasing conservation and climate uncertainty.

Water Quality Control Plan for the Lahontan region

Lahontan Regional Water Quality Control Board (LRWQCB) | December 15th, 2015

Water quality standards and control measures for surface and ground waters of the Lahontan Region are contained in the Water Quality Control Plan for the Lahontan Region

Water quality standards and control measures for surface and ground waters of the Lahontan Region are contained in the Water Quality Control Plan for the Lahontan Region (Basin Plan). The plan designates beneficial uses for water bodies and establishes water quality objectives, waste discharge prohibitions, and other implementation measures to protect those beneficial uses. State water quality standards also include a Nondegradation Policy. Water quality control measures include Total Maximum Daily Loads (TMDLs), which are often, but not always, adopted as Basin Plan amendments. See the Lahontan Water Board’s TMDL Program web page for further information. The Lahontan Basin plan took effect in 1995, replacing three earlier plans. The current edition of the plan includes fully approved sets of amendments adopted since 1995. Chapters and sections of the plan are available in separate files to facilitate downloading. In addition to the state standards in the Basin Plan, federal water quality standards for certain toxic pollutants apply to surface waters within California, including the Lahontan Region. These standards are contained in the National Toxics Rule (40 CFR 131.36) and the California Toxics Rule (40 CFR 131.37). The California State Water Resources Control Board (SWRCB) has adopted a statewide implementation policy for the federal toxics standards, including summary tables listing the standards themselves. The federal standards have not yet been physically incorporated into the Basin Plan. The National Toxics Rule and California Toxics Rule standards differ from federal water quality criteria in that they are enforceable. Federal criteria are non-enforceable, science-based thresholds that can be used in development of enforceable state water quality standards. For the latest information on this water quality control plan, including any amendments, click here.