Planned operation of large-scale water-distribution system

American Society of Civil Engineers (ASCE) | May 1st, 1995

A water-supply-distribution-system planning model has been developed using a directed graph algorithm as its pre- and post-processors and a linear programming (LP) proced

A water-supply-distribution-system planning model has been developed using a directed graph algorithm as its pre- and post-processors and a linear programming (LP) procedure as an “intelligent” system operator at its core. The directed graph, as a preprocessor, is used to produce a mathematical representation of the distribution system in question, to check the consistency and correctness of the network topology before an input file is created for the LP procedure. In the postprocessing mode, the directed graph generates files for graphical displays of model results and performs graph analyses such as depth- and breadth-first traversals, cut-set and connectivity for evaluating water-quality blending, tracking of source-to-demand contributions, system reliability, and lifeline objectives. Unlike the conventional formulation of a resource-allocation problem, the demand requirements, storage capacities, and other system constraints are removed from the constraint set and translated into a composite objective function. This methodology was successfully applied to the Metropolitan Water District of Southern California's (MWD's) distribution system. The results indicate that the combination of using an LP procedure and graph algorithm is a very versatile tool for solving large-scale water-distribution problems. This paper documents the concept used in developing the system-planning model and the results of its application to a simplified example as well as application to four case studies involving the entire MWD's distribution system.

Plumbing the Depths: Californians Without Toilets and Running Water

Pacific Institute | July 15th, 2019

California’s Human Right to Water law states that “every human being has the right to safe, clean, affordable, and accessible water adequate for human consumption

California’s Human Right to Water law states that “every human being has the right to safe, clean, affordable, and accessible water adequate for human consumption, cooking, and sanitary purposes.” To date, the policy discussion on meeting California’s Human Right to Water has focused largely on expanding and improving drinking water utility services in the state, and improving the quality and reliability of drinking water for rural households using domestic wells. Sanitation and wastewater have received less attention. There also has been less attention paid to individuals and households in communities served by functional water and wastewater utilities but lacking the plumbing necessary to access those services. To partially remedy these gaps, we set out to better understand the number of Californians with inadequate access to toilets and hot and cold running water.

Policy for Water Quality Control for Recycled Water (Recycled Water Policy)

California State Water Resources Control Board (SWRCB) | June 21st, 2013

The purpose of this Policy is to increase the use of recycled water from municipal wastewater sources that meets the definition in Water Code section 13050(n), in a manne

The purpose of this Policy is to increase the use of recycled water from municipal wastewater sources that meets the definition in Water Code section 13050(n), in a manner that implements state and federal water quality laws. The State Water Board expects to develop additional policies to encourage the use of stormwater, encourage water conservation, encourage the conjunctive use of surface and groundwater, and improve the use of local water supplies. When used in compliance with this Policy, Title 22 and all applicable state and federal water quality laws, the State Water Board finds that recycled water is safe for approved uses, and strongly supports recycled water as a safe alternative to potable water for such approved uses.

Post-2026 Operational Guidelines and Strategies for Lake Powell and Lake Mead – Draft Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | January 16th, 2026

The Secretary of the Department of the Interior, acting through the Bureau of Reclamation, proposes the adoption of new guidelines and coordinated management strategies t

The Secretary of the Department of the Interior, acting through the Bureau of Reclamation, proposes the adoption of new guidelines and coordinated management strategies to address Lake Powell and Lake Mead through their full operating range to take effect when the current agreements expire in 2026. Management strategies will primarily focus on the operation of Glen Canyon Dam and Hoover Dam, but may include actions upstream and downstream of these facilities to protect critical reservoir elevations. This Draft EIS has been prepared to inform the Secretary’s timely adoption of a new set of guidelines that would be sufficiently robust and provide improved predictability to all water users and managers in the Colorado River Basin. This Draft EIS has been prepared pursuant to the National Environmental Policy Act to address the formulation and evaluation of specific interim criteria and to identify the potential environmental impacts of implementing such criteria.

Potential Effects of Groundwater Pumping on Water Levels, Phreatophytes, and Spring Discharges in Spring and Snake Valleys, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

U.S. Geological Survey (USGS) | March 18th, 2011

PPIC Statewide Survey: Californians and the Environment

Public Policy Institute of California (PPIC) | August 8th, 2024

Californians have been facing a record heat wave and wildfires across the state this summer. The state’s multibillion-dollar budget deficit prompted spending cuts for

Californians have been facing a record heat wave and wildfires across the state this summer. The state’s multibillion-dollar budget deficit prompted spending cuts for climate and energy programs. In response, the legislature approved a $10 billion state bond for the November ballot that asks voters to approve more funding for drought, floods, wildfires, coastal resilience, and extreme heat mitigation. The deep partisan divide on climate and energy policies surfaced in the presidential debate on June 27. These are the key findings of the Californians and the Environment survey on local, state, and national issues and coastal and inland topics that was conducted June 24–July 2, 2024.

Precipitation History of the Mojave Desert Region, 1893–2001

U.S. Geological Survey (USGS) | July 1st, 2004

The Mojave Desert region covers 152,000 square km of the Southwestern United States. Recent studies by U.S. Geological Survey (USGS) and other scientists suggest

The Mojave Desert region covers 152,000 square km of the Southwestern United States. Recent studies by U.S. Geological Survey (USGS) and other scientists suggest that the region may become drier for the next 2 to 3 decades, in a pattern similar to mid-20th century dry conditions. Because the region’s population has increased rapidly since the mid-1950s, a repeat of such a dry episode could have severe consequences not only for residents but also for the desert’s diverse and fragile ecosystems.

Precipitation in a warming world: Assessing projected hydro-climate changes in California and other Mediterranean climate regions

Nature Portfolio (Springer Nature) | September 7th, 2017

In most Mediterranean climate (MedClim) regions around the world, global climate models (GCMs) consistently project drier futures. In California, however, proj

In most Mediterranean climate (MedClim) regions around the world, global climate models (GCMs) consistently project drier futures. In California, however, projections of changes in annual precipitation are inconsistent. Analysis of daily precipitation in 30 GCMs reveals patterns in projected hydrometeorology over each of the five MedClm regions globally and helps disentangle their causes. MedClim regions, except California, are expected to dry via decreased frequency of winter precipitation. Frequencies of extreme precipitation, however, are projected to increase over the two MedClim regions of the Northern Hemisphere where projected warming is strongest. The increase in heavy and extreme precipitation is particularly robust over California, where it is only partially offset by projected decreases in low-medium intensity precipitation. Over the Mediterranean Basin, however, losses from decreasing frequency of low-medium-intensity precipitation are projected to dominate gains from intensifying projected extreme precipitation. MedClim regions are projected to become more sub-tropical, i.e. made dryer via pole-ward expanding subtropical subsidence. California’s more nuanced hydrological future reflects a precarious balance between the expanding subtropical high from the south and the south-eastward extending Aleutian low from the north-west. These dynamical mechanisms and thermodynamic moistening of the warming atmosphere result in increased horizontal water vapor transport, bolstering extreme precipitation events.

Precipitation in a warming world: Assessing projected hydro‐climate changes in California and other Mediterranean climate regions

Nature Portfolio (Springer Nature) | September 7th, 2017

In most Mediterranean climate (MedClim) regions around the world, global climate models (GCMs) consistently project drier futures. In California, however, proj

In most Mediterranean climate (MedClim) regions around the world, global climate models (GCMs) consistently project drier futures. In California, however, projections of changes in annual precipitation are inconsistent. Analysis of daily precipitation in 30 GCMs reveals patterns in projected hydrometeorology over each of the five MedClm regions globally and helps disentangle their causes. MedClim regions, except California, are expected to dry via decreased frequency of winter precipitation. Frequencies of extreme precipitation, however, are projected to increase over the two MedClim regions of the Northern Hemisphere where projected warming is strongest. The increase in heavy and extreme precipitation is particularly robust over California, where it is only partially offset by projected decreases in low-medium intensity precipitation. Over the Mediterranean Basin, however, losses from decreasing frequency of low-medium-intensity precipitation are projected to dominate gains from intensifying projected extreme precipitation. MedClim regions are projected to become more sub-tropical, i.e. made dryer via pole-ward expanding subtropical subsidence. California’s more nuanced hydrological future reflects a precarious balance between the expanding subtropical high from the south and the south-eastward extending Aleutian low from the north-west. These dynamical mechanisms and thermodynamic moistening of the warming atmosphere result in increased horizontal water vapor transport, bolstering extreme precipitation events.

Precipitation Regime Change in Western North America: the Role of Atmospheric Rivers

Nature Portfolio (Springer Nature) | July 9th, 2019

Daily precipitation in California has been projected to become less frequent even as precipitation extremes intensify, leading to uncertainty in the overall re

Daily precipitation in California has been projected to become less frequent even as precipitation extremes intensify, leading to uncertainty in the overall response to climate warming. Precipitation extremes are historically associated with Atmospheric Rivers (ARs). Sixteen global climate modelsare evaluated for realism in modeled historical AR behavior and contribution of the resulting dailyprecipitation to annual total precipitation over Western North America. The five most realistic models display consistent changes in future AR behavior, constraining the spread of the full ensemble. They, moreover, project increasing year-to-year variability of total annual precipitation, particularly over California, where change in total annual precipitation is not projected with confidence. Focusing on three representative river basins along the West Coast, we show that, while the decrease in precipitation frequency is mostly due to non-AR events, the increase in heavy and extreme precipitation is almost entirely due to ARs. This research demonstrates that examining meteorological causes of precipitation regime change can lead to better and more nuanced understanding of climate projections. It highlights the critical role of future changes in ARs to Western water resources, especially over California.