The Cost of Rehabilitating Dams in the U.S.

Association of State Dam Safety Officials (ASDSO) | August 7th, 2025

In 2022, the ASDSO Board of Directors established a task force to review and update the methodology and processes that were developed several years earlier by ASDSO to es

In 2022, the ASDSO Board of Directors established a task force to review and update the methodology and processes that were developed several years earlier by ASDSO to estimate the costs to rehabilitate non-federal dams in the United States (U.S.). This was a one-year project financed by ASDSO. The updated methodology and processes used readily available data to estimate the number of dams in need of rehabilitation based on dam height, age, and Condition Assessment rating. Data from more than 500 dam rehabilitation projects nationwide, ranging from $10,000 to more than $500 million, was used in determining the total amount of funding needed for dam rehabilitation at a national level. The purpose of this report is to inform national and state policy decisions and provide the public and the media with a high-level understanding of the national dam rehabilitation need in terms of estimated costs. The findings and methodologies are not meant to be used to estimate a specific dam rehabilitation cost.

The critical role of humidity in modeling summer electricity demand across the United States

Nature Portfolio (Springer Nature) | April 3rd, 2020

Cooling demand is projected to increase under climate change. However, most of the existing projections are based on rising air temperatures alone, ignoring that

Cooling demand is projected to increase under climate change. However, most of the existing projections are based on rising air temperatures alone, ignoring that rising temperatures are associated with increased humidity; a lethal combination that could significantly increase morbidity and mortality rates during extreme heat events. We bridge this gap by identifying the key measures of heat stress, considering both air temperature and near-surface humidity, in characterizing the climate sensitivity of electricity demand at a national scale. Here we show that in many of the high energy consuming states, such as California and Texas, projections based on air temperature alone underestimates cooling demand by as much as 10–15% under both present and future climate scenarios. Our results establish that air temperature is a necessary but not sufficient variable for adequately characterizing the climate sensitivity of cooling load, and that near-surface humidity plays an equally important role.

The Decline of Striped Bass in the Sacramento-San Joaquin Estuary, California

American Fisheries Society (AFS) | July 1st, 1985

The abundance of young striped bass Morone saxatilis in the Sacramento-San Joaquin Estuary has suffered an unsteady but persistent decline from population levels that wer

The abundance of young striped bass Morone saxatilis in the Sacramento-San Joaquin Estuary has suffered an unsteady but persistent decline from population levels that were high in the middle 1960s. The decline was particularly severe in 1977 and abundance of young striped bass has been low every subsequent year. The adult striped bass population also has fallen during the past 20 years, but the exact period over which the decline occurred and the rate of decline are not clear. The adult population is now about one-quarter of its former size and there is little sign of recovery. We believe the Sacramento-San Joaquin striped bass population and the fishery that it supports are in serious danger. The cause is most likely one or more of four factors. (1) The adult population is now so low that egg production may be inadequate. (2) The plankton food supply of young striped bass in the western Sacramento-San Joaquin Delta and Suisun Bay has been greatly reduced each spring. Diversion of water from the delta for agricultural purposes is a prime suspect for the decrease in food production. (3) Large numbers of young fish are lost by entrainment in water diversions. (4) The population is stressed by toxic substances such as petrochemicals and pesticides. Additional studies are underway to help determine the principal cause(s) of the striped bass decline.

The Definition of Environmental Justice and the Designation of the California Office of Planning and Research as Coordinating Agency for Environmental Justice

State of California | November 18th, 2019

The Delta as Changing Landscapes

University of California, Davis (UC Davis) | July 1st, 2016

What happens at one place in a landscape influences and is influenced by what happens in other places. Consequently, management and restoration that focus on individual p

What happens at one place in a landscape influences and is influenced by what happens in other places. Consequently, management and restoration that focus on individual places may fail to recognize and incorporate interactions across entire landscapes. The science of landscape ecology, which emphasizes the interplay of landscape structure, function, and change at multiple scales, offers a perspective that can integrate the spatial relationships of ecological processes and the functional interconnections of land and water in the Delta. Although the Delta is one of the most studied estuaries in the world, applications of landscape science have been limited. We describe why it is important to incorporate landscape science into management and restoration, emphasizing how Delta landscapes have changed over the past centuries. The land–water linkages of the past have been broken, waterways have been over-connected, and hard boundaries have replaced the gradual and dynamic transitions among landscape patches. The contemporary landscape also has new, novel assemblages of species and stressors that were not there in the past. This historical perspective indicates how knowledge of past landscape functions can contribute to the restoration and management of contemporary landscapes. We illustrate these points with case studies of inundation dynamics and riparian woodlands, and use a third example to describe a landscape approach to restoration. We propose that science that encompasses the multiple, interacting components of functional landscapes in the Delta will foster resilient and enduring restoration and management outcomes that benefit both people and wildlife. We suggest several ways of moving landscape science to the forefront of management and restoration in the Delta.

The Delta on Fast Forward - Thinking Beyond the Next Crisis (Summary for Policymakers of the State of Bay Delta Science 2016)

University of California, Davis (UC Davis) | December 1st, 2016

Delta science needs to push beyond its tendency to focus on short-term policy mandates and near-term crises. Taking a longer, 50- to 100-year viewpoint has been part of v

Delta science needs to push beyond its tendency to focus on short-term policy mandates and near-term crises. Taking a longer, 50- to 100-year viewpoint has been part of various planning exercises including Delta Vision. That kind of long-range thinking now needs to be more strongly incorporated into the whole Delta science and management endeavor. An appreciation of the changes that are coming, particularly those associated with climate change, needs to inform all our research and planning. In the meantime, despite management actions that in some instances appear heroic, native fish continue to decline in the Delta. The food web has changed dramatically, new stressors are added daily to existing ones, and several native species are virtually extinct. While we must continue to try to shore up the delta smelt, for example, it is time for serious debate about more radical alternatives to habitat restoration, including assisted relocation, assisted evolution, even perhaps cryopreservation (freezing of genetic materials). Agency mandates based on the past should not prevent us from taking actions that prepare us for a very different future. The capacity of the Delta to absorb extremes of all kinds is declining. In the future, water managers will have to adjust to reduced and more variable inflows to the Delta and to less predictable sources of water supply. Sustaining a Delta ecosystem hospitable to native species will be much more difficult. In that case, it may become necessary to refocus on managing for novel plant and animal communities that provide desirable ecosystem services. Delaying action until the next crisis is upon us will greatly increase the risk and costs of failure.

The Delta on Fast Forward: Thinking Beyond the Next Crisis

CALFED | September 1st, 2016

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 Delta Pool

State of California | January 2nd, 1961