Los Angeles Basin Study The Future of Stormwater Conservation: Task 6 – Trade-Off Analysis & Opportunities

U.S. Bureau of Reclamation (USBR) | January 5th, 2016

The Los Angeles Basin Study (LA Basin Study) is a collaborative partnership between the Los Angeles County Flood Control District (LACFCD) and the U.S. Department of the

The Los Angeles Basin Study (LA Basin Study) is a collaborative partnership between the Los Angeles County Flood Control District (LACFCD) and the U.S. Department of the Interior, Bureau of Reclamation (Reclamation). The purpose of the LA Basin Study is to investigate long-range water conservation and flood risk impacts caused by projected changes in climate and population in the Los Angeles region. The LA Basin Study highlights opportunities for potential modifications and changes to both the existing regional stormwater capture system as well as for the development of new facilities and practices, which could help to resolve future water supply and flood risk issues. The stormwater capture concepts and alternatives developed in the Task 5 – Infrastructure & Operations Concepts report are evaluated in the trade-off analysis and opportunities highlighted in this report.  The primary purpose of Task 6 – Trade-Off Analysis & Opportunities is to evaluate the quantifiable and non-quantifiable benefits and costs of the stormwater concepts identified in the Task 5 report and to provide an analysis of the trade-offs among concepts. In most cases, various project concepts would generate benefits for some impact categories but not others, and would also impose various types of costs. The trade-off analysis provides a methodology for comparing different types of benefits and costs that cannot all be quantified in monetary terms. These trade-offs include economic, financial, environmental, and social effects. Economic effects include the benefits associated with different types of goods and services supported by the concepts, the costs of the different concepts, the impacts of the different concepts on the regional economy through changes in the amount and type of spending, and the cost effectiveness of different project concepts. Financial effects reflect the impacts of paying for a project, such as paying off capital debt and covering operation and maintenance expenses. Environmental effects reflect the type and quality of environmental and natural resources that would be potentially influenced by a concept. Environmental effects include items such as water quality, energy consumption, impacts on habitat, and ecosystem function. Social effects reflect how the concepts may alter the social characteristics of a community or region such as impacts to education, environmental justice, and quality of life.  Benefits are quantified for three categories of resource impacts. The first category is additional stormwater conserved or stored, which is measured in terms of acre-feet per year. The second is recreation, which is measured in miles of new trails. The third is increased habitat acreage and additional acquisition of right-of-way acreage that would provide habitat benefits. Stormwater conservation benefits are valued as improved water supply reliability, recreation is valued as a type of general recreation activity similar to outdoor activities at a local park, and habitat acreage is evaluated as an ecosystem improvement. In the case of the Regional Impact Programs concept, right-of-way acreage also produces some ecosystem benefits. Quantified benefits and costs as well as categories of qualitative benefits are summarized in Table ES-1. All benefits and costs are present valued over a 50-year planning period using the current Fiscal Year 2016 federal water project planning rate of 3.125%.  The economic analysis of quantified benefits can be used to evaluate the magnitude of potential benefits of each project group, recognizing that many additional benefits may exist that are not accounted for in a traditional benefit and cost analysis. It is important to note that quantified benefits could only be developed for a subset of the total beneficial effects associated with the concepts identified in the Task 5 report. There are many potential benefits associated with environmental and social improvements, flood risk mitigation, environmental justice, and other effects that could be large but cannot be evaluated quantitatively for this level of analysis. These unquantified benefits may be larger than quantified benefits in some cases and smaller in other cases. The intent of the qualitative assessment is to provide an indication of the potential magnitude of unquantified benefits. 

Los Angeles County Department of Public Works Hydrology Manual

Los Angeles County Department of Public Works (LACDPW) | January 30th, 2006

This manual establishes the Los Angeles County Department of Public Works' hydrologic design procedures and serves as a reference and training guide. This manual contains

This manual establishes the Los Angeles County Department of Public Works' hydrologic design procedures and serves as a reference and training guide. This manual contains charts, graphs, and tables necessary to conduct a hydrologic study within the County of Los Angeles. Examples provide guidance on using the hydrologic methods.

Los Angeles County’s Climate Cost Challenge

Center for Climate Integrity | April 2nd, 2024

Within the first two months of 2024, the City of Los Angeles had already exceeded its average annual rainfall, receiving nearly 15 inches of rain in back-to-back deluges.

Within the first two months of 2024, the City of Los Angeles had already exceeded its average annual rainfall, receiving nearly 15 inches of rain in back-to-back deluges.1 The storms flooded roads, brought massive wind gusts, ripped down trees, and killed nine people.2 The year prior was the hottest year ever recorded, including unseasonably hot weather into the fall months in Southern California. In October 2023, a wildfire ripped through rural lands southeast of the City of Los Angeles, destroying multiple buildings and forcing approximately 4,000 people to evacuate. With climate-driven disasters in Southern California growing more intense every year, it’s more important than ever for communities to invest in a growing range of climate adaptation and resilience projects. This study is the first-ever attempt to calculate the costs of preparing for and adapting to 14 different climate impacts on municipal, county, state, and federal governments in Los Angeles County.

Making Nature's City: A science-based framework for building urban biodiversity

San Francisco Estuary Institute (SFEI) | July 1st, 2019

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges th

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges threatens global biodiversity, and many species face potential extinction. While urban planners and conservationists have long treated these issues as distinct, there is growing evidence that cities not only harbor a significant fraction of the world’s biodiversity, but that they can also be made more livable and resilient for people, plants, and animals through nature-friendly urban design. Urban ecological science can provide a powerful tool to guide cities towards more biodiversity-friendly design. However, current research remains scattered across thousands of journal articles and largely inaccessible to practitioners. Making Nature’s City fills this gap, synthesizing global research to develop a science-based approach for supporting nature in cities. We identify seven key elements of urban form and function that work together to maximize biodiversity, and we illustrate these elements through a case study in California’s Silicon Valley. Using the framework developed in this report, urban designers and local residents can work together to link local parks, greenways, green roofs, street trees, stormwater basins, commercial landscaping, and backyards to support biodiversity while making cities better places to live. As we envision the healthier, and more resilient cities, Making Nature’s City provides practical guidance for the many actors who together will shape the nature of cities.

Managing Floods in California

Legislative Analyst's Office (LAO) | March 22nd, 2017

This report is intended to provide basic information about floods and flood management in California. (Whereas previous generations referred to “flood control” or “

This report is intended to provide basic information about floods and flood management in California. (Whereas previous generations referred to “flood control” or “flood prevention” activities, experts now prefer the term “flood management” in acknowledgement that floodwaters are recurring and inevitable.) We begin by summarizing the history, causes, and risk of floods across the state. We then describe flood management agencies, infrastructure, and strategies, as well as how governmental agencies typically respond when floods occur. Next, we describe the spending levels and funding sources currently supporting flood management efforts, as well as estimates for how much additional funding may be needed to improve those efforts. We conclude by highlighting some key challenges confronting the state in contemplating how best to manage floods in California.

Managing for Future Risks of Fire, Extreme Precipitation, and Post-fire Flooding

U.S. Bureau of Reclamation (USBR) | September 30th, 2016

On September 22–23, 2014, 23 scientists, resource managers, and urban planners convened in Las Vegas, Nevada, to discuss research and management needs related to seve

On September 22–23, 2014, 23 scientists, resource managers, and urban planners convened in Las Vegas, Nevada, to discuss research and management needs related to severe fires and post-fire flooding in the Intermountain West. The workshop was motivated by the concerns of water management agencies about the potential for a changing climate to exacerbate fire impacts through: 1) projected increases in acres burned; 2) potential changes in the intensity of future extreme precipitation; and 3) the frequency of extreme events, which the National Climate Assessment projects to at least double across the region. The workshop was convened by the University of Arizona with funding provided by the U.S. Bureau of Reclamation.

Marsh Sediment in Translation: A Review of Sediment Transport Across a Natural Tidal Salt Marsh in Northern San Francisco Bay

University of California, Davis (UC Davis) | March 15th, 2025

Deposition of inorganic sediment is essential for the sustainability of tidal salt marshes. Understanding variability in sediment sources and the processes of sediment de

Deposition of inorganic sediment is essential for the sustainability of tidal salt marshes. Understanding variability in sediment sources and the processes of sediment delivery to salt marshes are high priorities for decision-makers responsible for managing sediment and conserving and restoring marshes.

Memorandum Report on the Floods of January and February 1969 in the Southern District of the Department of Water Resources

California Department of Water Resources (DWR) | February 27th, 1970

Meteorological and geographical factors associated with dry lightning in central and northern California

Environmental Research: Climate (IOP) | August 8th, 2022

Lightning occurring with less than 2.5 mm of rainfall—typically referred to as ‘dry lightning’—is a major source of wildfire ignition in central and northern Cali

Lightning occurring with less than 2.5 mm of rainfall—typically referred to as ‘dry lightning’—is a major source of wildfire ignition in central and northern California. Despite being rare, dry lightning outbreaks have resulted in destructive fires in this region due to the intersection of dense, dry vegetation and a large population living adjacent to fire-prone lands. Since thunderstorms are much less common in this region relative to the interior West, the climatology and drivers of dry lightning have not been widely investigated in central and northern California. Using daily gridded lightning and precipitation observations (1987–2020) in combination with atmospheric reanalyses, we characterize the climatology of dry lightning and the associated meteorological conditions during the warm season (May–October) when wildfire risk is highest. Across the domain, nearly half (∼46%) of all cloud-to-ground lightning flashes occurred as dry lightning during the study period. We find that higher elevations (>2000 m) receive more dry lightning compared to lower elevations (

Methods Used to Update Ecosystem Restoration Maps Using New Digital Elevation Model and Tidal Data

Delta Stewardship Council (Delta Council) | June 29th, 2022