NPDES Stormwater Cost Survey

California State Water Resources Control Board (SWRCB) | January 4th, 2005

Task A – Documenting Stormwater Program Costs  Five California municipalities and one metropolitan area with stormwater programs that are demonstrating meaningful

Task A – Documenting Stormwater Program Costs  Five California municipalities and one metropolitan area with stormwater programs that are demonstrating meaningful progress toward maximum extent practicable (MEP) compliance as identified by Regional Water Quality Control Board (RWQCB) staff were surveyed for the most recent stormwater compliance costs. Demonstrating meaningful progress is defined in this report as implementing activities specifically presented in the Storm Water Management Plans (SWMPs). Because permits use an iterative approach that increases requirements until water quality objectives are met, current levels of implementation may not be the ultimate MEP standard. This report does not address the benefits of permit compliance activities. Some scenarios addressing ultimate compliance cost are addressed in Task B. Task A was accomplished by the Office of Water Programs (OWP) at California State University, Sacramento (CSUS). Task B – Alternative Approaches to Stormwater Quality Control Task B is an assessment of regulatory policy to determine the intent of stormwater regulation regarding advanced treatment. Alternatives for stormwater quality control that are believed to comply with the intent of the regulations are described. Costs were estimated for the Los Angeles Regional Water Quality Control Board (LARWQCB) area. Task B was accomplished by the University of Southern California (USC) and the University of California at Los Angeles (UCLA).

Ocean submesoscale fronts induce diabatic heating and convective precipitation within storms

Nature Portfolio (Springer Nature) | January 30th, 2025

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to inte

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to intensify storms via latent heat release, the role of finer oceanic scales remains unknown. Using a global coupled ocean-atmosphere simulation at a km-scale resolution, we show that half of latent heat flux variability is driven by oceanic motions at the meso- ( ~ 40%) and submesoscale ( ~ 10-20 km-size,  < 10%) in the Kuroshio Extension during winter. Additionally, ocean submesoscale fronts, with temperature gradients of 5 °C per 10 km, induce a secondary circulation reaching 4 km within the troposphere, which enhances diabatic processes and convective precipitations within storms. In the warm sector of storms, ocean submesoscale fronts locally account for half the total precipitations, averaging 14 mm day−1 over five days. As such, ocean submesoscale fronts pump moisture from the ocean to the atmosphere and have the potential to affect storm intensification.

Ocean, Harbor and Bay Water Quality Report 2019-2020

Orange County Health Care Agency (OCHCA) | April 30th, 2021

The 2019–2020 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills and their impacts resulting in ocean water closures and provid

The 2019–2020 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills and their impacts resulting in ocean water closures and provides an analysis of bacteriological water quality data collected at Orange County’s (OC) ocean, harbor and bay waters.

Ocean, Harbor and Bay Water Quality Report 2023 – 2024

Orange County Health Care Agency (OCHCA) | May 30th, 2025

The 2023-2024 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills, the spill impacts resulting in ocean water closures and an analysis of ba

The 2023-2024 Ocean, Harbor and Bay Water Quality Report provides updated data on sewage spills, the spill impacts resulting in ocean water closures and an analysis of bacteriological water quality data collected at Orange County’s (OC) ocean, harbor and bay waters.

One Water LA 2040 Plan

City of Los Angeles | April 30th, 2018

The purpose of the One Water LA 2040 Plan (Plan) is to increase sustainable water management for the City of Los Angeles (City). The City launched One Water LA with two p

The purpose of the One Water LA 2040 Plan (Plan) is to increase sustainable water management for the City of Los Angeles (City). The City launched One Water LA with two primary goals: 1. Develop a vision and implementation strategy to more sustainably and cost-effectively manage water. 2. Identify ways for City departments and regional agencies to integrate their water management strategies. Los Angeles Sanitation (LASAN) and the Los Angeles Department of Water and Power (LADWP) led the Plan's development, partnering with other City departments, regional agencies, academia, the business community, and other stakeholders. The Plan provides a comprehensive strategy for managing water in a more integrated, collaborative, and sustainable way through new project, program, and policy opportunities. The Implementation Strategy provides a roadmap to make the One Water LA Vision a reality. Additional water projects, programs, or policies that are the sole responsibility of one agency, including LADWP's aqueduct or groundwater remediation project, are contained in each agency's appropriate plans. This plan is divided into an Executive Summary and ten sections. Executive Summary Volume One: Summary Report Volume Two: Wastewater Facilities Plan Volume Three: Stormwater and Urban Runoff Facilities Plan Volume Four: Los Angeles River Flow Study Volume Five: Integration Opportunities Analysis Volume Six: Climate Risk and Resilience Assessment for Wastewater and Stormwater Infrastructure Volume Seven: Implementation Strategy Supporting Documents Volume Eight: Technical Support Materials Volume Nine: Stakeholder Engagement Materials, Part 1, Part 2, Part 3 Volume Ten: Programmatic Environmental Impact Report (in progress)

Open data and stormwater systems in Los Angeles: applications for equitable green infrastructure

Local Environment (Taylor & Francis) | February 6th, 2018

Urban stormwater systems traditionally used “grey” infrastructure to manage runoff. Contemporary designs now incorporate “green” infrastructure, which offers addi

Urban stormwater systems traditionally used “grey” infrastructure to manage runoff. Contemporary designs now incorporate “green” infrastructure, which offers additional potential benefits such as urban amenities and health. Understanding how green and grey infrastructure investments are distributed across urban areas is important for new goals of promoting environmental justice in planning. In California, for instance, public investments increasingly require a percentage of funds to be spent in disadvantaged communities. Recent advancements in the availability of high-detail geographic data in cities can support prioritising investments to fulfil these multiple benefits. This paper analyses the distribution of stormwater infrastructure in Los Angeles (LA) County in relation to design criteria, urban structure and sociodemographic information. It demonstrates an approach for identifying projects that simultaneously address engineering needs and promote equity. Statistical analysis of high-detail sewer locations reveals geographic correlations with key local design parameters, urban characteristics and sociodemographic indicators. Watershed areas in LA County were identified that support multi-benefit projects, meeting dual criteria for infrastructure improvements and disadvantaged community status. As stormwater systems are increasingly designed for multi-benefit outcomes, new design frameworks can emphasise both performance and social equity.

Opportunities to Accelerate Nature-Based Solutions: A Roadmap for Climate Progress, Thriving Nature, Equity, and Prosperity

White House Domestic Climate Policy Office | November 30th, 2022

Optimal Selection and Placement of Green Infrastructure in Urban Watersheds for PCB Control

American Society of Civil Engineers (ASCE) | May 1st, 2019

San Francisco Bay and its watersheds are polluted by legacy polychlorinated biphenyls (PCBs), resulting in the establishment of a total maximum daily load (TDML) that req

San Francisco Bay and its watersheds are polluted by legacy polychlorinated biphenyls (PCBs), resulting in the establishment of a total maximum daily load (TDML) that requires a 90% PCB load reduction from municipal stormwater. Green infrastructure (GI) is a multibenefit solution for stormwater management, potentially addressing the TMDL objectives, but planning and implementing GI cost-effectively to achieve management goals remains a challenge and requires an integrated watershed approach. This study used the nondominated sorting genetic algorithm (NSGA-II) coupled with the Stormwater Management Model (SWMM) to find near-optimal combinations of GIs that maximize PCB load reduction and minimize total relative cost at a watershed scale. The selection and placement of three locally favored GI types (bioretention, infiltration trench, and permeable pavement) were analyzed based on their cost and effectiveness. The results show that between optimal solutions and nonoptimal solutions, the effectiveness in load reduction could vary as much as 30% and the difference in total relative cost could be well over $100 million. Sensitivity analysis of both GI costs and sizing criteria suggest that the assumptions made regarding these parameters greatly influenced the optimal solutions.

Optimizing sampling methods for monitoring pollutant trends in San Francisco Bay urban stormwater

San Francisco Estuary Institute (SFEI) | July 1st, 2016

The Small Tributaries Loading Strategy (STLS) focuses on urban stormwater loadings from small tributaries. To date, STLS monitoring has been geared towards dete

The Small Tributaries Loading Strategy (STLS) focuses on urban stormwater loadings from small tributaries. To date, STLS monitoring has been geared towards determining concentrations and annual loads of PCBs and Hg; the sampling approach has yet to be fully optimized for detecting trends over time. Here, we evaluate the variability and statistical power for detecting future trends in PCBs based on baseline STLS data in the Guadalupe River watershed. The objective was to improve our understanding of the influence of climatic and seasonal factors on baseline stormwater pollutant conditions, and inform refinements to the STLS monitoring design for detecting trends.

Origins of Extreme Climate States during the 1982–83 ENSO Winter

American Meteorological Society (AMS) | November 1st, 1997