Guadalupe River mercury concentrations and loads during the large rare January 2017 storm

San Francisco Estuary Institute (SFEI) | February 9th, 2018

The Guadalupe River watershed has a long history of urbanization and is the location of a historic mining district that produced 40 million kg of mercury (Hg) during ope

The Guadalupe River watershed has a long history of urbanization and is the location of a historic mining district that produced 40 million kg of mercury (Hg) during operation. The river system is listed as impaired and is a large pathway of Hg to San Francisco Bay. The TMDL calls for stakeholders to reduce load to an average of 9.4 kg per year over 20 years by removing H-laden wastes in the mining and urban areas and implementing other treatment practices. To demonstrate success, the stakeholders are documenting management efforts and have been conducting water sampling to show that average loads are decreasing or that Hg concentrations on suspended particles are trending towards the TMDL target of 0.2 mg/kg (dry wt., annual median). The Guadalupe River is capable of flows >10,000 cfs, and a flood flow of >6,000 cfs has a return interval of approximately 1:5 years yet most sampling has occurred at flows <4,000 cfs. Since most Hg is transported in the system during large storm events when Hg can be mobilized from the historic mining district, it is essential to measure the Hg load during these rare events. The main objective of this study was to sample and estimate loads during such a rare events.

Guide for Developing Onsite Water Systems to Support Regional Water Resilience

Pacific Institute | January 26th, 2023

Across the United States, urban communities face growing water challenges, from water scarcity to flooding, pollution, aging water infrastructure, and more. These challen

Across the United States, urban communities face growing water challenges, from water scarcity to flooding, pollution, aging water infrastructure, and more. These challenges present risks, but also an opportunity to rethink how we manage water, including adopting circular approaches in new buildings that reduce their water footprint and improve urban water resilience. Onsite water systems, for example, collect, treat, and reuse water from onsite sources, including wastewater, rainwater, and stormwater, for non-potable water uses like toilet flushing, outdoor irrigation, and cooling. Onsite water systems have the potential to provide multiple benefits for a site, water and wastewater systems, ecosystems, and communities. They can, for example, help companies mitigate water- related risks, like water shortages that threaten to disrupt business operations, and support corporate water stewardship goals. For communities, onsite water systems can enhance water supply reliability, improve water quality, reduce localized flooding, and increase urban green space. The realization and magnitude of benefits will vary with the type of system, scale of adoption, and other context-specific factors. This guide helps site developers consider how onsite water systems can be planned, designed, and operated to provide multiple benefits, and contribute to planning and designing onsite water systems that advance water resilience, support equity, support the environment, and protect public health at the site, water system, and community scales. For each of these outcomes, the guide provides sample questions to consider, stakeholders to engage, resources to examine, and analyses to perform.

Hacienda Avenue Bio-Infiltration Basins

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

Hourly storm characteristics along the U.S. West Coast: Role of atmospheric rivers in extreme precipitation

American Geophysical Union (AGU) | June 21st, 2017

Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation t

Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation totals. Despite generally lower hourly intensities, precipitation totals along the U.S. West Coast (USWC) are comparable to those in southeast U.S. (SEUS). Storm durations, more so than hourly intensities, strongly modulate precipitation-total variability over the USWC, where the correlation coefficients between storm durations and storm totals range from 0.7 to 0.9. Atmospheric rivers (ARs) contribute 30–50% of annual precipitation on the USWC and make such large contributions to extreme storms that 60–100% of the most extreme storms, i.e., storms with precipitation-total return intervals longer than 2 years, are associated with ARs. These extreme storm totals are more strongly tied to storm durations than to storm hourly or average intensities, emphasizing the importance of AR persistence to extreme storms on the USWC.

How freeing rivers can help California ease flood risks and revive ecosystems

Los Angeles Times | February 20th, 2024

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained

Natural floodplains — the lush green lands along rivers that historically flooded, retained water, and nourished life in the heart of the valley — were mostly drained and converted to farmland generations ago as the state’s waters were dammed and diverted. Today, an effort to bring back some of those floodplains is flourishing at the 2,100-acre Dos Rios Ranch Preserve near Modesto, where workers years ago planted native trees on retired farm fields and removed berms to create space for water to spread out again.

Hydrodynamic Simulations for Trash Loading in Southern California’s Dense Urbanized Watersheds

American Society of Civil Engineers (ASCE) | May 25th, 2024

Impact of underground storm drain systems on larval ecology of Culex and Aedes species in urban environments of Southern California

Nature Portfolio (Springer Nature) | July 16th, 2021

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant product

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant production habitats for mosquitoes. Knowledge of whether USDS habitats are suitable for newly introduced dengue vectors Aedes aegypti and Ae. albopictus will help guide surveillance and control efforts. To determine whether the USDS functions as a suitable larval habitat for Culex, Ae. aegypti and Ae. albopictus in southern California, we examined mosquito habitat utilization and larval survivorship using laboratory microcosm studies. The data showed that USDS constituted 4.1% of sampled larval habitats for Ae. aegypti and Ae. albopictus, and 22.0% for Cx. quinquefasciatus. Furthermore, USDS water collected in the summer completely inhibited Aedes larval development, but yielded a 15.0% pupation rate for Cx. quinquefasciatus. Food supplementation in the microcosms suggests that nutrient deficiency, toxins and other factors in the USDS water led to low success or complete failure of larval development. These results suggest that USDS habitats are currently not major productive larval habitats for Aedes mosquitoes in southern California. Our findings prompt inclusion of assessments of pupal productivity in USDS habitats and adult mosquito resting sites in the mosquito surveillance program.

Importance of subsurface water for hydrological response during storms in a post-wildfire bedrock landscape

Nature Portfolio (Springer Nature) | June 29th, 2023

LA Sustainable Water Project: Los Angeles City-Wide Overview

University of California, Los Angeles (UCLA) | February 1st, 2018

This report assesses the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local wat

This report assesses the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local water supplies for the City of Los Angeles (the City).  This final report summarizes the current practices and future opportunities at the City-owned Water Reclamation Plants and underlying groundwater basins and highlights the importance of considering all aspects of integrated water management even when dealing with water quality or supply-focused projects. Implementing watershed-scale best management practice programs to meet stormwater permit requirements will significantly improve water quality in all watersheds.  However, additional mechanisms such as increasing Low Impact Development implementation and comprehensive source tracking and source control mechanisms will be required to potentially eliminate water quality exceedances.  There are multiple efforts occurring in the City and the region to increase the recharge of recycled water into the ground and the volumes of remediated groundwater extracted. This research further assessed the impacts of potential water supply portfolios, with greater volumes of locally-supplied water, on GHG emissions and energy needs of supplying LA’s water.  Conservation will be another powerful tool to decrease our dependence on imported water.  This research demonstrates the complex interrelationships between all aspects of urban water management, including, for example, stormwater management and local water supply.

LA Sustainable Water Project: Los Angeles River Watershed

University of California, Los Angeles (UCLA) | September 1st, 2017

The LA Sustainable Water Project: Los Angeles River Watershed report explores the potential to improve water quality standards while integrating complementary One Water M

The LA Sustainable Water Project: Los Angeles River Watershed report explores the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local water supplies for the City of Los Angeles (the City) in the highly urbanized Los Angeles River (LAR) watershed.To assess the integrated water landscape in this watershed, the report also looks at current practices and future opportunities at the Donald C Tillman, LA Glendale, and Burbank Water Reclamation Plants (WRPs) and in the underlying Upper LA River Area (ULARA) adjudicated groundwater basins. Implementing watershed-scale best management practice programs to meet stormwater permit requirements will significantly improve water quality. However, additional mechanisms such as increasing Low Impact Development implementation and comprehensive source tracking and source control mechanisms will be required to potentially eliminate water quality exceedances. The 3 WRPs in the watershed currently discharge more than 30 million gallons per day of treated wastewater into the River; an increased focus on increasing local water supply could lead to a reduction in these discharges. The combination of increased stormwater capture and increased use of recycled water in the LAR watershed could lead to lower flows in the LAR and impact habitat and recreational uses; further study is needed to characterize potential impacts and identify optimal flows for the future of the LAR. The City is leading efforts in ULARA to increase the recharge of recycled water into theground by 30,000 acre feet per year and increase the volumes of remediated groundwater extracted by around 120,000 acre feet per year. This research demonstrates the complex interrelationships between all aspects of urban water management, including stormwater management and local water supply.