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.

Order Approving Temporary Urgency Changes to Water Right License and Permit Terms Relating to Delta Water Quality Objectives

California State Water Resources Control Board (SWRCB) | February 21st, 2023

Ordinary High Flows and the Stage–Discharge Relationship in the Arid West Region

U.S. Army Corps of Engineers (USACE) | July 14th, 2011

The Ordinary High Water Mark (OHWM) defines the lateral extent of non-wetland waters and is regulated as “Waters of the United States” under Sec. 404 of the Clean Wat

The Ordinary High Water Mark (OHWM) defines the lateral extent of non-wetland waters and is regulated as “Waters of the United States” under Sec. 404 of the Clean Water Act. Previous research has developed a reliable and repeatable methodology for identifying the OHWM on ephemeral and intermittent streams in the Arid West using the physical features of the channel (Lichvar and McColley 2008, Curtis and Lichvar 2010). This study expands upon the previous reports by providing an analysis of how gage data may be utilized in OHW determinations. We clarify the methodology for using gage data, review the potential errors encountered in developing a stage–discharge relationship, compare the position of the gage-predicted OHWM to the field OHW signature, and determine the recurrence interval and flow duration of OHW events. The field OHW signature often is not associated with a 2-year flood event like many assume, but ranges from <1- to 15.5-year flood event. This large variation in recurrence intervals for the field OHWMs makes it impossible to define the frequency of the ordinary high flow from gage data because the OHW event is unique to each channel.

Organic Chemical Contaminants in Water System Infrastructure Following Wildfire

American Chemical Society (ACS) | February 1st, 2022

Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile o

Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile organic compounds (VOCs) were found in public drinking water systems in fire-affected areas. The sources of the contamination and appropriate remediation have been urgent matters of investigation. This study characterizes target and nontarget VOCs and semivolatile organic compounds (SVOCs) in water from a highly contaminated service line after the 2018 Camp Fire (Paradise, CA). Ninety-five organic compounds were identified or tentatively identified in the service line. Laboratory combustion experiments with drinking water pipes made of polyvinyl chloride (PVC), cross-linked polyethylene, and high-density polyethylene and a review of the literature were used to evaluate potential sources of the detected chemicals. Among the service line contaminants were 32 compounds associated with PVC pyrolysis and 28 organic compounds also associated with the pyrolysis of polyethylene. The service line sample also contained 55 compounds associated with uncontrolled burning of biomass and waste materials. The findings support hypotheses that wildfires can contaminate drinking water systems both by thermal damage to plastic pipes and intrusion of smoke. Residual chlorine disinfectants in the water system modify the contaminant distribution observed.

Organic geochemistry and toxicology of a stream impacted by unconventional oil and gas wastewater disposal operations

Applied Geochemistry (Elsevier) | March 10th, 2017

The large volume of wastewater produced during unconventional oil and gas (UOG) extraction is a significant challenge for the energy industry and of environmental concern

The large volume of wastewater produced during unconventional oil and gas (UOG) extraction is a significant challenge for the energy industry and of environmental concern, as the risks due to leaks, spills, and migration of these fluids into natural waters are unknown. UOG wastewater is often hypersaline, and contains myriad organic and inorganic substances added for production purposes and derived from the source rock or formation water. In this study, we examined the organic composition and toxicology of water and sediments in a stream adjacent to an underground injection disposal facility that handles UOG wastewaters.

Origin of methane and sources of high concentrations in Los Angeles groundwater

American Geophysical Union (AGU) | February 12th, 2018

High dissolved methane gas concentrations were measured in 37 groundwater samples collected in the Los Angeles Basin, California. The origin of the methane was identified

High dissolved methane gas concentrations were measured in 37 groundwater samples collected in the Los Angeles Basin, California. The origin of the methane was identified as microbial activity rather than from the burial and heating of organic material. The source of the methane was microbial production in shallow, oxygen-depleted aquifers rather than the upward migration or leakage of methane associated with oil fields in the basin.

Over‐pumping leads to California groundwater arsenic threat

Nature Portfolio (Springer Nature) | June 5th, 2018

Water resources are being challenged to meet domestic, agricultural, and industrial needs. To complement finite surface water supplies that are being stressed b

Water resources are being challenged to meet domestic, agricultural, and industrial needs. To complement finite surface water supplies that are being stressed by changes in precipitation and increased demand, groundwater is increasingly being used. Sustaining groundwater use requires considering both water quantity and quality. A unique challenge for groundwater use, as compared with surface water, is the presence of naturally occurring contaminants within aquifer sediments, which can enter the water supply. Here we find that recent groundwater pumping, observed through land subsidence, results in an increase in aquifer arsenic concentrations in the San Joaquin Valley of California. By comparison, historic groundwater pumping shows no link to current groundwater arsenic concentrations. Our results support the premise that arsenic can reside within pore water of clay strata within aquifers and is released due to overpumping. We provide a quantitative model for using subsidence as an indicator of arsenic concentrations correlated with groundwater pumping.

Overpumping leads to California groundwater arsenic threat

Nature Portfolio (Springer Nature) | June 5th, 2018

Water resources are being challenged to meet domestic, agricultural, and industrial needs. To complement finite surface water supplies that are being stressed b

Water resources are being challenged to meet domestic, agricultural, and industrial needs. To complement finite surface water supplies that are being stressed by changes in precipitation and increased demand, groundwater is increasingly being used. Sustaining groundwater use requires considering both water quantity and quality. A unique challenge for groundwater use, as compared with surface water, is the presence of naturally occurring contaminants within aquifer sediments, which can enter the water supply. Here we find that recent groundwater pumping, observed through land subsidence, results in an increase in aquifer arsenic concentrations in the San Joaquin Valley of California. By comparison, historic groundwater pumping shows no link to current groundwater arsenic concentrations. Our results support the premise that arsenic can reside within pore water of clay strata within aquifers and is released due to overpumping. We provide a quantitative model for using subsidence as an indicator of arsenic concentrations correlated with groundwater pumping.

Owens River Water Trail

Inyo County | September 1st, 2015

The Owens River Water Trail is a signature recreation project—the first dedicated water trail on a river in California. The project creates a 6.3 mile water trail on th

The Owens River Water Trail is a signature recreation project—the first dedicated water trail on a river in California. The project creates a 6.3 mile water trail on the newly re-watered Lower Owens River in the scenic Owens Valley that is solely dedicated to kayaks, canoes, and other paddlecraft. Recreationists will find well designed parking areas, accessible paths to the river, and formal paddlecraft entry and exit points.  The Owens River Water Trail is also improves aquatic habitat; opening up the river and improving transport of organic sediments. The Lower Owens River is a component of the Lower Owens River Project (LORP) which, in addition to ecosystem recovery promotes sustainable recreation. The area of the proposed water trail has a moderately wide channel characterized by large areas of open water separated by relatively short lengths of channel that are obstructed or bridged by bulrush and cattail (collectively referred to as tules). Tules and coyote willow line the margins of the open water channel; ponds open to salt grass meadow.  Tree willow is the dominate overstory. The river has a sustained 40 cfs flow and a yearly seasonal habitat flow of up to 200 cfs. The project is expected to improve water quality. Years of low flows prior to 2006 allowed tules to colonize the channel. In places, thick beds of tule roots completely cover the river bottom and vegetation blocks the channel. The seasonal habitat flows meant to move muck out the system are diminished in the vegetation and the buildup of organic material, derived from decaying tules, cannot be effectively flushed by the habitat flow. The project improves water quality by opening these blockages. The newly established channel will better fit the river’s hydrograph and is expected to improve flushing of organic sediment and protect the fishery. Inyo County and LADWP jointly manage the LORP. A preferred Recreation use plan for the LORP, which has at its core a river trail, has the support of LADWP and parties to the MOU, and was developed by a diverse range of stakeholders including the LADWP, conservation organizations, ranchers, anglers, students, area Indian Tribes, local, state, and federal agencies, local businesses, and the general public. A water trail on the Lower Owens River has popular support, and now area businesses, local agencies and NGOs are meeting to discuss forming a Lower Owens River stewardship group. The entire project area is owned by the City of Los Angeles and is open to daytime use by the public. The Owens River Water Trail is 2.5 miles from the center of Lone Pine, easily accessible by bike or car. Lone Pine aspires to be identified as a River Town; this project establishes that connection. The Lone Pine economic plan associated with the project includes a concessionaire running regularly scheduled drop-offs and pick-ups of boaters between the river and the many local hotels.

Passage of fiproles and imidacloprid from urban pest control uses through wastewater treatment plants in northern California, USA

Society of Environmental Toxicology and Chemistry (SETAC) | November 3rd, 2017

Urban pest control insecticides—specifically fipronil and its 4 major degradates (fipronil sulfone, sulfide, desulfinyl, and amide), as well as imidacloprid—were moni

Urban pest control insecticides—specifically fipronil and its 4 major degradates (fipronil sulfone, sulfide, desulfinyl, and amide), as well as imidacloprid—were monitored during drought conditions in 8 San Francisco Bay (San Francisco, CA, USA) wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13–88 ng/L), fipronil sulfone (1–28 ng/L), fipronil sulfide (1–5 ng/L), and imidacloprid (58–306 ng/L). Partitioning was also investigated; in influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter‐removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11% remaining), with partitioning into sludge (3.7–151.1 μg/kg dry wt as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical‐specific risk assessments. Environ Toxicol Chem 2017;36:1473–1482. © 2016 SETAC