Design and methods of the California stream quality assessment (CSQA), 2017

U.S. Geological Survey (USGS) | April 21st, 2020

During 2017, as part of the National Water-Quality Assessment Project, the U.S. Geological Survey conducted the California Stream Quality Assessment to investigate the qu

During 2017, as part of the National Water-Quality Assessment Project, the U.S. Geological Survey conducted the California Stream Quality Assessment to investigate the quality of streams in the Central California Foothills and Coastal Mountains ecoregion, United States. The goal of the California Stream Quality Assessment study was to assess the health of wadeable streams in the region by characterizing multiple water-quality factors that are stressors to aquatic biota and by evaluating the relation between these stressors and biological indicators of stream health. Urbanization, agriculture, and modifications to streamflow are anthropogenic changes that affect water quality in the region; consequently, the study design primarily targeted sites and specific stressors associated with these activities. For the study, 85 stream sites were selected to represent the types and intensity of land use in the watershed; categories of site types were undeveloped, urban (low, medium, high), agriculture (low, high), and mixed (urban and agriculture). Most sites (about 70 percent) represent a gradient of urbanization from undeveloped to 99-percent urbanized. At most of the sites, streamgages or pressure transducers were used to monitor stream discharge and stage, as well as temperature. Water-quality samples were collected routinely at all sites and were analyzed for major ions, organic contaminants, nutrients, and suspended sediment. Sampling frequency varied on the basis of site type and location. Discrete water samples were collected weekly and generally 6 times per site, except for 11 undeveloped sites that were sampled only 4 times (during the last 4 weeks). Water sampling began at sites in the southern part of the study on March 13, 2017, and at sites in the northern part of the study on April 3, 2017. Passive samplers were deployed at most sites for measurement of polar organic contaminants (pesticides and pharmaceuticals). In May 2017, coincident with completion of water-quality sampling, an ecological survey was conducted at each site to assess benthic algal and macroinvertebrate communities and instream habitat. During the ecological surveys, a single composite streambed-sediment sample was collected for chemical analysis and toxicity testing. In addition, a few focused studies were done at subsets of sites, namely, measuring pesticides using small-volume automated samplers, measuring pesticides in biofilms, and sampling suspended sediments using passive samplers. This report describes the various study components and methods of the California Stream Quality Assessment, including measurements of water quality, sediment chemistry, habitat assessments, and ecological surveys, as well as procedures for sample analysis, quality assurance and quality control, and data management.

Dioxin Issue Paper: Expert Panel Response and Recommendations

Bay Area Clean Water Agencies (BACWA) | February 11th, 2010

Congeners of dioxins and furans have been found in the San Francisco Bay in several species of fish sometimes used for human consumption, causing the State of California

Congeners of dioxins and furans have been found in the San Francisco Bay in several species of fish sometimes used for human consumption, causing the State of California to issue an interim fish consumption advisory. This fish consumption advisory has been used by the US Environmental Protection Agency and the State of California as a basis for placing the Bay on the State’s list of impaired waterways required by the Clean Water Act. As a consequence, water quality-based discharge limits for dioxins are now being placed into NPDES permits for dischargers to the Bay where dioxins or furans have been detected in effluents. At the request of the Bay Area Clean Water Agencies (BACWA), an association of municipal wastewater treatment utilities, the San Francisco Estuary Institute convened a panel of three qualified experts to review the factual case and to make recommendations. As a starting point, BACWA prepared a draft “Dioxin Issue Paper” on February 15, 2008, detailing the environmental problem, the regulatory context, and the specific  difficulties presented by dioxin-related effluent limits in permits. The draft Dioxin Issue Paper also outlined an array of possible regulatory strategies which might help resolve the difficulties faced by dischargers, ranging from strategies related to impairment listing to strategies related to NPDES permit issuance. Panel members were asked to review the draft Dioxin Issue Paper, make recommendations for improvement, and respond to a number of questions posed by the San Francisco Estuary Institute. The Panel met in Oakland, California, on February 22, 2008, at the San Francisco Estuary Institute. We were joined by representatives of the San Francisco Bay Regional Water Quality Control Board, the US Environmental Protection Agency, BACWA, and others with expertise in the field. Subsequently, we held numerous conference calls and agreed that we would address the questions posed by the Institute in both short- and long-term contexts. For the short term, we agreed upon recommendations that could help alleviate some of the dioxin-related regulatory difficulties faced by municipal wastewater treatment plants. For the long-term, however, we agreed that the problems faced by the dischargers are best addressed by solutions for the dioxin contamination problems in the Bay as a whole. We therefore also agreed to recommend a series of steps towards developing an integrated multi-media strategy for reducing dioxin levels in the San Francisco Bay.

DRERIP Ecosystem Conceptual Model: Chemical stressors

California Department of Fish and Wildlife (CDFW) | February 5th, 2008

The Sacramento-San Joaquin Delta ecosystem comprises many different habitat types, and is home to a large number of species. Thousands of chemical contaminants have been

The Sacramento-San Joaquin Delta ecosystem comprises many different habitat types, and is home to a large number of species. Thousands of chemical contaminants have been or are being introduced into the Delta. The conceptual model presented here is therefore general in nature, and is intended to provide a framework for more refined models for individual species, habitats and, in particular, contaminants of interest, for example selenium, mercury and pyrethroids. The model consists of three major submodels (Figure 1). Submodel 1: Exposure assessment which includes fate and transport of contaminants and the co-occurrence of chemicals with Delta organisms; the intermediate outcome of this submodel is “Exposure Concentration”. Submodel 2: Bioavailability of contaminants to Delta organisms; the intermediate outcome of this submodel is “Bioavailable Concentration” or “Dose”.  Submodel 3: Toxic effects assessment with the final model outcome “Population Level Effects”. In the following narrative, we provide a description for each submodel, its parameters, and linkages to other models. We discuss the model’s limitations and provide recommendations for its application in management.

DRERIP Ecosystem Conceptual Model: Mercury

California Department of Fish and Wildlife (CDFW) | January 24th, 2008

Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates

Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay-Delta, where scouring of Gold-Rush-era sediment represents an ongoing source. Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wetting-drying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated. The DRERIP mercury conceptual model and its four submodels (1. Methylation, 2. Bioaccumulation, 3. Human Health Effects, and 4. Wildlife Heath Effects) can be used to understand the general relationships among drivers and outcomes associated with mercury cycling in the Delta. Several linkages between important drivers and outcomes have been identified as important but highly uncertain (i.e. poorly understood). For example, there may be significant wildlife health effect of mercury on mammals and reptiles in the Delta, but there is currently very little or no information about it. The characteristics of such linkages are important when prioritizing and funding restoration projects and associated monitoring in the Delta and its tributaries.

DRERIP Ecosystem Conceptual Model: Pyrethroids

California Department of Fish and Wildlife (CDFW) | February 27th, 2008

To illustrate the applicability of the general model outlined in Delta Chemical Stressors conceptual model Werner et al. (2008), we are providing an example of its implem

To illustrate the applicability of the general model outlined in Delta Chemical Stressors conceptual model Werner et al. (2008), we are providing an example of its implementation for a specific group of contaminants, synthetic pyrethroid insecticides.  Although numerous different pyrethroids exist, the members of this group share many chemical and toxicological characteristics. The US EPA’s decision to phase out certain uses of organophosphate insecticides because of their potential for causing toxicity in humans has led to their gradual replacement by pyrethroids, a class of synthetic insecticides applied in both urban and agricultural areas. They are applied in urban areas primarily for structural pest control, in agricultural areas on crops such as almonds, alfalfa, cotton, lettuce, pistachios, and peaches, and in the home in pet sprays and shampoos. In 2005, five pyrethroids were among the top 21 agricultural insecticides by acres treated in California: lambdacyhalothrin (rank 7), permethrin (rank 9), esfenvalerate (rank 11), cypermethrin (rank 14) and cyfluthrin (rank 21) (California Department of Pesticide Regulation, Pesticide Use Reporting database: www.cdpr.ca.gov). Both winter storm runoff, as well as irrigation return water may be important routes of transport into aquatic systems. Pyrethroids at toxic concentrations have been detected in the majority of sediment samples collected from water bodies draining agricultural areas in the Central Valley (Weston et al., 2004; California Regional Water Quality Control Board Agricultural Waiver Program, 2007), as well as from urban creeks in the Bay/Delta region (Amweg et al., 2006; Woudneh and Oros, 2006 a, b). Pyrethroid concentrations toxic to aquatic life were detected in water samples from Central Valley agricultural drains and creeks (Central Valley Regional Water Quality Control Board, 2005; Bacey et al., 2005), and tributaries to San Francisco Bay (Woudneh and Oros, 2006 a, b). Aquatic organisms, in particular insects, crustaceans and fish, are highly sensitive to pyrethroid insecticides (Oros and Werner, 2005). Acute toxicity to fish and aquatic invertebrates is generally observed at concentrations below 1 ?g/L, and sublethal effects have been reported at low ng/L concentrations. Although it is difficult to model sublethal responses to toxicants and predict ecotoxicological impact or risk, measures of sublethal effects are likely to be as important, or more important, than the measures of acute or chronic lethal effects to accurately assess the consequences of contaminant exposure. All pyrethroids are potent neurotoxicants (Bradbury and Coats, 1989; Shafer and Meyer, 2004), can inhibit ATPases (Litchfield, 1985), and have immunosuppressive effects (Madsen et al., 1996; Clifford et al., 2005). In addition, these compounds and their breakdown products can disrupt hormone-related functions (Go et al., 1999; Tyler et al., 2000; Perry et al., 2006; Sun et al., 2007). As pyrethroid concentrations in the Delta would be expected to peak during the winter/spring storm season (Werner et al. 2004, 2006), as well as after peak agricultural application in the summer and fall (Weston et al., 2004), early life-stages of important Delta fish species or their prey may be directly exposed to these contaminants. The storm season coincides with the spawning and rearing period of several important fish such as the delta smelt, which spawns from February to June (Moyle, 1976). Juvenile fish depend on planktonic crustaceans, small insect larvae, and mysid shrimp as their major food items (Moyle 1976), which are highly sensitive to pyrethroids. It has been suggested that urban and agricultural pesticide use in the Central Valley and Delta region might play a role in the pelagic organism declines observed in the upper estuary (Oros and Werner, 2005).

Drinking water nitrate and human health: An updated review

Multidisciplinary Digital Publishing Institute (MDPI) | July 23rd, 2018

Drinking Water Notification Levels and Response Levels: An Overview

California State Water Resources Control Board (SWRCB) | February 6th, 2020

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of H

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of Health Services, CDHS, established health-based advisory levels, called “notification levels” (referred to as “action levels" through 2004), as needed since the early 1980s. These have been used to provide information to public water systems and others about certain non-regulated chemicals in drinking water that lack maximum contaminant levels (MCLs).  When chemicals are found at concentrations greater than these levels, certain requirement and recommendations apply.  Generally, notification levels have been established in response to actual contamination of drinking water supplies, e.g., perchlorate, which now has an MCL. However, notification levels for a number of chemicals were established in anticipation of possible contamination, such as from a hazardous waste site containing many pesticides (in the 1980s), or from a Superfund site (in the 2000s).  Chemicals for which notification levels are established may eventually be regulated by MCLs (through a formal regulatory process), depending on the extent of contamination, the levels observed, and the risk to human health. Most, however, have not proceeded to MCLs. Once established, a notification level generally stays in place, unless it is replaced by an MCL.On occasion, though, we have revised the numeric value of an individualnotification level to reflect new risk assessment information on the particularchemical. For some of the chemicals that had advisory levels established early on, if noMCL was adopted and the need for the notification level had passed, the advisory levelwas archived. Archived advisory levels may nevertheless be updated to reflect any newrisk information that may become available, and may be used as notification levels ifneeded. To date, of the 93 chemicals for which notification levels have been established; 40 now have MCLs. Of the remaining 53 chemicals, 29 are chemicals with current notification levels. 24 are chemicals with archived advisory levels (AALs). Note that following adoption of an MCL, the notification level is no longer used. For more about AALs and notification levels, go to: http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NotificationLevels.shtml. 

Effects of ferric sulfate and polyaluminum chloride coagulation enhanced treatment wetlands on Typha growth, soil and water chemistry

Science of the Total Environment (Elsevier) | January 15th, 2019

Land surface subsidence is a concern in many deltas worldwide as it contributes to water quality degradation, loss of fertile land and increased potential for levee f

Land surface subsidence is a concern in many deltas worldwide as it contributes to water quality degradation, loss of fertile land and increased potential for levee failure. As a possible solution to these concerns, on-site coagulation enhanced treatment wetlands (CETWs), coagulation water treatment followed by wetland passage serving as a settling basin, were implemented in a field-scale study located on a subsided island of the Sacramento-San Joaquin Delta in northern California under three treatments; coagulation with polyaluminum chloride (PAC), coagulation with ferric sulfate and an untreated control. Because CETWs offer a relatively novel solution for water quality improvement and subsidence reversal due to its low-infrastructure requirements and in-situ nature, effects from these systems remain uncharted and they may have adverse effects on plant biomass production that also contribute to sediment accretion. This study focuses on the effect CETWs had on the growth of Typha spp.; the dominant vegetation in the wetlands. Plant growth parameters and nutrient content were measured in conjunction with soil, pore water and surface water chemistry. Soil analysis indicated there was no intermixing of newly formed flocs and original soil material. Where there was significant deposition of floc, PAC treatment reduced phosphateconcentrations and ferric sulfate treatment increased total Fe concentrations in surrounding water compared to the control. Results indicated coagulation treatments had no negative effects on Typha leaf nutrient content, Typha growth or allometric parameters. Additionally, no signs of plant toxicity such as necrosis, wilting or chlorosis were observed in any of the treatments. Overall, this study suggests that CETWs are viable treatment option for water quality improvement and sediment accretion while having no negative impact on the growth of Typha plants.

Effects of vegetation on methylmercury concentrations and loads in a mercury contaminated floodplain

Science of The Total Environment (Elsevier) | August 3rd, 2023

The Yolo Bypass (YB) is a large flood conveyance system designed to protect the city of Sacramento, California, USA from flooding when the Sacramento River approaches flo

The Yolo Bypass (YB) is a large flood conveyance system designed to protect the city of Sacramento, California, USA from flooding when the Sacramento River approaches flood stage. The Sacramento River watershed and YB are a source of methylmercury (MeHg) to downstream habitat as a result of historic mercury (Hg) and gold mining practices. In the dry season, the YB is extensively farmed and grazed. However, depending on the water year, the floodplain may remain inundated for months. Our experiments focused on the role of pasture land and decomposing vegetation as a source of MeHg during extensive periods of floodplain flooding. Decomposing vegetation, rather than sediment, was identified as the principal source of filter passing MeHg (fMeHg) within the floodplain. The decomposing vegetation provided a substrate for microbial methylation of inorganic Hg contained within the plants. In replicated flooded mesocosm experiments, MeHg concentrations increased from 2.78 to 31.0 ng g− 1 dw and 3.41 to 56.8 ng g− 1 dw in decomposing vegetation. In field collections, the concentrations of MeHg in vegetation increased from preflood levels of 2.78 to 45.4 ng g− 1dw after 17 weeks of flooding. The importance of vegetation was shown in laboratory experiments where there was a positive correlation between the amount of fMeHg in water and the amount of vegetation added. These results also provide Hg concentration data for an important functional type of vegetation, grasses, and fill a data gap that contributed to uncertainties with regards to the role of vegetation in Hg cycling.

Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp

American Association for the Advancement of Science (AAAS) | July 17th, 2024