Unintended consequences of water conservation on the use of treated municipal wastewater

Nature Portfolio (Springer Nature) | May 11th, 2020

Municipal water managers are intensifying efforts to reduce urban water use and increase the reliability of local water supplies to combat rising water scarcity and droug

Municipal water managers are intensifying efforts to reduce urban water use and increase the reliability of local water supplies to combat rising water scarcity and drought. Incentivizing increases in water-use efficiency and mandating conservation are two strategies to rein in demand. Concurrently, local water supplies are being augmented through investments in reclaiming and treating municipal wastewater. Although reducing urban water consumption is necessary to deal with population growth and a more variable climate, it does come at a cost. In particular, cutting back on indoor water consumption impacts the generation and quality of wastewater, which can have widespread and underappreciated consequences on human society and the environment. Here, to quantify these impacts, we tracked monthly effluent flow, salinity levels and the properties of 34 wastewater treatment plants throughout Southern California from 2013 to 2017—a period that included extreme drought and abundant precipitation. Our analysis demonstrates that conservation measures significantly reduced effluent flow and increased effluent salinity (P value ≤ 0.05). Our findings further highlight the need for policymakers to recognize the interdependencies and complexities within a water system.

Use of Set Blanks in Reporting Pesticide Results at the U.S. Geological Survey National Water Quality Laboratory, 2001–15

U.S. Geological Survey (USGS) | July 11th, 2019

Pesticide results from the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) are used for water-quality assessments by many agencies and organization

Pesticide results from the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) are used for water-quality assessments by many agencies and organizations. The USGS is committed to providing data of the highest possible quality to the consumers of its data. A cooperator’s inquiries about specific pesticide detections in water revealed potential laboratory contamination issues for some results. Consequently, the USGS conducted an extensive evaluation of potential low-level contamination related to processing or analysis of water-quality samples at NWQL for 21 pesticide compounds of interest to the cooperator. This is the most comprehensive study of NWQL pesticide quality-control (QC) results to date.

Use of the SmeltCam as an Efficient Fish-Sampling Alternative Within the San Francisco Estuary

University of California, Davis (UC Davis) | June 1st, 2021

Resource managers often rely on long-term monitoring surveys to detect trends in biological data. However, no survey gear is 100% efficient, and many sources of bias can

Resource managers often rely on long-term monitoring surveys to detect trends in biological data. However, no survey gear is 100% efficient, and many sources of bias can be responsible for detecting or not detecting biological trends. The SmeltCam is an imaging apparatus developed as a potential sampling alternative to long-term trawling gear surveys within the San Francisco Estuary, California, to reduce handling stress on sensitive species like the Delta Smelt (Hypomesus transpacificus). Although believed to be a reliable alternative to closed cod-end trawling surveys, no formal test of sampling efficiency has been implemented using the SmeltCam. We used a paired deployment of the SmeltCam and a conventional closed cod-end trawl within the Napa River and San Pablo Bay, a Bayesian binomial N-mixture model, and data simulations to determine the sampling efficiency of both deployed gear types to capture a Delta Smelt surrogate (Northern Anchovy, Engraulis mordax) and to test potential bias in our modeling framework. We found that retention efficiency—a component of detection efficiency that estimates the probability a fish is retained by the gear, conditional on gear contact—was slightly higher using the SmeltCam (mean = 0.58) than the conventional trawl (mean = 0.47, Probability SmeltCam retention efficiency > trawl retention efficiency = 94%). We also found turbidity did not affect the SmeltCam’s retention efficiency, although total fish density during an individual tow improved the trawl’s retention efficiency. Simulations also showed the binomial model was accurate when model assumptions were met. Collectively, our results suggest the SmeltCam to be a reliable alternative to sampling with conventional trawling gear, but future tests are needed to confirm whether the SmeltCam is as reliable when applied to taxa other than Northern Anchovy over a greater range of conditions.

Using a Time-of-Travel Sampling Approach to Quantify Per- and Polyfluoroalkyl Substances (PFAS) Stream Loading and Source Inputs in a Mixed-Source, Urban Catchment

American Chemical Society (ACS) | September 16th, 2024

Value of SWAMP's Statewide Monitoring Programs

California State Water Resources Control Board (SWRCB) | October 1st, 2011

One of the key features of probability-based surveys such as the Surface Water Ambient Monitoring Program’s (SWAMP) Perennial Streams Assessment (PSA) is thei

One of the key features of probability-based surveys such as the Surface Water Ambient Monitoring Program’s (SWAMP) Perennial Streams Assessment (PSA) is their lack of bias in the selection of sample sites. In the case of the PSA, each sampling location represents a known fraction of California’s stream network. This allows the State to produce statistically sound and cost-effective estimates of the condition of California’s perennial stream network.

Viability assessment for Pacific salmon and steelhead listed under the Endangered Species Act

National Marine Fisheries Service (NMFS) | July 25th, 2016

The Endangered Species Act (ESA) requires that the National Marine Fisheries Service (NMFS) review the status of listed species under its authority at least every five ye

The Endangered Species Act (ESA) requires that the National Marine Fisheries Service (NMFS) review the status of listed species under its authority at least every five years and determine whether any species should be removed from the list or have its listing status changed. Assessments of the viability of ESA-listed Pacific salmonids were conducted by the Southwest Fisheries Science Center and the Northwest Fisheries Science Center. The information from these assessments is incorporated into the West Coast Region’s status review, and the NMFS West Coast Region will make final determinations about any proposed changes in listing status, taking into account not only biological information (viability assessments) but also threats to the species and ongoing or planned protective efforts. This report from the Southwest Fisheries Science Center covers 10 ESA-listed Evolutionarily Significant Units (ESUs) and Distinct Population Segments (DPSs) that lie wholly or partially in California. In this review, we consider 1) new information relevant to the delineation of ESU/DPS boundaries, and 2) new information on status and trends in abundance, productivity, spatial structure and diversity specifically addressed by viability criteria previously developed by Technical Recovery Teams (TRTs). These viability assessments summarize current information (through the 2014–2015 spawning year where available) with respect to the viability criteria developed by the TRTs.  Consequently, the current assessments consider not only changes in populations that have occurred since the 2010 assessments but also the status of populations and ESUs/DPSs in relation to the viability criteria developed by the TRTs. For eight of the ESUs/DPSs (Southern Oregon/Northern California Coho Salmon, Central California Coast Coho Salmon, California Coastal Chinook Salmon, Northern California Steelhead, Central California Coast Steelhead, South-central California Steelhead, Southern California Steelhead, and California Central Valley Steelhead) the new information suggests that there has been no change in extinction risk since 2010 viability assessments. For two ESUs (Central Valley Spring-run Chinook Salmon, and Sacramento River Winter-run Chinook Salmon) the new information suggests a change in extinction risk. The viability of Central Valley Spring-run Chinook salmon appears to have improved since the 2010 assessment, but this ESU is far from being viable and is still facing relatively high extinction risk. The viability of Sacramento River Winter-run Chinook Salmon has been reduced and the ESU faces greater extinction risk since the 2010 assessment.

Wastewater surveillance for public health

American Association for the Advancement of Science (AAAS) | January 5th, 2023

Water and Suspended-Sediment Flux Measurements at the Golden Gate, 2016-2017

San Francisco Estuary Institute (SFEI) | December 1st, 2017

Sediment is an important resource for San Francisco Bay (SFB), in the context of restoration projects, dredging operations, ecosystem health, and contaminant transport an

Sediment is an important resource for San Francisco Bay (SFB), in the context of restoration projects, dredging operations, ecosystem health, and contaminant transport and fate. Understanding the transport and fate of sediment in SFB is important to ecosystem researchers and managers. Previous studies have shown that sediment exchange at the estuary-ocean boundary of SFB (Golden Gate inlet) is the most poorly understood element of the SFB sediment budget, owing to logistical challenges that inhibit routine field observations, and the fact that net flux is a small fraction of the instantaneous peak values experienced on a daily basis. Improved understanding of sediment exchange at the estuary-ocean boundary of SFB is essential to updating SFB-wide sediment budgets, which account for sources, sinks, and storage of sediment (and sediment-associated contaminants). In this study, field observations of water and suspended-sediment fluxes at the Golden Gate were made over one ebb tide and one flood tide on three occasions: 1) 21-22 March 2016, following a large storm event that triggered the first flow into Yolo Bypass flood control structure since 2011 2) 23 June of 2016, during a period of low freshwater inflow; 3) 27-28 February 2017, following several large storms of the wettest winter in northern California in recorded history.

Water Column Selenium Concentrations in the San Francisco Bay-Delta: Recent Data and Recommendations for Future Monitoring

San Francisco Estuary Institute (SFEI) | August 1st, 2017

The San Francisco Bay Regional Water Board developed a Total Maximum Daily Load (TMDL) and implementation plan for selenium in North San Francisco Bay (NSFB) in 2015.1 T

The San Francisco Bay Regional Water Board developed a Total Maximum Daily Load (TMDL) and implementation plan for selenium in North San Francisco Bay (NSFB) in 2015.1 The TMDL is based on attainment of water column and fish tissue target concentrations protective of human health, aquatic life, and wildlife, and was approved by the US Environmental Protection Agency in August, 2016. Analyses in support of the TMDL synthesized the results of different monitoring efforts to characterize selenium concentrations in water and biota in the Estuary. For water quality evaluation in the TMDL, the sources of observational data included studies of selenium speciation across the estuarine salinity gradient, performed in 1999-2000 and again in 2010 and 2012 (Cutter and Cutter 2004, Doblin et al. 2006, Tetra Tech, 2012), as well as samples collected by the San Francisco Bay Regional Monitoring Program (RMP). Changes in wastewater treatment from the five major refineries in NSFB were implemented in the late 1990s, leading to significant reductions in selenium loads. Data at Estuary center-line locations showed small changes for dissolved selenium in the mid-salinity range and no trends in particulate selenium (Baginska, 2015). As part of the TMDL, water quality modeling analyses were performed to characterize NSFB selenium concentrations under a range of hydrologic conditions and changing point-source loads (Baginska, 2015). Water column selenium concentration data in the NSFB and Delta continue to be collected at selected locations, although these data have not been systematically evaluated following the analyses presented in the TMDL reports. In the near term, possible changes that may cause selenium concentrations to change in the NSFB and Delta include concentration changes in the inflow from the San Joaquin River basin, changes in refinery inputs, changes in stormwater and tributary loads from the Bay margin, and changes in overall Central Valley hydrological conditions, such as the extreme wet and dry periods that occurred between 2012 and 2017. Other drivers, such as nutrient concentrations and algal levels, may also play a role, especially on the concentrations of selenium on particulates.

Water Quality Assessment of the Condition of California Coastal Waters and Wadeable Streams: Clean Water Act Section 305b Report 2006

California State Water Resources Control Board (SWRCB) | July 25th, 2006

One of the first steps in managing our environmental resources is to determine their current condition by answering the key question, “What is the overall condition of

One of the first steps in managing our environmental resources is to determine their current condition by answering the key question, “What is the overall condition of California’s surface waters?” Often-raised questions relating to the condition of our waters include, “Is the water safe to drink?” “Are the waters safe to swim?” “Are the fish safe to eat?” “Is aquatic life healthy?” The condition assessments presented in this report focus on two waterbody types: coastal bays and estuaries and wadeable perennial streams. The assessments in this report focus on the question “Is aquatic life healthy?” The “aquatic life” use designation in California’s water quality control plans refers to the beneficial uses of waters that support either warm-water or cold-water ecosystems, including fish, wildlife, invertebrates, vegetation, and other components of aquatic ecosystems. While historical assessments of water quality have primarily focused on describing chemical water quality, this report includes assessments based on biological indicators when available. This report includes assessments of the condition of coastal bays and estuaries and wadeable perennial streams statewide based on data collected through the Environmental Monitoring and Assessment Program led by the U.S. Environmental Protection Agency (U.S. EPA). These statewide assessments represent the state’s initial attempt to make broad statistical estimates of the conditions of these waterbody types. It establishes baselines against which to compare future assessments. All the statewide assessments based on Environmental Monitoring and Assessment Program datasets have known levels of certainty. These confidence intervals are not included in this report but are available in the technical reports cited. The statewide assessments rely on data from a survey design that generates statistically defensible, unbiased assessments of the conditions of these waterbody types. As such, they did not specifically focus on areas of high impact. Other sampling, which has targeted such areas have shown toxicity and elevated chemical levels in some areas. In addition, only a limited set of indicators were used for the assessments. These indicators are specified in each section. The federal Clean Water Act’s Section 305b requires each state to report on the quality condition of its waters. The California State Water Board submits its water quality condition assessment report biennially to the U.S. Environmental Protection Agency (U.S. EPA). The reports submitted by states serve as the basis for U.S. EPA’s National Water Quality Inventory Report to Congress. The Inventory Report is the primary report for the public about the condition of the nation’s waters. The report is also used to inform water quality management decisions, including the allocation of certain Clean Water Act funds among states. However, key reviews of national and state monitoring and assessment efforts suggest that the National Water Quality Inventory Report does not accurately portray water quality conditions, that the monitoring done by states does not always allow for valid assessments of water quality condition in unmonitored waters, and that a consistent approach to monitoring and data collection is needed to support core water programs (U.S. Government Accounting Office, 2000; National Research Council, 2001).  As a result, the information provided on the status and trends of waters at statewide and at national scales may be inadequate to support decision making. The water quality condition assessment reports submitted thus far by California have been based on a regional approach to reporting. The approach corresponds to the structure of the nine California Regional Water Boards and provides essential information for specific waterbodies. However, the assessments cannot be successfully integrated into an accurate statewide report because regions use a variety of assessment approaches and do not always apply criteria consistently. Also, due to limited resources, monitoring has generally focused on problem identification. Clean waters were less likely to be targeted for monitoring, and assessments were based on data with a bias towards sites that were likely sampled due to suspected problems. Furthermore, assessments could not be extrapolated to unmonitored waterbodies or those with insufficient data. That there is no current way to develop a valid national picture of water quality condition speaks both to the monitoring and assessment challenges faced by states as well as the need for improved assessment tools. The California Water Boards have actively taken steps to meet these challenges. The Surface Water Ambient Monitoring Program’s (SWAMP) comprehensive monitoring and assessment strategy describes some of these steps (A comprehensive monitoring and assessment strategy to protect and restore California’s water quality.  Surface Water Ambient Monitoring Program. 2005. [http://www.waterboards.ca.gov/swamp/reports.html]). As part of the strategy, SWAMP has partnered with U.S. EPA on large-scale monitoring efforts through the Environmental Monitoring and Assessment Program. The Environmental Monitoring and Assessment Program October 2006 Clean Water Act Section 305b Report 2006: California Water Quality Condition Assessment Report effort relies on a statistical monitoring approach that allows assessments of the condition of waters to be extrapolated to unmonitored areas. For 2006, U.S. EPA has agreed that California can use a different format to submit and meet its Clean Water Act Section 305b reporting requirements. This report would include assessments based on an evaluation of California data collected under U.S. EPA’s Environmental Monitoring and Assessment Program. The assessments apply to two waterbody types: (1) coastal bays and estuaries and (2) wadeable perennial streams. “Wadeable” streams are streams, creeks, and small rivers that are shallow enough to sample without boats. The assessments focus on one beneficial use (aquatic life use) and are based on a limited suite of key indicators. Specifically, the report had to include sections summarizing: • Statewide assessments of coastal bays and estuaries based on California data collected as part of the Environmental Monitoring and Assessment Program for Coastal Waters. • Statewide assessments of wadeable perennial streams based on aquatic invertebrate data collected in California as part of the Environmental Monitoring and Assessment Program for Inland Surface Waters. • Assessments of northern and southern coastal California’s wadeable perennial streams based on aquatic invertebrate data collected in these areas as part of the Environmental Monitoring and Assessment Program for Inland Surface Waters. When available, assessments from large-scale regional monitoring efforts such as the Regional Monitoring Program for San Francisco Bay, the Central Coast Long-Term Environmental Assessment Network, the Southern California Bight Project, and the Surface Water Ambient Monitoring Program have been included. Specifically, more detailed assessments of the San Francisco Bay, the Central Coast, and the Southern California Bight areas are included as part of the coastal waters assessment. More detailed assessments of the Santa Clara River Watershed in Southern California and waters in the Central Coast region are included as part of the wadeable perennial streams assessment. Brief summaries of the Regional Water Boards’ surface water ambient monitoring programs are included in the final section of this report.