State Water Resources Control Board Research Articles

Groundwater Plume Characteristics at Small Chlorinated-Solvent Release Sites in California

There is a need to study the spatiotemporal distribution of chlorinated solvent releases in groundwater to understand the risk/threat they pose to human health, water quality, and the environment, which then can be used to prioritize clean-up and evaluate regulatory closure with appropriate risk management controls. This paper provides a statistical analysis of spatiotemporal distribution of perchloroethylene (PCE) (and its degradation products including trichloroethene [TCE]) from eighty-three cases across California for which data were available onthe State Water Resources Control Board’s GeoTracker database and the Department of Toxic Substance Control Board’s Envirostor database. These cases consisted of seventy-one dry cleaning sites and twelve other similar small solvent release sites. Statistical analyses of available groundwater data were performed to estimate: maximum concentrations at the source area, groundwater plume length, plume stability; and correlations between plume length, concentrations, and plume age. At 90% of the sites, the PCE and TCE plume lengths were less than 1,569 feet (478 meters) and 1,782 feet (543 meters), respectively. The average plume lengths for PCE and TCE were 670 feet (204 meters) and 701 feet (213 meters), respectively. At 90% of the sites that have reached stable conditions, PCE and TCE concentrations at the source areas were less than 2,670 and 660 micrograms per liter (µg/L) respectively. This study for the first time provides key characteristics of small chlorinated-solvent plume behaviors in California that can be used to prioritize management of small chlorinated-solvent release sites and to develop strategies towards achieving closure at these sites.

Distributions of waterborne pathogens in raw wastewater based on a 14-month, multi-site monitoring campaign

The California State Water Resources Control Board is the first regulatory body in the United States to develop statewide regulations for direct potable reuse (DPR). To support this effort, a pathogen monitoring campaign was undertaken to develop and implement an optimized standard operating protocol to better characterize the concentration of human pathogens in raw wastewater. Methods to detect relevant viral and protozoan pathogens in raw wastewater were optimized and implemented during a 14-month monitoring campaign. Over 120 samples were collected from five wastewater treatment plants treating a quarter of California's population. Samples were analyzed for two protozoa (Cryptosporidium and Giardia) using microscopy methods, three enteric viruses (enterovirus, adenovirus, and norovirus) using culture and/or molecular methods, and male-specific coliphage using culture methods. The method recovery efficiency was measured in every protozoa sample and every other virus sample to confirm minimum recovery efficiencies were achieved and to correct the concentrations for pathogen losses during sample processing. The results from this study provide the industry with a large, high-quality dataset as demonstrated by the high degree of method sensitivity, method recovery, and QA/QC steps. Such high-quality data on pathogen concentrations in raw wastewater are critical for confirming the level of treatment needed to reduce pathogen concentrations down to acceptable levels for potable water in DPR projects.

Removal of MS‐2 coliphage in full‐scale reverse osmosis systems

AbstractRecent activity in the potable reuse field will incorporate reverse osmosis (RO) processes that will be required to provide pathogen removal. The California State Water Resources Control Board has implemented a 12‐10‐10 log removal value (LRV) requirement for viruses, Giardia, and Cryptosporidium for groundwater recharge projects. Depending on the details of a Surface Water Source Augmentation Project, new regulations in 2018 specify an additional log reduction requirement up to a total of 14‐12‐12. Regulatory requirements that specify a treatment technique (e.g., RO) and establish log removal requirements for treatment trains are being implemented. Surrogate indicators such as electrical conductivity (EC) and total organic carbon (TOC) reduction are currently being used as online indicators to determine compliance of RO systems. The actual virus removal through a full‐scale operating system is something that has not been extensively characterized. Most of the information that exists for testing with viruses is associated with bench‐ or pilot‐scale evaluations. Evaluations of permeate from full‐scale RO systems operating with wastewater effluent as the source water indicate that viruses are not present; however, concerns remain about the potential loss of integrity through the RO system. Under the regulatory criteria established in the US Environmental Protection Agency Membrane Filtration Guidance Manual for drinking water, bulk surrogate indicators such as EC or TOC lack the sensitivity to accurately measure the actual log reduction for pathogens. It is generally recognized that the feed water quality matrix can be variable in composition, which can also affect the measurement. Bulk surrogate indicators do not satisfy the criteria for being discretely quantifiable, a term that is synonymous with the indicator having a specific molecular weight or defined composition. While alternative chemical markers such as fluorescence compounds, sulfate, or strontium yield higher LRVs, the methods are not easily implemented. An underlying issue with these indicators is that, because of their small size, they will also diffuse through the membrane and understate the pathogen removal that is occurring. An article presented in Journal AWWA proposes that the results of a conductivity profile can be used to increase the sensitivity and calculate a higher LRV. Using the dilution model as the underlying approach, the technique differentiates conductivity that would be associated with diffusion from conductivity that would be associated with a defect. Literature review of prior work with MS‐2 challenge studies has been limited to small‐scale pilot evaluations. Information regarding the removal of MS‐2 coliphage in a typical production system was not present in literature. Conceptually, there should be no difference in MS‐2 removal between a pilot‐ and a full‐scale system; however, loss of rejection due to membrane aging may be a consideration. This article provides the challenge test results of MS‐2 bacteriophage (virus) through a full‐scale RO train operating in a water recycling facility. Challenge testing was performed at various operating conditions and includes the conductivity profiling results to characterize removal under integral, as well as intentionally compromised, conditions.

Irrigation and Nitrogen Fertilizer Rate Impacts on Soil Nitrate in Potato Production

ABSTRACTParts of the Kern County have high nitrate levels in groundwater. A State Water Resources Control Board commissioned report has indicated that crop land agriculture is the main source of nitrates in the groundwater. Annual rainfall is less than 20 cm, thus irrigation is necessary for optimum crop production. A project was undertaken to evaluate current nitrogen fertility and irrigation scheduling in potato production and their contribution, or lack thereof, to nitrate movement in the soil profile and potential nitrate contamination of groundwater. A line-source sprinkler plot area was established to create soil moisture regimes of 120% of target, target (optimum soil moisture for potato growth) and 80% of target. Pre-plant and post-harvest soil samples were collected to a depth of 2 meters. Plant, root and tuber samples were collected and analyzed for nitrogen content. Soil moisture and irrigation amounts were monitored. Plant dry matter and tuber yield increased with each N rate increase. The high N rate increased plant growth disproportionally to the increased tuber yield. Appropriate irrigation scheduling did not produce water movement beyond the effective potato rooting zone. Excessive irrigation moved soil nitrate deeper into the soil profile.

Assessment of the contribution of utility vault water to surface water pollution

Utility vaults and underground structures house essential telecommunications, gas, and electrical infrastructure (e.g., transformers, copper wiring) that could contaminate water which accumulates in them. Water is removed from utility vaults during routine infrastructure maintenance. That water is typically released to the storm drain system, raising concerns that polluted water could reach receiving waters. However, no one has measured pollutants in utility vault water. The State Water Resources Control Board (SWRCB) has mandated such measurements as a condition of renewing the National Pollutant Discharge Elimination System Utility Vault Permit. We analyzed 126 priority pollutants in 20 utility vault water samples collected throughout California by Pacific Gas and Electric Company (PG&E). We also estimated the volume of utility vault water discharged and calculated loads. Twenty-one priority pollutants were detected. Metals were commonly found. Only copper (Cu) and zinc (Zn) exceeded water quality criteria. Their maximum concentrations were 791 and 386 μg/L, respectively. Median Cu and Zn concentrations of 9.66 and 81.6 μg/L were representative of urban stormwater, suggesting runoff is a source of metals in utility vault water. For San Francisco Bay, Cu and Zn loads from PG&E's utility vault water (0.06 and 0.5 kg/year) were inconsequential compared to previously reported total loads (74,000 and 320,000 kg/year) from stormwater, wastewater treatment plants, etc. For California, utility vault water loads were 5 and 40 kg/year of Cu and Zn. We are the first to report pollutant concentrations in utility vault water. Utility vaults are not a major source of pollutants to receiving waters.

Factors affecting 1,2,3-trichloropropane contamination in groundwater in California

1,2,3-Trichloropropane (1,2,3-TCP) is a volatile organic chemical of eminent concern due to its carcinogenic, mutagenic, and reproductive effects, and its frequent occurrence at concentrations of concern worldwide. In California, 1,2,3-TCP was detected in 6.5% of 1237 wells sampled by the U. S. Geological Survey (USGS). About 8% of domestic wells had a detection of 1,2,3-TCP, compared to 5% of public-supply wells. 1,2,3-TCP was detected in 5.5% of most recent samples from 7787 public-supply well sources of the California State Water Resources Control Board Division of Drinking Water (DDW). Concentrations ranged from <0.005 to 2.7 μg/L. The California maximum contaminant level (MCL) is 0.005 μg/L. Most of the detections occurred in the San Joaquin Valley, where 1,2,3-TCP was detected above the MCL in 16% of USGS sampled wells and 18% of DDW wells. 1,2,3-TCP occurrence and concentrations are related to legacy fumigant use and hydrogeologic factors. Understanding factors affecting 1,2,3-TCP will aid in determining vulnerability and long term persistence in the San Joaquin Valley, which can help focus efforts to manage drinking water resources on the most vulnerable areas and also inform efforts in other areas of the state and worldwide. Widespread occurrence of 1,2,3-TCP is related to nonpoint source agricultural contaminant inputs. High concentrations of 1,2,3-TCP are in young, shallow, oxic groundwater beneath primarily orchard/vineyard crops. These areas are in coarse-grained sediments that promote rapid recharge, related to proximal alluvial fan sediments deposited by large streams that drain glaciated watersheds of the Sierra Nevada. 1,2,3-TCP co-occurs with 1,2-dibromo-3-chloropropane (DBCP) and 1,2-dichloropropane (1,2-DCP) throughout modern age groundwater, indicating its long term persistence with little degradation. The highest concentrations of 1,2,3-TCP were observed at point source cleanup sites in urban areas; depending on the age and source of groundwater to nearby public-supply wells, these areas may see increasing concentrations of 1,2,3-TCP.

Purifying Water: Responding to Public Opposition to the Implementation of Direct Potable Reuse in California

Direct Potable Reuse (DPR) is a method of recycling wastewater to create a potable water source. DPR is a particularly useful technology in arid, drought-prone regions, including California, because it is a self-sustaining water source. Despite being safe, efficient, and useful, potable reuse methods, including DPR, have faced intense public opposition. Such opposition has stopped several projects in California.In January 2018, California State Assembly Bill 574 (AB 574) took effect. AB 574 requires California’s State Water Resources Control Board to adopt regulations for DPR by 2023, so long as the regulations are found to adequately protect public health. Once adopted, California would become the first state to have uniform regulations for DPR. But while uniform regulations will be an important step toward the realization of DPR technology, California’s success in implementing DPR will ultimately depend on public acceptance of DPR as a legitimate source of water.This Comment seeks to provide California’s state and local governments with strategies to garner public support for DPR projects. First, this Comment provides a framework for gaining public acceptance of DPR. Second, this Comment explains why California is well-suited to the adoption of DPR technology, and describes California’s history with potable reuse. Third, this Comment illustrates the main obstacle to DPR—public opposition—through a series of case studies. Fourth and finally, this Comment applies the framework for gaining public acceptance to the case studies to illustrate a holistic approach to legitimizing DPR. “When was sewage ever classified as being pure?” asked the Revolting Grandmas, a San Diego grassroots group.[1] The Grandmas were revolting against recycling wastewater for potable use, also known as ‘potable reuse.’ They feared waterborne illness, distrusted the purification technology, and were simply disgusted by the idea of drinking water that once went down someone’s toilet.[2] And they were not alone in their concerns. Public opposition to recycled wastewater has stopped several potable reuse projects in California. Public concerns about recycled wastewater derive, in part, from an ancient human fear of waterborne disease that has complicated mankind’s relationship with water: “[t]here is no life without water. Indeed, we use its presence as an indicator for the possibility of life beyond the earth. But drinking water can kill, and always has.”[3] [1]. See Cal. Dep’t of Water Res., Water Recycling 2030: Recommendations of California’s Recycled Water Task Force app. at G-52 (2003), https://water.ca.gov/LegacyFiles/pubs/use/water_recycling_2030/recycled_water_tf_report_2003.pdf [https://perma.cc/9MQ2-Y54H]. [2]. Seeid. app. at G-58. [3]. James Salzman, Drinking Water: A History 21 (2012).

The estimated impact of California’s urban water conservation mandate on electricity consumption and greenhouse gas emissions

In April 2015, the Governor of California mandated a 25% statewide reduction in water consumption (relative to 2013 levels) by urban water suppliers. The more than 400 public water agencies affected by the regulation were also required to report monthly progress towards the conservation goal to the State Water Resources Control Board. This paper uses the reported data to assess how the water utilities have responded to this mandate and to estimate the electricity savings and greenhouse gas (GHG) emissions reductions associated with reduced operation of urban water infrastructure systems. The results show that California succeeded in saving 524 000 million gallons (MG) of water (a 24.5% decrease relative to the 2013 baseline) over the mandate period, which translates into 1830 GWh total electricity savings, and a GHG emissions reduction of 521 000 metric tonnes of carbon dioxide equivalents (MT CO2e). For comparison, the total electricity savings linked to water conservation are approximately 11% greater than the savings achieved by the investor-owned electricity utilities’ efficiency programs for roughly the same time period, and the GHG savings represent the equivalent of taking about 111 000 cars off the road for a year. These indirect, large-scale electricity and GHG savings were achieved at costs that were competitive with existing programs that target electricity and GHG savings directly and independently. Finally, given the breadth of the results produced, we built a companion website, called ‘H2Open’ (https://cwee.shinyapps.io/greengov/), to this research effort that allows users to view and explore the data and results across scales, from individual water utilities to the statewide summary.

Changing patterns in water toxicity associated with current use pesticides in three California agriculture regions.

Regulation of agriculture irrigation water discharges in California, USA, is assessed and controlled by its 9 Regional Water Quality Control Boards under the jurisdiction of the California State Water Resources Control Board. Each Regional Water Board has developed programs to control pesticides in runoff as part of the waste discharge requirements implemented through each region's Irrigated Lands Regulatory Program. The present study assessed how pesticide use patterns differ in the Imperial (Imperial County) and the Salinas and Santa Maria (Monterey County) valleys, which host 3 of California's prime agriculture areas. Surface-water toxicity associated with current use pesticides was monitored at several sites in these areas in 2014 and 2015, and results were linked to changes in pesticide use patterns in these areas. Pesticide use patterns appeared to coincide with differences in the way agriculture programs were implemented by the 2 respective Regional Water Quality Control Boards, and these programs differed in the 2 Water Board Regions. Different pesticide use patterns affected the occurrence of pesticides in agriculture runoff, and this influenced toxicity test results. Greater detection frequency and higher concentrations of the organophosphate pesticide chlorpyrifos were detected in agriculture runoff in Imperial County compared to Monterey County, likely due to more rigorous monitoring requirements for growers using this pesticide in Monterey County. Monterey County agriculture runoff contained toxic concentrations of pyrethroid and neonicotinoid pesticides, which impacted amphipods (Hyalella azteca) and midge larvae (Chironomus dilutus) in toxicity tests. Study results illustrate how monitoring strategies need to evolve as regulatory actions affect change in pesticide use and demonstrate the importance of using toxicity test indicator species appropriate for the suite of contaminants in runoff in order to accurately assess environmental risk. Integr Environ Assess Manag 2018;14:270-281. © 2017 SETAC.

The Welfare Consequences of the 2015 California Drought Mandate: Evidence from New Results on Monthly Water Demand

In response to the severe California drought, in April 2015, Governor Jerry Brown issued an executive order mandating statewide reductions in water use. The mandate aimed to reduce the amount of water consumed statewide in urban areas by 25% from 2013 levels. The State Water Resources Control Board (SWRCB) proposed regulatory instructions that grouped urban water utilities into nine tiers, with conservation standards ranging from 8% to 36%. In this paper we evaluate welfare losses caused by this mandate. Understanding the proposed regulation’s welfare losses requires estimating water demand. Using fixed effect models and data from 2004 to 2009 on 111 urban water utilities, an annual demand curve is estimated. The estimated demand elasticity is between -0.61 and -0.1 which is heterogeneous across the regions and seasons. In the second step, we use the estimated annual demand function to recover price elasticities for a sample of 53 urban water utilities in California, which provide water for more than 20 million customers. We considered two scenarios to calculate welfare losses in Northern and Southern California: the governor’s mandate, and a hypothetical 25% uniform cut back. The results for Northern California indicate an average welfare loss of $6,132 per acre-foot of shortage for a governor’s mandate and $4,424 for a 25% uniform shortage. In Southern California, the average estimated welfare loss is $2,113 per acre-foot of shortage for a governor’s mandate and $2,171 for a 25% uniform shortage. Results indicate the monthly household-level willingness-to-pay to avoid the governor’s mandate is $36 in Northern California and $25 in Southern California. Our results suggest inefficiencies in the distribution of the percentage cutbacks between Northern California utilities from SWRCB.

Triennial changes in groundwater quality in aquifers used for public supply in California: utility as indicators of temporal trends.

From 2004 to 2011, the U.S. Geological Survey collected samples from 1686 wells across the State of California as part of the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). From 2007 to 2013, 224 of these wells were resampled to assess temporal trends in water quality. The samples were analyzed for 216 water-quality constituents, including inorganic and organic compounds as well as isotopic tracers. The resampled wells were grouped into five hydrogeologic zones. A nonparametric hypothesis test was used to test the differences between initial sampling and resampling results to evaluate possible step trends in water-quality, statewide, and within each hydrogeologic zone. The hypothesis tests were performed on the 79 constituents that were detected in more than 5% of the samples collected during either sampling period in at least one hydrogeologic zone. Step trends were detected for 17 constituents. Increasing trends were detected for alkalinity, aluminum, beryllium, boron, lithium, orthophosphate, perchlorate, sodium, and specific conductance. Decreasing trends were detected for atrazine, cobalt, dissolved oxygen, lead, nickel, pH, simazine, and tritium. Tritium was expected to decrease due to decreasing values in precipitation, and the detection of decreases indicates that the method is capable of resolving temporal trends.

Unanswered questions for implementation of the Sustainable Groundwater Management Act

Outlook Unanswered questions for implementation of the Sustainable Groundwater Management Act Michael Kiparsky, Director, Wheeler Water Institute, Center for Law, Energy & the Environment, UC Berkeley School of Law A rig drills a new well in Merced County. In the foreground is a pressure relief structure for subsurface water pipes. Groundwater accounts for between one-third and two-thirds of California’s water use in a given year and serves as a lifeline when surface water runs low during drought. In part because of California’s historical lack of groundwater use regulation, this crucial resource is threatened. In some areas, declining groundwater levels have caused the land surface to subside at a rate of more than one inch per month, damaging roads, canals and pipelines. Falling water tables are driving a well-drilling race that threatens farms, communi- ties and ecosystems. To address the problem of chronic groundwa- ter overdraft, SGMA, adopted in 2014, declares a state policy of managing groundwater sustainably, with sustainability defined as avoiding six specific undesirable results. These are “significant and unreasonable” (1) lowering of groundwater levels, (2) reduction in groundwater storage, (3) seawater intrusion, (4) water quality degradation, (5) land subsidence and (6) impacts on beneficial uses of interconnected surface waters. In concept, this forward-thinking framing aligns the requirements of the law with the im- pacts of unsustainable groundwater use and the actions needed to address those impacts. To accomplish these objectives, SGMA relies primarily on local control, with an enforcement backstop provided by the State Water Resources Control Board. New local entities called groundwa- ter sustainability agencies (GSAs) will do the bulk of the work of implementing SGMA by developing, implementing and updating groundwater sustain- ability plans (GSPs). A GSP provides the template for achieving sustainable groundwater manage- ment in a GSA’s jurisdiction within 20 years. GSAs must be formed by 2017 and GSPs completed by 2020 or 2022. http://calag.ucanr.edu • OCTOBER–DECEMBER 2016 165 Leigh Bernacchi C alifornia is grappling with the implications of the Sustainable Groundwater Management Act (SGMA), a visionary and potentially revolutionary law that could profoundly change the way water is managed in the state. The nature of the revolution, however, is not yet clear. Whether and how SGMA achieves its goals hinges on open questions about its implementation.

What Are Some Effective Ways to Manage Stormwater?

Recent legislation in California and increased awareness of stormwater‐related environmental issues have led to continued changes and innovative approaches to stormwater management and regulation that could be applied in many states. In 2016, the California State Water Resources Control Board (State Water Board) adopted its Storm Water Strategy (http://bit.ly/2a5GD5A) to further develop innovative regulatory and management approaches to maximize uses of stormwater as a resource.

Development of a Water Quality Model to Support a Pathogen TMDL (Newport Bay, California, USA)

Newport Bay (Orange County, California) is listed by the California State Water Resources Control Board (SWRCB) as a water quality limited receiving water body because of sporadic exceedances of the fecal coliform water quality objectives for body contact recreation. Consistent with federal and state requirements, a Total Maximum Daily Load (TMDL) is being implemented in the watershed. The fecal coliform TMDL in Newport Bay is a phased approach for understanding and controlling the microbiological water quality in the to ensure the reasonable protection of the Bay's beneficial uses. An important initial step within that TMDL was to assess the impairment of the body contact recreation beneficial use (REC-1) of Newport Bay receiving waters through characterizing the risk of illness associated with REC-1 exposure. A health risk assessment investigation was developed to characterize that risk. The health risk assessment investigation involved the integration of a population based model of disease transmission, a water quality modeling component necessary for estimating pathogen dose as part of the exposure assessment, and site-specific population use and receiving water data collection. The Water Environment Research Foundation funded the water quality modeling component of the health risk assessment investigation, which is the focus of this report. Also provided within this report is an overview of the health risk assessment methodology, a summary of the major findings from the risk assessment investigation, and a discussion of how the health risk methodology may be applied to other watersheds where impairment of the REC-1 beneficial use is in question. The major findings of the health risk assessment investigation indicated that (1) the risk of illness from REC-1 use in Newport Bay, estimated using two separate methods was generally below levels considered tolerable by US EPA, and (2) the reduction of controllable sources of pollution would not appreciably reduce the existing risk. Based on the collection of site-specific exposure data and the health risk characterization, it was determined that evaluating the impairment of the REC-1 beneficial use requires a more rigorous and comprehensive health based approach than that prescribed by the current regulations for recreational waters. This title belongs to WERF Research Report Series ISBN: 9781843396642 (Print) ISBN: 9781780403137 (eBook)

United States v. State Water Resources Control Board: A Comprehensive Approach to Water Policy in California

United States v. State Water Resources Control Board: A Comprehensive Approach to Water Policy in California

“The arsenic threat: interdependencies of water, agriculture, food supply, public health and energy critical infrastructure”

On February 7, 2013, the Associated Press reported [1] that “more than half of California’s population relies on a drinking water supply contaminated by arsenic, nitrates and other contaminants, though most communities blend or treat their water to make it safe, according to a new report by the State Water Resources Control Board released earlier this week. . . Arsenic was the most-detected naturally occurring contaminant, while nitrate was the human-caused contaminant detected the most. Chemical fertilizers and livestock manure are the main source of nitrate contamination in groundwater. . . Some communities cannot afford water treatment or other alternatives.” The report further stated 265 community water systems have delivered water from wells that have exceeded the nitrate, arsenic, or other standards. Most of these communities are located in rural Kern, Tulare, and Madera counties and serve contaminated water to about 2 million Californians [1]. The access and the quality of our drinking water is and should be a major concern to guarantee the global citizen’s safety and security regardless where people live. The original intention of this paper was to further investigate and better understand the risks and the consequences of the February 2013 water report from the State of California where the drinking water in many locations was found to have high levels of arsenic. In the literature, we found many products in the food chain that contain arsenic, and that led us to look deeper into the nexus between water, agriculture, food (i.e., cattle, poultry, fish/aquaculture, etc.) and even the energy sector, because of the current practices of fracking and the derived concerns of contamination to our environment, the water, the soil, and all the derived products. We realized very quickly that this is not a California issue but rather a Global Health one.

100 years of California’s water rights system: patterns, trends and uncertainty

For 100 years, California’s State Water Resources Control Board and its predecessors have been responsible for allocating available water supplies to beneficial uses, but inaccurate and incomplete accounting of water rights has made the state ill-equipped to satisfy growing societal demands for water supply reliability and healthy ecosystems. Here, we present the first comprehensive evaluation of appropriative water rights to identify where, and to what extent, water has been dedicated to human uses relative to natural supplies. The results show that water right allocations total 400 billion cubic meters, approximately five times the state’s mean annual runoff. In the state’s major river basins, water rights account for up to 1000% of natural surface water supplies, with the greatest degree of appropriation observed in tributaries to the Sacramento and San Joaquin Rivers and in coastal streams in southern California. Comparisons with water supplies and estimates of actual use indicate substantial uncertainty in how water rights are exercised. In arid regions such as California, over-allocation of surface water coupled with trends of decreasing supply suggest that new water demands will be met by re-allocation from existing uses. Without improvements to the water rights system, growing human and environmental demands portend an intensification of regional water scarcity and social conflict. California’s legal framework for managing its water resources is largely compatible with needed reforms, but additional public investment is required to enhance the capacity of the state’s water management institutions to effectively track and regulate water rights.

Monitoring the aquatic toxicity of mosquito vector control spray pesticides to freshwater receiving waters

Pesticides are applied to state and local waterways in California to control insects such as mosquitoes, which are known to serve as a vector for West Nile Virus infection of humans. The California State Water Resources Control Board adopted a National Pollutant Discharge Elimination System General Permit to address the discharge to waters of the United States of pesticides resulting from adult and larval mosquito control. Because pesticides used in spray activities have the potential to cause toxicity to nontarget organisms in receiving waters, the current study was designed to determine whether toxicity testing provides additional, useful environmental risk information beyond chemical analysis in monitoring spray pesticide applications. Monitoring included a combination of aquatic toxicity tests and chemical analyses of receiving waters from agricultural, urban, and wetland habitats. The active ingredients monitored included the organophosphate pesticides malathion and naled, the pyrethroid pesticides etofenprox, permethrin, and sumithrin, pyrethrins, and piperonyl butoxide (PBO). Approximately 15% of the postapplication water samples were significantly toxic. Toxicity of half of these samples was attributed to the naled breakdown product dichlorvos. Toxicity of 2 other water samples likely occurred when PBO synergized the effects of pyrethroid pesticides that were likely present in the receiving system. Four of 43 postapplication sediment samples were significantly more toxic than their corresponding pre-application samples, but none of the observed toxicity was attributed to the application events. These results indicate that many of the spray pesticides used for adult mosquito control do not pose significant acute toxicity risk to invertebrates in receiving systems. In the case of naled in water, analysis of only the active ingredient underestimated potential impacts to the receiving system, because toxicity was attributed to the breakdown product, dichlorvos. Toxicity testing can provide useful risk information about unidentified, unmeasured toxicants or mixtures of toxicants. In this case, toxicity testing provided information that could lead to the inclusion of dichlorvos monitoring as a permit requirement.

The list of lists – are we measuring the best PPCPs for detecting wastewater impact on a receiving water?

Determining an appropriate set of indicators to show that a water supply is not impacted by wastewater is critical for watershed protection and for potable reuse projects. In 2010 the California State Water Resources Control Board (CA SWRCB) Blue Ribbon Panel issued a set of recommendations for a very short list (7) of compounds to be monitored for re-use projects. In 2009/10 the Santa Ana Watershed Project Authority (SAWPA) developed a separate list of potential wastewater indicator compounds (11) based on a consensus panel, with the intention of sampling all dischargers to the Santa Ana River to determine occurrence. In 2009, the Water Research Foundation (WaterRF) funded project 4167, which examined analytical performance for 22 potential compounds of interest for assessing drinking water. In 2010, a NWRI report suggested primidone as a tracer. In 2009 Buerge et al. demonstrated the effectiveness of artificial sweeteners as conservative wastewater tracers. There is some overlap among these lists but there are also some potential key indicators that are only on a single proposed list and the potential that some are on ‘none’ of the lists. MWH developed a direct online extraction/analysis method using LC-MS-MS for nearly 90 target analytes that covers all of the compounds listed in the projects above. This method has reporting limits for most of the analytes in the 5–10 ng/L range. In 2010 and again in 2011, this technique was used for a SAWPA effluent monitoring project to assess the relative amount of information obtained from the different lists. Samples from 17 wastewater effluents and the downstream receiving water were tested for ∼90 analytes. We compared (a) frequency of detection in the effluent samples (b) concentration range and (c) variability among dischargers. Data were compared to other locations collected across the country and to municipal drinking water sources and distribution system samples to determine the most persistent compounds (and therefore best indicators). The ideal generic tracer should be relatively abundant and show minimal concentration variation. It is apparent that none of the existing lists (SAWPA, SWRCB, WaterRF, primidone, sucralose/acesulfame-K) is a ‘perfect’ list and greater discerning power is obtained by looking at long lists. Specifically the SAWPA list suffers because only one compound, TCEP was detected in all effluent samples, and concentration varied by a factor of 10 among dischargers. The CA SWRCB list suffers because only sucralose was detected in all samples; iopromide was only detected in about 50% of the samples and gemfibrozil in an even smaller number of effluents. Primidone, while occurring in 100% of samples varies by five fold among local sources and thus may not be the ideal tracer. Many of the compounds in the WaterRF list are not even among the most commonly detected analytes in effluents. Taking advantage of the power of a long list covering various classes of compounds it becomes possible to identify both generic (sucralose, acesulfame-K, TCEP, primidone) and specific (iohexal, atenolol, butalbital, caffeine degradates such as theobromine and 1, 7-dimethylxanthine, triazine and degradates) tracers to not only determine the presence of wastewater, but also potential specific primary wastewater sources. Several of the compounds seen most frequently that also have less than ten fold variation include ones not commonly measured (Dehydronifedipine, dilantin, meprobamate). Once the appropriate target analytes are identified for a given set of dischargers, future monitoring can then use a smaller set, but a-priori determination of a short list of indicators may eliminate significant important potential tracer compounds.

Transitioning sediment quality assessment into regulations: Challenges and solutions in implementing California's sediment quality objectives

Development and promulgation of sediment quality criteria represents a substantial challenge for water quality agencies. Unlike water quality programs that rely on individual chemical thresholds to assess water quality, the complex processes affecting contaminant bioavailability in sediments preclude the use of contaminant concentrations to independently assess impacts or identify cause. Various multiple line of evidence approaches (e.g., sediment quality triad) have been developed for sediment quality assessment, but such frameworks are rarely fully incorporated into statewide regulatory programs due to a lack of standardized and validated tools. In 2003, California's State Water Resources Control Board (State Water Board) initiated development of sediment quality criteria and an assessment framework that required the developers to resolve many challenging technical and policy related issues to the satisfaction of stakeholders, scientists, and the general public. The first part of this multiyear effort has been completed and resulted in the development and validation of an integrated collection of tools, thresholds, and a data interpretation framework for assessing sediment contamination impacts on benthic community condition. The State Water Board's narrative sediment quality criteria and assessment framework became effective in 2009, following US Environmental Protection Agency approval. The results of this effort are described in a series of 6 articles published in this issue of Integrated Environmental Assessment and Management. The articles describe: 1) a multiple line of evidence framework for data integration and assessment, 2) calibration and evaluation of sediment quality guidelines for predicting toxic responses, 3) development and evaluation of sediment quality guidelines with respect to benthic macrofauna responses, 4) selection of toxicity test methods and thresholds, 5) identification and characterization of benthic community assemblages, 6) the effect of sampling methods on benthic community assessment, and 7) recommendations on improving the assessment of contaminant exposure in sediment quality assessment. This collection of articles illustrates the steps needed to improve the scientific foundation for sediment quality assessment in regulatory applications.