8

Ecological Enhancement via Water Reuse

Rivers, lakes, and streams provide many recreational activities and benefits, as well as important ecosystem services such as nutrient cycling, wildlife habitat, and flood mitigation. With the increasing demand in urban and agricultural areas for freshwater, few options are available to ensure that aquatic systems maintain their respective ecohydrological requirements (Neubauer et al., 2008). Environmental applications of water reuse include river and wetland habitat creation and augmentation of existing water sources for the express purpose of improving conditions for aquatic biota. The Florida Everglades, for example, are at risk due to a decrease of incoming freshwater (see Box 8-1). For areas such as the Everglades and others, water reuse for ecological enhancement may be a beneficial option because reclaimed water could be used to augment streamflow, restore wetlands, and/or enhance water quality (Wintgens et al., 2008; Carey and Migliaccio, 2009). In addition to ecological benefits, there may also be economic benefits (e.g., increased tourism, hurricane protection) from such projects (Carvalho, 2007; Costanza et al., 2008; see also Chapter 9).

Reclaimed water may have potential for augmenting existing surface water systems and creating new habitats. In most instances, reclaimed water used for the purpose of ecological enhancement will meet or exceed local wastewater discharge standards. Nevertheless, the ecological risk of such planned applications needs to be considered to ensure that the level of risk to the environment is acceptable relative to the benefits. The level of acceptable ecological risk in these projects will likely vary between reuse scenarios; for example, the acceptable level of risk in a newly constructed wetland may be different than in a pristine system such as the Everglades. The level and cost of the assessment will also vary depending on the scenario.

Based on these considerations, the purpose of this chapter is to (1) present what is known about risks associated with the purposeful reuse of treated wastewater for habitat restoration and creation, (2) describe methods for assessing ecological risks from a historical and state-of-the-science perspective, and (3) recommend future research needs in the area of water reuse and ecological risk assessment.

POTENTIAL CONCERNS ABOUT ENVIRONMENTAL APPLICATIONS

As presented in Chapter 2, treated wastewater is routinely discharged to the nation’s rivers as part of the wastewater disposal process, with nearly 99 percent of wastewater discharges receiving secondary or greater treatment (see Table 2-1). The quality of reclaimed water used for ecological applications would be no lower than that of traditional wastewater discharge, and may be treated to higher levels. Therefore, available data on the ecological effects from the chemical, physical, and biological stressors in treated wastewater effluent discharged to rivers and lakes provide a worst case scenario of effects that could occur in ecological enhancement water reuse projects.

Typical wastewater discharges contain a mixture of microbes, inorganic chemicals, and organic chemicals, some of which may cause adverse ecological effects in



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8 Ecological Enhancement via Water Reuse Rivers, lakes, and streams provide many recre- the acceptable level of risk in a newly constructed wet- ational activities and benefits, as well as important land may be different than in a pristine system such as ecosystem services such as nutrient cycling, wildlife the Everglades. The level and cost of the assessment habitat, and flood mitigation. With the increasing will also vary depending on the scenario. demand in urban and agricultural areas for freshwater, Based on these considerations, the purpose of this few options are available to ensure that aquatic systems chapter is to (1) present what is known about risks maintain their respective ecohydrological requirements associated with the purposeful reuse of treated waste- (Neubauer et al., 2008). Environmental applications of water for habitat restoration and creation, (2) describe water reuse include river and wetland habitat creation methods for assessing ecological risks from a historical and augmentation of existing water sources for the and state-of-the-science perspective, and (3) recom- express purpose of improving conditions for aquatic mend future research needs in the area of water reuse biota. The Florida Everglades, for example, are at risk and ecological risk assessment. due to a decrease of incoming freshwater (see Box 8-1). For areas such as the Everglades and others, water reuse POTENTIAL CONCERNS ABOUT for ecological enhancement may be a beneficial option ENVIRONMENTAL APPLICATIONS because reclaimed water could be used to augment streamflow, restore wetlands, and/or enhance water As presented in Chapter 2, treated wastewater is quality (Wintgens et al., 2008; Carey and Migliaccio, routinely discharged to the nation’s rivers as part of the 2009). In addition to ecological benefits, there may wastewater disposal process, with nearly 99 percent of also be economic benefits (e.g., increased tourism, hur- wastewater discharges receiving secondary or greater ricane protection) from such projects (Carvalho, 2007; treatment (see Table 2-1). The quality of reclaimed Costanza et al., 2008; see also Chapter 9). water used for ecological applications would be no Reclaimed water may have potential for augment- lower than that of traditional wastewater discharge, ing existing surface water systems and creating new and may be treated to higher levels. Therefore, avail- habitats. In most instances, reclaimed water used for able data on the ecological effects from the chemical, the purpose of ecological enhancement will meet or physical, and biological stressors in treated wastewater exceed local wastewater discharge standards. Neverthe- effluent discharged to rivers and lakes provide a worst- less, the ecological risk of such planned applications case scenario of effects that could occur in ecological needs to be considered to ensure that the level of risk enhancement water reuse projects. to the environment is acceptable relative to the benefits. Typical wastewater discharges contain a mixture of The level of acceptable ecological risk in these projects microbes, inorganic chemicals, and organic chemicals, will likely vary between reuse scenarios; for example, some of which may cause adverse ecological effects in 133

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134 WATER REUSE For instance, chlorine is often used as a disinfection BOX 8-1 chemical to reduce pathogen load and disease risk in Proposed Reuse Projects to Expand wastewater. Low levels of chlorine may cause toxicity Environmental Water Supply in the in the receiving stream or form chlorinated byproducts Everglades capable of causing ecotoxicity. Organic chemicals in wastewater have the potential to deplete the receiving The Comprehensive Everglades Restoration Plan (CERP) aquatic system of oxygen, thus impacting aquatic life. was envisioned as a multidecadal effort to achieve ecological Suspended solids from wastewater can block sunlight, restoration by reestablishing the hydrological characteristics of the historic Everglades ecosystem, where feasible, and to thus reducing the photosynthetic capability of aquatic create a water system that simultaneously serves the needs plants. Reduction in sunlight penetration may reduce of both the natural and human systems of South Florida plant life, as well as vertebrate and invertebrate popula- (NRC, 2010). The conceptual plan (USACE/SFWMD, 1999) tions. All of these stressors singularly or in combination included 68 different project components focused on restor- may affect aquatic life, which includes macroinver- ing the quantity, quality, timing, and distribution of water in tebrates, fish, plants, and amphibians (Sowers et al., the ecosystem. The largest component of the budget for this $13 billion project is devoted to water storage, including 2009; Brix et al., 2010; Slye et al., 2011). Ecological conventional surface water storage reservoirs, in-ground assessments of wastewater effluent-dominated surface reservoirs, aquifer storage and recovery, and seepage manage- waters have shown that aquatic life can be sustained in ment. To provide sufficient water supply to meet anticipated these types of waters; however, site-specific factors may future environmental, urban, and agricultural water demands influence the aquatic life in various locations (Brooks in South Florida, the comprehensive plan included two water et al., 2006; Slye et al., 2011). reuse projects in Miami-Dade County, which together would treat more than 200 million gallons per day (MGD; 760 mil- Many studies associated with municipal effluents lion m3/d). In the preliminary project concept, the reclaimed have been focused on standard measures of water water would be used for aquifer recharge to enhance urban quality, such as pH, temperature, total nitrogen and water supplies and reduce seepage out of the Everglades. phosphorus, dissolved oxygen, and the impact of the Additionally, reclaimed water could be provided to Biscayne effluent on the receiving system (Howard et al., 2004; Bay National Park to help meet freshwater flows to support Kumar and Reddy, 2009; Odjadjare and Okoh, 2010). ecosystem needs. However, the plan acknowledged the high costs of such treatment to support ecological needs and noted Regulatory agencies, such as the U.S. Environmental that other potential sources of water would be investigated Protection Agency (EPA), have developed guidance before water reuse was pursued. documents and criteria for many of these water quality Pilot projects were planned to assess the “cost effective- parameters on a site-specific or ecoregion basis. Further, ness and environmental feasibility of applying reclaimed the EPA created the National Pollutant Discharge water to sensitive natural areas” and to “identify treatment Elimination System to prevent aquatic life impacts as- targets consistent with preventing degradation to natural area,” among other objectives. A pilot plant was constructed by sociated with these traditional forms of wastewater pol- Miami-Dade County that included several different wastewater lution. As information on new classes of environmental reclamation treatment trains (e.g., with and without reverse contaminants arise, standard methods for assessing osmosis; ozone vs. ultraviolet/advanced oxidation processes), risk (e.g., whole effluent toxicity [WET] testing) may and trace organic chemical data were collected for several be unable to detect the subtle changes associated with months. However, the pilot project was halted in 2011 before these compounds. For instance, there have been recent the planned toxicity testing was initiated because of general concern about the economic feasibility of the larger ecological reports of treated wastewater causing severe lesions and restoration project (Jim Ferguson, Miami Dade County Water developmental alterations in amphibians, which are and Sewer Department, personal communication, 2011). not common sentinel testing organisms in the WET testing paradigm (Sowers et al., 2009; Keel et al., 2010; Ruiz et al., 2010). receiving water bodies. However, the level of toxicant Because stressors may be different between each exposure and dilution within the receiving systems reuse scenario, basic information on the effects of are key considerations when assessing toxicity. The potential ecological stressors in treated wastewater are individual constituents may arise from industrial, described in this chapter. household, or wastewater treatment plant applications.

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135 ECOLOGICAL ENHANCEMENT VIA WATER REUSE Nitrogen and Phosphorus BOX 8-2 Nutrients represent one of the historical problems Santa Clara Valley Water District (SCVWD) Stream Augmentation Project with direct discharge of wastewater effluent, although the nutrient discharge concentrations are highly de- SCVWD proposed a pilot project to augment the flows of pendent on the type of wastewater treatment provided Coyote Creek with advanced-treated reclaimed water from the (Carey and Migliaccio, 2009; see Box 8-2). EPA has San Jose/SCVWD treatment plant for the purpose of ecologi- recently focused increasing attention to the impacts of cal enhancement. Reclaimed water would be discharged into nutrients on surface water ecosystems and has encour- Upper Silver Creek 2 km upstream from its confluence with aged states to develop and adopt numeric nutrient Coyote Creek in San Jose and released from May to October at a flow rate of 1 to 2 cubic feet per second (cfs) (2,400 to 4,900 criteria for nitrogen and phosphorus (EPA, 2011).1 m3/d). Baseline studies were conducted prior to the project to Excess nutrients to an aquatic ecosystem can be prob- monitor water quality parameters (e.g. nutrients, oxygen, tem- lematic, because they cause an increase in the primary perature) and algal biomass (Hopkins et al., 2002). Hopkins et productivity of the ecosystem, known as eutrophication. al. (2002) concluded that augmentation to Coyote Creek could Eutrophication can lead to changes in dissolved oxygen result in increased nutrient and ammonia levels, as well as concentrations, algal blooms, decreases in submerged algal biomass. Analysis of advanced-treated wastewater (from treatment plants using dual-media filtration followed by disin- aquatic vegetation, and fish-kills. Increases in the limit- fection by either chlorination or chloramination) indicated that ing nutrient (i.e., the nutrient needed for plant growth it contained measurable levels of perfluorooctane sulfonate but which typically occurs in small quantities) will (PFOS) and perfluorooctanoate (PFOA) at total concentrations accelerate eutrophication. Typical levels of nitrate in ef- ≤ 470 ng/L (Plumlee et al., 2008). The bioaccumulation and fluents receiving secondary treatment with disinfection biomagnifacation factors for PFOS and PFOA that were used are between 5 and 20 mg nitrogen (N)/L. Typical levels in the ecological risk assessment of Coyote Creek were based on data obtained from the Great Lakes. Because the Great of phosphorus in effluents receiving conventional acti- Lakes and Coyote Creek are disparate water bodies, there vated sludge (i.e., secondary) treatment are 4–10 mg/L, were higher levels of uncertainty in the analysis of the risks of and these concentrations can be lowered to 1–2 mg/L PFOS and PFOA in Coyote Creek. Nonetheless, the detection with biological nutrient removal (BNR) (see Table 3-2). of these chemicals placed this project on hold in an attempt Ammonia is particularly toxic to aquatic organisms, to understand the meaning of these findings. with the toxicity dependent on pH and temperature. The roles of pH and temperature relate to the amount of un-ionized ammonia (NH3) in the water body. The a low pH increases the most toxic form (i.e., Cu2+) acute and chronic criteria for ammonia (pH 8 at 25°C) of copper. Hardness and copper toxicity are inversely are 2.9 and 0.26 mg/L, respectively (EPA, 2009a). proportional, whereby elevated water hardness leads Typical levels of ammonia in secondary effluents with to decreased copper toxicity (Erickson et al., 1996). disinfection are 1–10 mg/L and 1–3 mg/L with BNR Organic matter forms complexes with copper and re- (Asano et al., 2007). duces toxicity (Hollis et al., 1997). EPA has national water quality guidelines to protect aquatic life for most Metals metals, but site-specific parameters may need be con- sidered for ecological applications of reclaimed water Trace metals (cadmium, copper, etc) are common in sensitive ecosystems, particularly in areas with little regulated contaminants in wastewater discharges. The dilution of the wastewater discharge in the ecosystem toxicity of metals in aquatic systems is complex and (EPA, 2009a). is often related to the amount of dissolved or free The impact of silver- and titanium-based nanopar- metal in the water. Water quality parameters, such ticles in the aquatic environment is an emerging topic as hardness, pH, and organic matter, can greatly af- of research interest. Fabrega et al. (2011) reported that fect toxicity. When considering copper, for instance, concentrations of silver nanoparticles as low as a few nanograms per liter can affect fish and invertebrates, although mechanisms of toxicity, nanoparticle fate 1 S ee also http://water.epa.gov/scitech/swguidance/standards/ in wastewater treatment and the environment, and criteria/nutrients/strategy/index.cfm.

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136 WATER REUSE ecological risk in the environment remain poorly instance, dissolved oxygen acute mortality criteria for understood. non-embryo/early-life-stage freshwater fish is 3 mg/L (EPA, 1986). An increase in organism mortality and/or growth, in addition to changes in species composition, Salinity may be observed if dissolved oxygen levels fall below Changes in salinity may occur with the use of re- the developed criterion. claimed water. Typical levels of salt (measured as total dissolved solids [TDS]) in effluents receiving secondary Boron treatment with disinfection are 270–860 mg/L (Asano et al., 2007). Although the TDS of treated wastewater Boron, in the form of borates, is released into is not expected to be significantly greater than that of the environment from anthropogenic sources (i.e., many surface waters, ecological applications should wastewater treatment plant discharge), as well as from consider the TDS of the native water before introduc- weathering of sedimentary rocks (Frick, 1985; Howe, ing reclaimed water into existing ecosystems. Currently, 1998; Dethloff et al., 2009; see also Chapter 3). Boron no federal TDS aquatic life criterion exists (Soucek in reclaimed water is generally less than 0.5 mg/L, et al., 2011). However, site-specific criteria have been while concentrations in surface waters are generally ≤1.0 mg/L (Butterwick et al., 1989, Asano et al., 2007). advocated. For example, in certain regions of Alaska, a TDS criterion of 500 mg/L has been suggested for Fish, amphibian, invertebrate, and plant effects associ- periods of salmon spawning, while a TDS criterion ated with boron exposure generally occur in the low of 1,500 mg/L has been suggested for nonspawning to mid milligram-per-liter range (Powell et al., 1997; periods (Brix et al., 2010). Howe, 1998; Laposata and Dunson, 1998; Davis et al., 2002; Dethloff et al., 2009). The concentration of boron that affects fish, amphibians, invertebrates, and Temperature and Dissolved Oxygen plants, including landscape plants, are typically above Changes in water temperature may be associated the concentrations observed in reclaimed water (Wu with the use of reclaimed water for environmental and Dodge, 2005). purposes. Temperature can influence aquatic com - munity structure and productivity of microbes to fish. Trace Organic Chemicals For instance, water temperature has been shown to influence factors that affect growth in aquatic organ- As discussed in Chapter 3, trace organic contami- isms (e.g., metabolic rate, respiration), which may alter nants (e.g., pharmaceuticals and personal care products, community structure and trophic interactions (i.e., and flame retardants) have been detected in municipal predator-prey dynamics) within a water body (Sobral wastewater effluent and in the nation’s surface waters, and Widdows, 1997; Abrahams et al., 2007; Hoekman, creating concerns for both human and aquatic systems 2010). Further, temperature can alter aquatic habitat (Daughton and Ternes, 1999; Kolpin et al., 2002; see influencing species composition and biodiversity ( Jones also Appendix A). The presence of these chemicals et al., 2004). Typically, the temperature of treated (e.g., carbamazepine, triclosan, brominated diphenyl wastewater discharge is in the normal range of the ethers) is associated with normal human use of trace receiving environment. organic compounds. When considering the sensitiv- Dissolved oxygen is an important parameter for ity of human and aquatic organisms to trace organic aquatic life and is related to various water quality compounds detected in reclaimed water, it is important parameters including temperature. As temperature to note that aquatic organisms are generally as sensi- increases in a water body, dissolved oxygen decreases. tive or more sensitive than humans to these chemicals Dissolved oxygen can also be reduced by algal blooms (Table 8-1). Further, the potential toxicity for many of spurred by high nutrient concentrations. National and these compounds may be heavily influenced by water site-specific dissolved oxygen criteria have been de- quality parameters (e.g., pH), thus complicating the veloped to protect aquatic life (EPA, 1986, 2000). For risk assessment process described below (Valenti et al.,

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137 ECOLOGICAL ENHANCEMENT VIA WATER REUSE TABLE 8-1 Comparison of Human Monitoring Trigger Levels for Potable Reuse and Aquatic Predicted No Effect BOX 8-3 Concentrations for Selected Chemicals in Reclaimed 17-α Ethinyl Estradiol: A Case in Water Ecological Endocrine Disruption Example Predicted Natural and synthetic chemicals have the ability to mimic Occurrence Human No Effect endogenous hormones, alter the endocrine system, and lead in Secondary/ Monitoring Concentrations Advanced- Trigger (PNECs) to reproductive dysfunction in aquatic organisms. In particular, Treated Water Levels for Aquatic numerous studies have focused on the toxicity associated with (ng/L)a,b Chemical (ng/L)b Ecosystems (ng/L)c the birth control contraceptive 17-α ethinyl estradiol (EE2) in ≤1 Ethinyl Estradiol 280 0.35 fish (Lange et al., 2001). Fish reproduction is the most sensi- Carbamazepine 400 1,000 250,00 tive end point associated with EE2, with a laboratory predicted Fluoxetine 31 10,000 1,400 no effect concentration of 0.35 ng/L (Caldwell et al., 2008). PFOS 90 200 1,200 A whole Canadian lake study was conducted with EE2, where Triclosan 485 350 69 lakes treated with 5–6 ng/L EE2 caused population declines DEET 1,520 2,500 7,700 Atenolol 1,780 70,000 1,800 in fathead minnows and other organisms (Kidd et al., 2007). Nonylphenol 161 500,000 1,700 Although these data supported the laboratory findings of aDefined as the 90th percentile average occurrence in secondary or EE2, the levels are higher than those normally expected in the advanced-treated wastewater, representative of water quality required by environment (Hannah et al., 2009). California’s Title 22 regulations for urban irrigation (Drewes et al., 2010). bCalculated from risk-based acceptable daily intakes (ADIs; see Chapter 6 and Box 6-5) in the California State Water Resources Control Board (SWRCB) Science Advisory Panel Report (Drewes et al., 2010). To date, few field studies have evaluated the impact that cDerived by methods outlined under Single Chemical Risk Assessment in this chapter using Brooks et al. (2003); Cleuvers (2003); EPA (2005b); water reuse and associated trace organics may have on Beach et al. (2006); Costanzo et al. (2007); Caldwell et al. (2008); Capdevi- the environment. In addition, few studies are available elle et al. (2008); Küster et al. (2010). linking the relationship of laboratory endocrine and reproductive responses to effects in natural systems. 2009). Human health impacts related to trace organic Although endocrine disruption is a major scientific contaminants are discussed in Chapters 6 and 7. research thrust, the detection and risk of endocrine Natural and synthetic chemicals have the ability to disruptors may be different depending on the reuse mimic endogenous hormones and alter the endocrine scenario. Atkinson et al. (2009) and Slye et al. (2011) system in aquatic organisms. Chemicals that alter the investigated surfactants along a 100-mile gradient on endocrine system may ultimately cause reproductive the Trinity River spanning the Dallas-Fort Worth dysfunction and population-level decline of organisms. Metroplex to Palestine, Texas, where in some areas in the summer months >95 percent of the flow comes W hile there are a myriad of chemicals that may interact and disrupt the endocrine system (e.g., bisphenol-A, from municipal wastewater effluent from multiple in- cadmium), one of the best-studied endocrine disruptors puts. No risk to aquatic organisms could be attributed is the birth control contraceptive 17-α ethinyl estradiol to surfactants associated with this effluent-dominated (EE2; see Box 8-3; Lange et al., 2001; Maunder et al., river. These two studies represent examples for how 2007). The science is still developing with respect to geographic information systems (GIS) and chemical biological assay for rapid detection of endocrine disrup- and biological monitoring can be incorporated to evalu- tors (discussed later in this chapter). ate an ecosystem dominated with effluent. One of the current limitations in evaluating the ecological risk of trace organics relates to the amount APPROACHES FOR ASSESSING of ecotoxicity data available. For many trace organics, ECOLOGICAL RISKS OF few data are available to make a reliable assessment RECLAIMED WATER of risk. With respect to pharmaceuticals, for instance, the recent improvement in the European Medicines Many questions remain about the risk of trace or- Agency guidelines for the environmental risk assess- ganic chemicals to the environment because of the lack ment of pharmaceuticals should reduce these data gaps. of associated environmental fate and effects informa-

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138 WATER REUSE tion. Historically, most chemicals have been tested one testing. However, if no data are available for the con- chemical at a time. However, mixtures of bioactive trace taminants or end points of interest, then testing may be organic chemicals are often present in water, for which necessary (described in the following sections). new techniques need to be developed and refined to Once risk exposure and effects analysis are com- better understand their risk to the environment. As de- pleted, a predicted environmental concentration (PEC) scribed in Chapter 6, a mixture of chemicals may result and a predicted no-effect concentration (PNEC) for in toxicity that is equal to, less than, or greater than the the stressors will be available. The PEC/PNEC ratio sum total of the toxicity of the individual components. will determine the risk associated with the stressors. If the PEC/PNEC ratio is ≥1, then a risk exists to Using chemicals with the same mode of action (e.g., the environment. A ratio that is < 1 suggests that the environmental estrogens), it has been demonstrated that the combined toxicity could be predicted based potential risk to the environment is low. If adequate on the toxicity of the individual chemicals (Thorpe et data are available to calculate a species sensitivity dis- al., 2003). However, it is much more difficult to model tribution, a more extensive probabilistic environmental mixture responses when the modes of action of the risk assessment approach may be used to estimate the individual chemicals within the mixture are different. likelihood and the extent of adverse effects occurring This section discusses historical as well as newer tech- ( Verdonck et al., 2003). niques that can be used to assess ecological risk even in the absence of chemical-specific data. Single Chemical Risk Assessment The ecological risk assessment (ERA) process is adapted from and is not dissimilar to the human The environmental safety of chemicals is most of- health risk assessment process described in Chapter 6. ten assessed on an individual basis, irrespective of the An ERA consists of four phases: problem formulation, fact that in the aqueous environment there is a mixture characterization of exposure, characterization of effects, of chemicals. In a single chemical assessment scheme, and risk characterization (EPA, 1998a). Following the a n o-observed effect concentration (NOEC), the risk characterization phase, the information can be used lowest-observed effect concentration (LOEC), and/or an effective concentration (EC)2 will be derived in a by risk managers to determine the course of action for the particular action or question. Furthermore, the data series of laboratory studies with fish, algae, and inver- can be used to prioritize which chemicals are of greatest tebrates. Typically, these studies focus on higher level concern and deserve further research. end points such as survival, growth, and reproduction An ERA is typically conducted to evaluate the like- of the test organisms. Both the EPA and the Organi- lihood of adverse effects in the environment associated sation for Economic Co-operation and Development with exposure to chemical, biological, or physical stress- have defined methodological protocols to conduct these ors (EPA, 1998a). In addition, the ERA is designed to studies (EPA, 2010d; OECD, 2011). In the case of fish accommodate mixtures of stressors on aquatic life and and invertebrates, the first studies that are conducted are acute or short-term assays, which are ≤96 hours habitat. In this respect, it can be used as the founda- tion for determining potential adverse effects of using and focus on the concentration that causes 50 percent reclaimed water for ecological purposes. Key factors in mortality in the test organisms (lethal concentration 50 the ERA are the end point to be evaluated (e.g., habitat, percent; LC50). Following these initial mortality stud- ies, chronic reproduction and growth studies (≥21 days) endangered species) and the sensitivity of the ecosys- tem, which may be different for each reuse scenario. are often conducted with fish and invertebrates. Once Once the end points of concern have been identi- fied, an understanding of the magnitude of exposure 2 Effective concentration (ECx) is the concentration of a toxicant and response to the stressors will ultimately determine that produces X percent of the maximum physiological response. the level of risk. One of the first and fastest approaches For example, an EC50 reflects the concentration that produces half will be to conduct a literature evaluation based on the of the maximum physiological response after a specified exposure time. NOEC and LOEC are the ecological risk parallels of the stressors of interest to determine if aquatic toxicity or lowest observed adverse effect level (LOAELs) and no observed water quality criterion data are available. If data are adverse effect level (NOAEL) for human health risk assessment as available, the assessment may be done without further defined in Box 6-5.

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139 ECOLOGICAL ENHANCEMENT VIA WATER REUSE a NOEC is obtained, a safety/uncertainty factor is ap- BOX 8-4 plied, accounting for species and exposure differences, Assessing the Ecological Risk of to derive the PNEC. These data can be useful in the Carbamazepine: Two Approaches assessment of reclaimed water because one can compare the PNEC values to the concentrations measured in the Carbamazepine is an antiepileptic drug marketed in North water (see Table 8-1). America and Europe. Approximately 17 percent of an ingested Note that in this single-chemical assessment dose is eliminated from humans as nonmetabolized carba- scheme, the data are usually obtained in controlled mazepine. Using the traditional ecological risk assessment approach, the potential ecological risk can be estimated. The laboratory settings and do not focus on community predicted environmental concentration (PEC) for carbamaze- and ecosystem attributes (e.g., nutrient cycling). Once pine based on modeling approaches is estimated to be ≤0.658 the chemical is released into the environment, there μg/L (Cunningham et al., 2010), while the 90th percentile may be interactions with other substances, such as dis- occurrence in reclaimed water meeting California’s urban solved organic carbon, that may modulate its toxicity, irrigation requirements (Title 22) is <0.400 μg/L (CSWRCB, in addition to potential interaction with other chemical 2010). To determine the PNEC, a wide array of available eco- toxicity data are assessed. The 96-hr LC50 values for Daphnia contaminants. Laboratory studies do not account for magna (invertebrate) and Japanese medaka (fish) are 76 and mixture interactions, where these interactions may lead >100 mg/L, respectively (Kim et al., 2007). The 72-hr algal to additive or greater-than-additive toxicity. Although effective concentration 50 percent (EC50; the concentration laboratory studies can be conducted to evaluate mix- that produces a response halfway between the baseline and tures, it is unreasonable to assume that every realistic the maximum response) is 74 mg/L, while the 7-day duckweed mixture component can be studied. These sources of growth EC50 was 25 mg/L (Cleuvers, 2003). Duckweed growth appears to be the most sensitive end point and because only uncertainty with respect to potential toxicity need to acute data are available, a safety factor of 1,000 is applied to be recognized. Safety or uncertainty factors can be ap- the EC50 value. The resultant PNEC is 25 μg/L. Performing plied with the risk assessment process to account for the risk quotient calculation (PEC/PNEC), the risk is <0.03, mixture scenarios. indicating that adverse environmental effects are not expected A single chemical risk assessment approach is in surface waters augmented with reclaimed water. used for most trace organic chemicals, including phar- The potential environmental risk can also be estimated using the mammalian model screening approach (Huggett maceuticals and personal care products (see Box 8-4 et al., 2003). This approach represents a rapid screening for an example application of this method). In this method to estimate ecological risks based on the large quan- single-chemical approach, molecular, biochemical, and tity of mammalian effects data available for pharmaceuticals. physiological end points are not utilized because they Considering the predicted environmental concentration of are often difficult to link to higher level effects (e.g., carbamazepine of ≤0.658 μg/L and an octanol water coefficient survival, growth, and reproduction). (log Kow) of 1.68 (Cunningham et al., 2010), the resultant fish plasma concentration is calculated as 2.6 μg/L. The human In the case where a PEC/PNEC ratio is >1 and therapeutic plasma concentration for carbamazepine is 2,170 the body of information suggests that a chemical may μg/L after a single administration (Revankar et al., 1999). The adversely affect the environment, controlled outdoor calculated fish plasma concentration at estimated environ- pond or stream mesocosm experiments will help to mental concentrations of carbemazepine is much less than better predict its impact on populations, communities, the plasma concentration known to exhibit effects in humans. and ecosystems. This approach was used by Kidd et al. Therefore, the environmental risk to fish is estimated to be low. The mammalian model screening approach yielded the (2007) to demonstrate that 17α-ethinyl estradiol can same conclusion as the traditional risk assessment approach, cause population- and community-level impacts at suggesting its utility in rapid screening of environmental risk environmentally relevant concentrations. The benefit of associated with pharmaceuticals. these studies is that one can measure end points (e.g., species density, species richness, nutrient cycling) in a controlled exposure scenario. In addition, mesocosm experiments have been conducted where a single con- An immense amount of mammalian pharmaceuti- taminant has been introduced into a complex effluent cal data (e.g., toxicological impacts, pharmacokinetics, to evaluate potential mixture interactions (Brooks et and metabolism, often in multiple organisms) may be al., 2004). helpful in screening potential environmental risks asso-

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140 WATER REUSE ciated with pharmaceuticals (Lange and Dietrich, 2002; BOX 8-5 Huggett et al., 2003, 2004). A recent analysis indicated Bioconcentration and Bioaccumulation of that many human pharmaceutical therapeutic targets Perfluorooctane sulfonate (PFOS) are present in fish (Gunnarson et al., 2008). If the therapeutic targets are similar across species, then the PFOS has multiple commercial uses (e.g., stain repel- internal concentrations that elicit effects across species lant) and has been detected in wastewater and reclaimed may be similar. Knowing the PEC of a pharmaceutical water (Plumlee et al., 2008). The log Kow for PFOS is 4.4, and and its relative hydrophobicity (or aversion to water, as laboratory fish BCF values range from 210 to 5,400, which indicate that this substance is potentially bioaccumulative measured by the octanol-water coefficient, Kow), a fish (Martin et al. 2003; EA, 2004; Ankley et al., 2005). Multiple plasma concentration of that pharmaceutical may be field studies have measured concentrations of PFOS in in- calculated. This value can then be compared to the hu- vertebrates and fish at concentrations greater than that in the man therapeutic plasma concentration (HTPC), which surrounding environment (Kannan et al., 2005; Li et al., 2008). is the concentration of that drug in plasma known to Concentrations of PFOS have also been measured in eagles cause an effect. If the fish plasma concentration exceeds and mink from the Great Lakes region at concentrations 5–10 times greater than in their respective prey items (Kannan et the plasma concentration known to cause biological ef- al., 2005). Given that PFOS has been measured in reclaimed fects in humans, then the concentration of the drug in water, these data indicate that PFOS has the potential to move the water should be suspected of causing an ecological through the food chain in areas where reclaimed water is effect. This model can quickly help prioritize ecologi- being used for environmental enhancement. The major U.S. cal risk associated with pharmaceuticals and identify manufacturer of PFOS has announced a voluntary phase-out specific drugs that should undergo further testing prior of PFOS from commerce (EA, 2004). to ecological reuse applications (Box 8-4) (Huggett et al., 2003, 2004; Schreiber et al., 2011). Bioconcentration and Bioaccumulation Effluent Toxicity Testing and Monitoring Since the publication of Silent Spring by Rachel A number of toxicity testing and biomonitoring Carson in 1962, the bioaccumulation of chemicals methods are available to assess the ecological effects of in the environment has received growing attention. reclaimed water for ecological applications. These can Bioconcentration has traditionally been defined as be divided into conventional, state-of-the-science, and the accumulation of chemical substances from aquatic blended approaches. environments through nondietary routes, whereas bioaccumulation is the accumulation from nondietary Conventional Approaches: Whole Effluent Toxicity Tests and dietary routes (Barron, 1990). EPA has established criteria where a bioconcentration factor (BCF) or a bio- The WET testing program in the United States accumulation factor (BAF) > 1,000 (i.e., concentration was implemented to protect water bodies from point- in organisms 1,000× greater than water or food) must source municipal and industrial discharges (Heber et undergo further testing. Substances with a BCF or al., 1996). WET programs for wastewater facilities BAF >5,000 may be banned from commerce (Moss and typically consist of whole-effluent bioassays to deter- Boethling, 1999) (Box 8-5). Several studies have shown mine whether the discharges are affecting the receiving a relationship between BCF and KOW (Barron, 1990), waters (Heber et al., 1996). Typical WET laboratory where a log KOW > 3 requires additional consideration. bioassays include acute invertebrate and fish survival Both laboratory and field studies at multiple trophic studies, subchronic fish growth studies, and chronic in- levels (e.g., fish, birds) can indicate if a chemical is po- vertebrate reproduction studies. These tests can also be tentially bioaccumulated or bioconcentrated, although conducted to determine ecological responses to a single field measurements may be needed to confirm labora- contaminant or specific mixtures. The typical duration for most of these studies is <7 days. Field assessments tory findings (OECD, 1996; Weisbrod et al., 2009).

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141 ECOLOGICAL ENHANCEMENT VIA WATER REUSE of invertebrate and/or fish population and community of vitellogenin in the liver, where it is released into the structure can also be part of WET programs, but these blood for incorporation in eggs. Chemicals that act as assessments are not as frequent as laboratory testing. estrogen mimics (e.g., nonylphenol) increase vitello- genin production in fish, especially in male fish which only produce small quantities under normal conditions. State of the Science V itellogenin production, in either whole fish or liver While traditional ecotoxicology has focused on cells, can therefore be used to evaluate estrogen content survival, growth, and reproduction as the main deter- in municipal effluent, surface waters, and reclaimed minants of risk (e.g., WET testing), knowledge regard- waters. Filby et al. (2010) utilized vitellogenin as the ing the toxic modes of action (i.e., how the chemicals primary method to determine the extent of estrogen manifest their toxicity) has expanded available toxicity c ontent reduced by various wastewater treatment testing alternatives, including in vivo biomarkers or in technologies. vitro bioassays. These in vivo and in vitro markers may Another promising nonspecific approach is through be specific or nonspecific for a class of chemicals. the use of gene expression profiling. Fish or other In the past several decades, researchers have dis- aquatic organisms are exposed to the water of interest, covered that chemicals in the environment may interact and the differential regulation of genes in the liver or with the normal estrogen, androgen, and thyroid sig- gonad is determined (Garcia-Reyero et al., 2008). The naling pathways in aquatic organisms (i.e., endocrine analysis can help determine which biological pathways disruption) (Desbrow et al., 1998; Rodgers-Gray et and processes, if any, are being altered by the water sam- al., 2001; Sumpter and Johnson, 2008). Through in ple. Efforts are currently under way to bridge changes vitro and in vivo screening of wastewater effluents (pri- in biological pathways to adverse outcomes (termed mary, secondary, and advanced secondary), researchers adverse outcome pathways) at higher levels of biological discovered that chemicals can interact directly with organization, as well as develop genomic fingerprints hormone receptors (e.g., estrogen receptors) and that for individual and chemical-specific classes (Kramer et these chemicals can induce changes in the fish egg yolk al., 2011). An understanding of pathway data may be precursor vitellogenin (Desbrow et al., 1998). Desbrow useful in developing new in vitro screening methodolo- et al. (1998) were unable to identify a relationship gies for chemicals of interest. between the various wastewater treatment effluents studied (including primary, activated sludge, percolat- Blended Approaches ing filters, and sand filters) and vitellogenin produc- tion. From this knowledge, the yeast estrogen (YES) Conventional testing methodologies (e.g., WET) and yeast androgen receptor assays were developed focus on higher level biological end points (i.e., growth, for screening purposes (Arnold et al., 1996). These survival, reproduction). Research with endocrine- assays investigate the binding of aqueous chemicals disrupting chemicals demonstrates that some of these to the estrogen or androgen receptors in yeast cells via methodologies (e.g., invertebrate reproduction) may colorimetric measurements. Ultimately, researchers can not be sensitive enough to detect subtle biological determine the extent to which estrogenic or androgenic changes that may take months or years to generate, chemicals are present in water. For instance, Holmes while other responses (e.g., fish reproduction) offer et al. (2010) utilized the YES assays to demonstrate more sensitive end points (Länge et al. 2001). The a 97 percent reduction in total estrogenic activity in a yeast screening, vitellogenin, and gene profiling assays reclaimed water treatment system that utilizes stabili- offer the ability to generate screening-level biologi- zation lagoons followed by coagulation, dissolved air cal data quickly to determine the presence and/or the flotation/filtration, and chlorination. relative levels of biologically active compounds in the Vitellogenin production is directly linked to matrix of interest. However, there is a need for assay s timulation of the estrogen receptor. Circulating standardization and training in order to achieve reli- 17β-estradiol in female fish stimulates the production able results. There is also potential with some of these

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142 WATER REUSE assays (e.g., YES) for false-positive or false-negative BOX 8-6 results. Further, it should be recognized that at this time Water Quality Criterion for Nonylphenol: there is no direct link to higher level measurements United States vs. European Union (e.g., reproduction). Neither binding of a chemical to a receptor, induction of vitellogenin, nor changes in Nonylphenol is a frequently detected wastewater contami- gene expression are conclusive of a population effect. nant, most commonly used to produce nonionic surfactants. They do, however, strongly suggest that more research In 1998, 104 million kg of nonylphenol was produced in the is needed. United States (Harvilicz 1999). EPA has established ambi- ent water quality criteria for nonylphenol in both saline and Because of the advantages and shortcomings with freshwater systems. The acute and chronic freshwater quality each conventional and state-of-the-science methodol- criteria are 28 and 6.6 μg/L, respectively, while the acute and ogy, researchers are utilizing a blended approach incor- chronic saltwater criteria are 7 and 1.7 μg/L, respectively. porating both methodologies (Steinberg et al., 2008). Aquatic organism survival, growth, and reproduction end Deng et al. (2008) utilized an online, flow-through fish points were used to establish these criteria. Although non- exposure system with reproductive, endocrine (vitel- ylphenol has been demonstrated to cause estrogenicity in aquatic organisms (e.g., causes fish to produce vitellogenin), logenin), and other end points to assess the ecological these data do not meet the acceptability requirements for water effects of shallow groundwater recharged by reclaimed quality criteria by the EPA (EPA, 2005b). Therefore, these data water in the Santa Ana River Basin, California. The were not utilized in establishing the criteria. In contrast, the advantage of using a blended monitoring system is European Union has restricted marketing and use of nonyl- that one can achieve the rapid screening-level data as- phenol based in part on the potential for nonylphenol to be an sociated with the newer assays, as well examine higher estrogenic substance. The European Union risk assessment for nonylphenol cited a PNEC of 0.33 μg/L, based on a long- level end points. term algal study. Further, the resultant nonylphenol PEC/PNEC The difference in ecological risk analysis using ratio was determined to be 1.8 (European Union, 2002). conventional vs. more state-of-the-science techniques is evident when one considers nonylphenol (Box 8-6). For nonylphenol, EPA developed ambient water crite- ria using conventional toxicity testing methods, while exceed those encountered with the normal surface the European Union utilized new scientific methods water discharge of municipal wastewater. The most (Box 8-6). probable ecological stressors include nutrients and trace organic chemicals, although stressors could also include CONCLUSIONS AND RECOMMENDATIONS temperature and salinity under some circumstances. Currently, few studies have documented the en- For some of these potential stressors (e.g., nutrients) vironmental risks associated with the purposeful use there is quite a bit known about potential ecological of reclaimed water for ecological enhancement. Wa- impacts associated with exposure. Based on the avail- ter reuse for the purpose of ecological enhancement is a able science, there is no reason to believe that the use relatively new and promising area of investigation, but of reclaimed water for environmental enhancement few projects have been completed and the committee purposes would pose greater impacts than those already was unable to find any published research in the peer- occurring in many of the nation’s surface waters im- reviewed literature investigating potential ecological pacted by wastewater discharge. Further, the presence effects at these sites. As environmental enhancement of contaminants and potential ecological impacts may projects with reclaimed water increase in number and be lower if additional levels of treatment (e.g., nutrient scope, the amount of research conducted with respect removal, ozone) are applied. Trace organic chemicals have raised some con- to ecological risk should also increase, so that the po- cerns with ecological enhancement projects, because tential benefits and any issues associated with the reuse aquatic organisms can be more sensitive to trace application can be identified. The ecological risk issues and stressors in eco- organic chemicals than humans. A lthough other logical enhancement projects are not expected to stressors are well understood and treatment systems can

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143 ECOLOGICAL ENHANCEMENT VIA WATER REUSE water. Although conventional methods (e.g., WET) be developed to reduce their concentrations to accept- able levels, less is known about the ecological effects of of monitoring can be used, newer, more rapid and trace organic chemicals, including pharmaceuticals and sensitive methods of biological screening (e.g., YES) personal care products. Endocrine disruption has been, are available. However, the limitations of these assays and will likely continue to be, a scientific research area should be recognized, and as the science develops, these and concern. More data are needed to link population limitations will likely be reduced. Site-specific consid- level effects in natural aquatic systems to laboratory erations (e.g., species present, habitat, geology) and a observations. priori knowledge regarding specific contaminants of Sensitive ecosystems may necessitate more rig- concern (e.g., endocrine disruptors) may suggest a more orous analysis of ecological risks before proceeding sophisticated testing program, involving field-based with ecological enhancement projects with reclaimed testing combined with lab-based bioassays.

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