Publicly Owned Treatment Works Research Articles

Bioaugmentation in Leachate Treatment: Enhancing Ammonia Nitrogen Elimination in US Landfills

Purpose: This research seeks to assess the quantitative effects of implementing bioaugmentation solutions within existing landfill leachate management systems. The study involves the analysis of different sites to gauge the influence on leachate composition, considering various industry management practices such as lagoons, tanks, sewer discharge, or off-site trucking. The primary objective is to examine changes in microbial communities within the leachate, specifically focusing on their impact on ammonia nitrogen elimination rates. The ultimate goal is to achieve lower levels of ammonia nitrogen before the discharge of leachate to publicly owned treatment works (POTW).Methodology: The research employs a comprehensive methodology that involves the examination of diverse landfill sites utilizing various industry management practices for leachate treatment. The analysis includes assessing leachate composition and the study evaluates effectiveness of bioaugmentation in enhancing ammonia elimination rates, considering different leachate treatment approaches and operating conditions. This involves a systematic comparison of outcomes across sites and management practices.Findings: The findings of this study indicate that bioaugmentation is an effective strategy for accelerating ammonia elimination rates in landfill leachate. The analysis reveals notable improvements in microbial communities, leading to reduced levels of ammonia nitrogen in the leachate prior to its discharge to POTW. The study highlights the versatility of bioaugmentation across different industry management practices, showcasing its potential benefits under varying operating conditions and treatment setups.Unique contributor to theory, policy and practice: Based on the study's outcomes, it is recommended that landfill operators and leachate management practitioners consider implementing bioaugmentation solutions to expedite ammonia elimination rates. The findings suggest that bioaugmentation is a cost-effective and fast-to-deploy solution that requires negligible capital expenditure. This approach has the potential to generate significant savings, especially in the face of a more stringent regulatory environment. The recommendations emphasize the adaptability and efficiency of bioaugmentation across a broad range of operating conditions within existing landfill leachate management infrastructure.

Fifty-Year Review of Effluent Discharge Trends to the Southern California Bight from Large Municipal Wastewater Treatment Facilities from 1971 to 2020

Historically, Southern California’s four largest publicly owned treatment works (POTWs) were major sources of contaminants in the Southern California Bight (SCB), home to over 22 million residents and diverse marine life. This study conducted a fifty-year review (1971–2020) to assess these facilities’ performance in protecting human and aquatic life. We analyzed effluent discharge flow, total annual mass emissions into SCB, and the rate of change of mass emissions in five ten-year timeframes. Results show a significant decrease in contaminant concentrations (43% to 99%) from 1971 to 2020, with most reaching historically low levels. Despite a growing population, effluent volume decreased by 23%, reflecting successful local water conservation and recycling efforts. Some constituents experienced temporary increases that later decreased. Overall, the decline in mass emissions for all constituents over fifty years highlights the POTWs’ efforts to treat effluent and reduce their impact on the SCB’s ecosystem.

Divergence of wastewater SARS-CoV-2 and reported laboratory-confirmed COVID-19 incident case data coincident with wide-spread availability of at-home COVID-19 antigen tests.

Concentrations of SARS-CoV-2 RNA in wastewater settled solids from publicly owned treatment works (POTWs) historically correlated strongly with laboratory confirmed incident COVID-19 case data. With the increased availability of at-home antigen tests since late 2021 and early 2022, laboratory test availability and test seeking behavior has decreased. In the United States, the results from at-home antigen tests are not typically reportable to public health agencies and thus are not counted in case reports. As a result, the number of reported laboratory-confirmed incident COVID-19 cases has decreased dramatically, even during times of increased test positivity rates and wastewater concentrations of SARS-CoV-2 RNA. Herein, we tested whether the correlative relationship between wastewater concentrations of SARS-CoV-2 RNA and reported laboratory-confirmed COVID-19 incidence rate has changed since 1 May 2022, a point in time immediately before the onset of the BA.2/BA.5 surge, the first surge to begin after at-home antigen test availability was high in the region. We used daily data from three POTWs in the Greater San Francisco Bay Area of California, USA for the analysis. We found that although there is a significant positive association between wastewater measurements and incident rate data collected after 1 May 2022, the parameters describing the relationship are different than those describing the relationship between the data collected prior to 1 May 2022. If laboratory test seeking or availability continues to change, the relationship between wastewater and reported case data will continue to change. Our results suggest, assuming SARS-CoV-2 RNA shedding remains relatively stable among those infected with the virus as different variants emerge, that wastewater concentrations of SARS-CoV-2 RNA can be used to estimate COVID-19 cases as they would have been during the time when laboratory testing availability and test seeking behavior were at a high (here, before 1 May 2022) using the historical relationship between SARS-CoV-2 RNA and COVID-19 case data.

Design of Electrochemical Cells for Targeted Metals Removal Using Carbon Electrodes

Selective separations are needed in a wide variety of industrial and commercial applications where discharge to publicly owned treatment works (POTW) requires certain metals concentrations to be sufficiently low to protect public health and the surrounding environment. Metals such as lead (Pb), copper (Cu), chromium (Cr), nickel (Ni), zinc (Zn), and cadmium (Cd) represent a non-exhaustive list of compounds requiring removal for discharge regulations. Typically, coagulants such as iron and aluminum combined with precipitation chemistry or ion exchange processes are used to meet these regulations.1 However, these methods are not particularly selective and can produce sizable sludge waste that must be disposed of properly. Size-selective membranes are one alternative approach, but the pretreatment requirements for these membranes further complicates the water treatment process. Capacitive deionization (CDI) is an emerging water treatment option as well with notable advances in recent years, but it currently lacks the selectivity needed for many industrial streams.2 Therefore, alternative methods are being sought to realize these separations.The use of electrochemical processes offers a number of benefits such as a defined interface for interaction with the metal of interest, the ability to modulate the interface easily and quickly through changes in localized voltage, use of the electrical current to monitor system conditions, and the in situ generation of chemical species that can aid in the separation. Of particular interest in a wide variety of industrial applications is the removal or Cu from water being discharged to the POTW. Cu is found in waste streams emanating from electroplating, electronics, semiconductor, and battery manufacturing operations. While coagulation approaches mentioned above can often be used to meet effluent regulations, metal recovery through an electrochemical process can be highly effective and efficient, reaching current efficiencies in excess of 95% in many applications. The ability to plate Cu at a cathode under highly localized conditions affords the removal of Cu down to levels <100 ppb. Electrowinning has been used for over a century in the creation of purified metals such as Cu, so the concept is not entirely new, but the design of electrode materials and overall cell construction capable of removing Cu to such low concentrations in streams that have conductivities <1 mS/cm opens up new avenues for water treatment in industrial and commercial waste.In this talk, electrochemical cell design and operation as well as feed water conditions will be reviewed towards the development of selective metal removal technologies. Copper removal will be highlighted as an example, but the concept will also be applied to other metals of interest, demonstrating the more ubiquitous nature of the approach.

SARS-CoV-2 RNA is enriched by orders of magnitude in primary settled solids relative to liquid wastewater at publicly owned treatment works.

Wastewater-based epidemiology has gained attention throughout the world for detection of SARS-CoV-2 RNA in wastewater to supplement clinical testing. Raw wastewater consists of small particles, or solids, suspended in liquid. Methods have been developed to measure SARS-CoV-2 RNA in the liquid and the solid fraction of wastewater, with some studies reporting higher concentrations in the solid fraction. To investigate this relationship further, six laboratories collaborated to conduct a study across five publicly owned treatment works (POTWs) where both primary settled solids obtained from primary clarifiers and raw wastewater influent samples were collected and quantified for SARS-CoV-2 RNA. Settled solids and influent samples were processed by participating laboratories using their respective methods and retrospectively paired based on date of collection. SARS-CoV-2 RNA concentrations, on a mass equivalent basis, were higher in settled solids than in influent by approximately three orders of magnitude. Concentrations in matched settled solids and influent were positively and significantly correlated at all five POTWs. RNA concentrations in both settled solids and influent were correlated to COVID-19 incidence rates in the sewersheds and thus representative of disease occurrence; the settled solids methods appeared to produce a comparable relationship between SARS-CoV-2 RNA concentration measurements and incidence rates across all POTWs. Settled solids and influent methods showed comparable sensitivity, N gene detection frequency, and calculated empirical incidence rate lower limits. Analysis of settled solids for SARS-CoV-2 RNA has the advantage of using less sample volume to achieve similar sensitivity to influent methods.

Comparative stability of assay results of enterococci measured by culture and qPCR over time in bathing beach waters

The diurnal presence of the culturable bacterial indicators of fecal contamination in the water environment has been shown to be highly variable over time due to natural die-off and injury from effects of sunlight and other environmental stressors. Molecular analytes of a quantitative polymerase chain reaction (qPCR) method for measuring fecal contamination degrade considerably slower than the alternative of culturable fecal indicator bacteria. The rapid qPCR method holds the promise of more timely notification decisions with respect to postings or closure being made on the basis of microbial water quality samples collected earlier on the same day. In the case of culture-based methods requiring a 24 h or longer incubation period, decisions must be based on samples collected no sooner than the previous day. To examine the effect of this lag in assay results, temporal stability of a molecular Enterococci target analyte with that of traditional culture-based cells is compared using data from USEPA studies conducted between 2003 and 2007 on seven freshwater and marine beaches that were impacted by publicly-owned treatment works. Generally, levels of the molecular indicator were more consistent throughout the day between 8:00 am and 3:00 pm. The difference in temporal consistency is even more pronounced when the 24-h lag in culture-based results is taken into account.

Evaluation of the effects of chemically enhanced primary treatment on landfill leachate and sewage co-treatment in publicly owned treatment works

This study evaluated the effects of Chemically Enhanced Primary Treatment (CEPT) on co-treatment of landfill leachate and sewage in publicly owned treatment works (POTWs). Two most frequently used coagulants in CEPT, ferric chloride and aluminum sulphate, were studied. Bulk organic matter, pH variation, UV absorption, etc. were evaluated during the treatment processes. 54 %–74 % organic matter removal was achieved by ferric and aluminum coagulants. Ferric coagulant was found to perform better for organic matter removal than aluminum in most cases. Notably, ferric chloride coagulation increased the UV absorbance of treated leachate significantly by up to 10 times, while aluminum sulphate only slightly decreased it. Theoretical models are discussed to elucidate co-precipitation behaviors under various pH scenarios. It is exacerbated by the complexes formed by ferric and organic matter, which have characteristic light absorption in the UV range. The formation of such complexes is supported by the Fourier Transform Infra-Red (FTIR) spectroscopy. In addition, the volatile acids in leachate were found to play an important role in mediating pH through their buffering capacity.

Comparison of Coal-, Coconut-, and Wood-Based Activated Carbons for Removal of Organic Matters in Wastewater Treatment Plant Effluent

Objectives : This study investigated the removal of dissolved organic materials by coal-, coconut-, and wood-based activated carbons to assess the addition of an activated carbon process to a publicly owned treatment works (POTW).Methods : We assessed the removal of total organic carbon (TOC) by each process in the POTW, and examined the removal of TOC and UVA254 upon adding different amounts of coal-, coconut- and wood-based activated carbons (50, 100, 200, 300, and 400 mg/L) with various contact time (10, 20, 30, 60, 120 min).Results and Discussion : Approximately 80% of TOC was removed throughout the POTW compared to the influent. The activated carbon adsorption tests of coagulated wastewater revealed that the removal rate of TOC and UVA254 from coal-based activated carbon was higher than those of coconut-based and wood-based activated carbons. The removal rate of dissolved organic materials was highest in ozone treated wastewater in all types of activated carbons, followed by ultraviolet disinfected wastewater and coagulated wastewater.Conclusions : It was possible to remove an additional 35-55% of dissolved organic materials upon addition of activated carbon to the treated wastewater although the removal depends on the material of the activated carbon, the injection amount, and the contact time. If an activated carbon process is adopted to the POTW, it can meet the effluent water quality standards (TOC).

Monitoring for freshwater mussel presence in rivers using environmental DNA

AbstractIn 2013, the U.S. Environmental Protection Agency (USEPA) updated its national recommended water quality criteria for the protection of aquatic life from the toxic effects of ammonia in freshwaters. From its updated national dataset, USEPA determined freshwater mussels in the family Unionidae were the most sensitive taxa to ammonia. Thus, it has become necessary to determine whether freshwater mussels exist in waterbodies near discharge locations from Publically Owned Treatment Works (POTWs), to ensure that POTWs are regulated appropriately with regard to ammonia levels in their treated effluent. However, because mussels are notoriously difficult to detect using traditional survey methodologies, most POTWs have not determined whether freshwater mussels exist in their receiving waters. Environmental DNA (eDNA) presents a promising methodology to survey for freshwater mussels in POTW receiving waters. We developed and validated a quantitative polymerase chain reaction (qPCR) assay for the three freshwater mussel taxa that are currently known to exist in California's Central Valley. We then placed a cage with 20 Gonidea angulata into a riverine environment and collected water samples at evenly spaced downstream intervals to determine how habitat type and distance from the caged mussels affected eDNA detection. Using two‐stage occupancy modeling, we determined higher detection probabilities occur in riffle habitats compared to pool or run habitats. We also found surface samples work well for collecting freshwater mussel eDNA in riffle habitats, but are less likely to capture mussel eDNA in pools or runs. The maximum downstream distance at which the eDNA from the 20 placed G. angulata mussels was detected was 8 km. Our study demonstrates that eDNA is a reliable tool for determining freshwater mussel presence in riverine systems, but that sampling should consider habitat type, distance between sampling locations, and time of year for the most effective results.

Rapid Salivary IgG Antibody Screening for Hepatitis A.

Hepatitis A virus (HAV) is a common infection that is transmitted through the fecal-oral route, shed in the stool of infected individuals, and spread either by direct contact or by ingesting contaminated food or water. Each year, approximately 1.4 million acute cases are reported globally with a major risk factor for exposure being low household socioeconomic status. Recent trends show a decrease in anti-HAV antibodies in the general population, with concomitant increases in the numbers of HAV outbreaks. In line with a recreational water study, this effort aims to assess the prevalence of salivary IgG antibodies against HAV and subsequent incident infections (or immunoconversions) in visitors to a tropical beach impacted by a publicly owned treatment works (POTW). We applied a multiplex immunoassay to serially collected saliva samples gathered from study participants who recreated at Boquerón Beach, Puerto Rico. Analysis of assay results revealed an immunoprevalence rate of 16.17% for HAV with 1.43% of the cohort immunoconverting to HAV. Among those who immunoconverted, 10% reported chronic gastrointestinal symptoms and none experienced diarrhea. Tests on water samples indicated good water quality with low levels of fecal indicator bacteria; however, the collection and analysis of saliva samples afforded the ability to detect HAV infections in beachgoers. This rapid assay serves as a cost-effective tool for examining exposure to environmental pathogens and can provide critical information to policy makers, water quality experts, and risk assessment professionals seeking to improve and protect recreational water and public health.

Impact of droughts on industrial emissions into surface waters.

In this paper, we examine the impact of droughts on industrial emissions into surface waters and transfers to publicly owned treatment works (POTWs). We use industrial discharges into surface waters data from the US Environmental Protection Agency's Toxics Release Inventory (TRI) database. We employ runoffs normalized using previous 61-year average runoffs as a proxy for drought. We match both the discharges into surface waters and the runoffs at the 8-digit hydrologic unit code (HUC) level. Our analysis indicates that normalized runoffs of the current and previous years positively influence industrial emissions into surface waters. We also find that the impact of uneven availability of water on emissions is higher on larger facilities. Normalized runoffs of the current and previous years do not have a statistically significant influence on transfers to publicly owned treatment works. However, normalized runoffs of the previous year do affect transfers of larger facilities. Businesses are dependent on water not only for their operations but to discharge their pollutants as well. Climate change will increase the frequency and intensity of droughts and floods. Therefore, every business that requires significant quantities of water must plan to cope with uneven availability of water.

Analysis of factors affecting effluent TOC in publicly owned treatment works

Total organic carbon(TOC) was introduced as the water quality index of the rivers and lakes in 2013. This paper evaluated factors affecting effluent TOC concentrations and treated and discharged loads of existing publicly owned treatment works(POTWs). For selected POTWs with greater treatment capacity than 500㎥/day, factorial analysis was used to consider effects of kinds of biological treatment processes, inflow of other types of wastewater(industrial, livestock, landfill leachate wastewater, etc.) with domestic wastewater, sewer separation rate, and effluent discharging zones in which different effluent criteria applied. As a result, those factors did not show significant effect on effluent TOC concentration of POTWs in effluent discharging zone Ⅰ and Ⅱ. However, In effluent discharging zone Ⅲ and Ⅳ, kinds of biological treatment processes, the inclusion of other waste in influent of domestic wastewater, and the sewer separation rate were significant factors. The treated TOC load in POTWs was also not affected significantly by the variables set in this study. On the other hand, those three factors influenced significantly on the TOC load discharged to water bodies. The sum of factorial effects and the contribution rate of three factors to the discharged TOC load was 60.23 and 41%, 59.57 and 41%, and 42.04 and 18%, respectively.

Adsorption of UV-quenching substances (UVQS) from landfill leachate with activated carbon

Co-treatment of landfill leachate with sewage at publicly owned treatment works (POTWs) is a common leachate management practice. However, the UV absorbing property of UV-quenching substances (UVQS) present in municipal landfill leachate may significantly reduce the efficiency of disinfection at POTWs that adopt ultraviolet irradiation for disinfection. The UVQS represents an emerging concern in the solid waste and wastewater treatment industries. This study aimed to evaluate the performance of activated carbon (AC) for removal of UVQS from landfill leachate in order to address the leachate UV-quenching issue. Results showed that the abatement of leachate UV254 absorbance with AC followed a pseudo-2nd-order reaction or intra-particle diffusion kinetics model. The adsorption isotherm patterns for leachate UV254 absorbance, dissolved organic carbon (DOC), and chemical oxygen demand (COD) well fit the Freundlich models. AC was capable of effectively adsorbing UV-quenching organic matter, regardless of humic acid (HA), fulvic acid (FA), and hydrophilic (HPI) isolates, via both chemisorption and physical adsorption mechanisms. Of note, after the AC adsorption, the residual UV254 absorbance was linearly correlated with COD remaining in leachate and exponentially correlated with residual DOC in leachate, separately. Furthermore, fluorescence excitation-emission matrix (EEM) analyses could indicate the removal of hydrophobic UVQS during AC adsorption, but could not reflect the presence or variation of hydrophilic UVQS. Findings of this study demonstrate that AC adsorption provides an effective treatment option for mitigation of the leachate-induced UV transmittance impacts on POTWs.

Protecting water and wastewater utilities from cyber‐physical threats

AbstractRecent events have highlighted the need to address cybersecurity threats to systems supporting critical infrastructure and federal information systems which are evolving and growing. These threats have become ubiquitous in the United States, and throughout the world. Many information and communications technology (ICT) devices and other components are interdependent so that disruption of one component may have a negative, cascading effect on others. In the United States, the Federal role in cyber‐security has been debated for more than a decade but creating a policy is complicated because in the United States, State and local governments are the major institutions responsible for providing services to their populations. It is important that critical infrastructure such as Publically Owned Treatment Works (POTWs) and Public Water Systems (PWSs) adopt suitable countermeasures to prevent or minimise the consequences of cyber‐attacks. This paper discusses both technological and procedural techniques that can be used to protect against cyber‐threats.

State and green crimes related to water pollution and ecological disorganization: water pollution from publicly owned treatment works (POTW) facilities across US states

Green criminologists often refer to water pollution as an example of a green crime, but have yet to produce much research on this subject. The current article addresses the need for green criminological analyses of water pollution problems, and draws attention to an overlooked issue: water pollution emissions from state owned public water treatment facilities or POTWs. Legally, POTWs may emit certain quantities and kinds of pollutants to waterways following treatment. This does not mean, however, that those emissions have no adverse ecological or public health impacts, or that those emissions cannot also be employed as examples of green crimes or green-state crimes. Indeed, from the perspective of environmental sociology and ecological Marxism, those emissions generate ecological disorganization. Moreover, POTW emissions contain numerous pollutants that generate different forms of ecological disorganization. The current study uses POTW emissions data drawn from the US EPA’s Discharge Monitoring Report system for 2014 to illustrate the extent of pollution emitted by POTWs in and across US states as one dimension of ecological disorganization. To contextualize the meaning of those data, we review US water pollution regulations, review the health and ecological impacts of chemicals emitted by POTWs, and situate those emissions within green criminological discussions of green crime and green-state crimes.

Municipal wastewater sludge as a sustainable bioresource in the United States

Within the United States and Puerto Rico, publicly owned treatment works (POTWs) process 130.5 Gl/d (34.5 Bgal/d) of wastewater, producing sludge as a waste product. Emerging technologies offer novel waste-to-energy pathways through whole sludge conversion into biofuels. Assessing the feasibility, scalability and tradeoffs of various energy conversion pathways is difficult in the absence of highly spatially resolved estimates of sludge production. In this study, average wastewater solids concentrations and removal rates, and site specific daily average influent flow are used to estimate site specific annual sludge production on a dry weight basis for >15,000 POTWs. Current beneficial uses, regional production hotspots and feedstock aggregation potential are also assessed. Analyses indicate 1) POTWs capture 12.56 Tg/y (13.84 MT/y) of dry solids; 2) 50% are not beneficially utilized, and 3) POTWs can support seven regions that aggregate >910 Mg/d (1000 T/d) of sludge within a travel distance of 100 km.

Chemical oxidation for mitigation of UV-quenching substances (UVQS) from municipal landfill leachate: Fenton process versus ozonation

UV-quenching substance (UVQS), as an emerging municipal solid waste (MSW)-derived leachate contaminant, has a potential to interfere with UV disinfection when leachate is disposed of at publicly owned treatment works (POTWs). The objective of this study was to evaluate and compare two chemical oxidation processes under different operational conditions, i.e. Fenton process and ozonation, for alleviation of UV254 absorbance of a biologically pre-treated landfill leachate. Results showed that leachate UV254 absorbance was reduced due to the UVQS decomposition by hydroxyl radicals (·OH) during Fenton treatment, or by ozone (O3) and ·OH during ozonation. Fenton process exhibited a better treatment performance than ozonation under their respective optimal conditions, because ·OH could effectively decompose both hydrophobic and hydrophilic dissolved organic matter (DOM), but O3 tended to selectively oxidize hydrophobic compounds alone. Different analytical techniques, including molecular weight (MW) fractionation, hydrophobic/hydrophilic isolation, UV spectra scanning, parallel factor (PARAFAC) analysis, and fluorescence excitation-emission matrix spectrophotometry, were used to characterize UVQS. After either oxidation treatment, residual UVQS was more hydrophilic with a higher fraction of low MW molecules. It should be noted that the removed UV254 absorbance (ΔUV254) was directly proportional to the removed COD (ΔCOD) for the both treatments (Fenton process: ΔUV254 = 0.011ΔCOD; ozonation: ΔUV254 = 0.016ΔCOD). A greater ΔUV254/ΔCOD was observed for ozonation, suggesting that oxidant was more efficiently utilized during ozonation than in Fenton treatment for mitigation of the UV absorbance.

Nutrient Farming and Traditional Removal: an Economic Comparison

The purpose of this study was to assess the economic feasibility of using large-scale, restored wetlands to assist publicly owned treatment works (POTWs) in meeting the U.S. Environmental Protection Agency's (USEPA) recommended criteria for nutrients, specifically, total nitrogen (2.18 mg/l) and total phosphorous (0.076 mg/l). The assessment compares the cost of nutrient control by advanced wastewater treatment technology to that of wetland treatment technology. The comparison was based on several economic factors: annual operating costs, average costs, marginal costs, and present value.To explore the economic relationship between wastewater and treatment wetlands and to quantify the magnitude of wetland area needed, a case study was developed using the seven water reclamation plants (WRPs) owned and operated by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) and proposed treatment wetlands located adjacent to the Illinois River in the upper Illinois River watershed. Cost functions for both technologies were developed. Using these functions, the economic characteristics of the two technologies were compared assuming, first, that the USEPA's proposed nutrient criteria would be enacted as the enforceable water quality standard by the state regulator, and, second, that a less stringent standard would be established (3.0 mg/l TN and 1.0 mg/l TP). However, the USEPA's phosphorus criterion was modified due to the technical difficulty in achieving an effluent concentration of 0.076 mg/l TP. The more stringent phosphorous criterion was set at 0.5 mg/l TP for this comparison study.The land requirements for a nutrient farm, while extensive, can be easily supplied within the 5,000,000 acres of flood prone land in the Illinois River. However, until large-scale nutrient farms are in existence and greater experience gained in their design and operation, there will be reluctance to use this technology. A series of demonstration projects should be established in various ecoregions to study the design, operation and economic efficiency of treatment wetlands. In addition to greatly improving water quality, nutrient farms can spur recreational development and reduce flood damage.This title belongs to WERF Research Report SeriesISBN: 9781843397335 (Print)ISBN: 9781780404394 (eBook)

Expected versus Actual Outcomes of Environmental Policies: The Clean Water State Revolving Fund

This paper examines the performance of the Clean Water State Revolving Fund (CWSRF), a federally funded program to provide loans to local publically owned treatment works (POTWs) in four states: Iowa, Indiana, Maryland and Texas. We find that between 2007 and 2014, the typical plant receiving a loan in these states substantially improved the quality of effluent discharges of biochemical oxygen demand (BOD) and organic nitrogen (N) in all four states, compared to a sample of plants in the same states that did not receive loans. We also found, however, that plants receiving loans tended to better the performance of plants that did not receive loans in 2007, before the funds were distributed. Thus, while loans were effective in improving water quality, it appeared that the plants receiving loans were not the plants most in need of improvement, but were already among the best. Thus, state authorities responsible for choosing plants receiving loans favored plants with a record of prior success rather than a record of current need.

Riparian plant isotopes reflect anthropogenic nitrogen perturbations: robust patterns across land use gradients

Riparian plants incorporate nitrogen (N) from aquatic, terrestrial, and atmospheric sources, and their stable isotope compositions (δ15N) may reflect land use impacts on N sources and transformations over scales of sites to watersheds. We surveyed leaf δ15N values of 11 common riparian tree, shrub, and herbaceous species from 20 streams and rivers spanning three fifth‐order watersheds in northern Utah, USA (n = 255 sites and 819 leaf samples). Streams spanned undeveloped montane forests to suburban, urban, and agricultural lands. Mean species‐specific differences in leaf δ15N values were relatively small within sites (1.2 ± 2.2‰), although emergent aquatic macrophytes had higher within‐site δ15N values than other growth forms. Leaf δ15N values varied significantly across land‐use categories, and were lowest in undeveloped montane reaches (0.5 ± 1.9‰; mean and standard deviation), intermediate in suburban and urban reaches (2.3 ± 2.6 and 3.2 ± 3.4‰), and greatest in agricultural reaches (4.1 ± 3.1‰). The substantial variation in leaf δ15N values within a land use category often corresponded with local management differences. In an undeveloped montane canyon permitting off‐leash dogs, leaf δ15N values (1.5 ± 1.3‰) exceeded similar canyons that strictly prohibited dogs (δ15N = −0.7 ± 1.1‰). Canyons with cattle grazing had leaf δ15N values enriched by 1.4 and 2.8‰ relative to similar, but un‐grazed canyons. Variation in traffic between 0 and 5000 vehicles per day did not significantly affect leaf δ15N values, although a canyon with 50,000 vehicles per day showed a 5.7‰ increase relative to low‐trafficked canyons. Urban leaf δ15N values were consistently enriched by 2.5 ± 0.6‰ relative to leaves in un‐grazed montane reaches, and leaves in a septic‐impacted suburban reach were enriched by 4.6‰ relative to upstream samples. Samples from a sewage‐impacted urban river averaged 8.0 ± 4.1‰ and reached 22‰ adjacent to publicly owned treatment works (POTW). Another urban river displayed similar values in the absence of POTWs, implicating leaky sewers. Our results demonstrate the capacity of N isotopes from a diverse riparian plant community to inform our spatial understanding of watershed N‐cycling perturbations, and illustrate the impact of human activities on N cycling even within protected watersheds.