The Virginia Department of Environmental Quality (VADEQ) under the direction of the United States Environmental Protection Agency (USEPA) has listed the lower Appomattox River as impaired because it violates current water quality standards for fecal coliforms. To advance the analytical process by which various scenarios for improving water quality within the estuary are examined, an array of computer-based hydrodynamic and water quality models were investigated. The Dynamic Estuary Model (DYNHYD5), developed by USEPA, was used to simulate hydrodynamics within the lower Appomattox River. The Water Quality Analysis Simulation Program (WASP6.1), also developed by USEPA, was employed to perform water quality simulations of fecal coliforms. Also, a detailed literature review examined DYNHYD5 and WASP6.1 model theory, computer-based model solution techniques, and background hydrodynamic theory. DYNHYD5 sensitivity analysis showed that the model was most responsive to tidal heights (seaward boundary conditions) both upstream and downstream within the model network. Specific model parameters were varied during calibration until modeled water surface elevations converged on observed water surface elevations. A goodness-of-fit value of 0.749 was determined with linear regression analysis for model calibration. DYNHYD5 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.829 was calculated. Through sensitivity analysis, WASP6.1 proved to be most responsive to coliform loading rates in the downstream direction and boundary concentrations in the upstream direction. With these results, WASP6.1 input parameters were calibrated against observed fecal coliform concentrations. A goodness-of-fit value of 0.573 was determined with linear regression analysis for model calibration. WASP6.1 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.0002 was calculated. Model results suggest that hydrodynamic model calibration and validation can be improved with additional tidal height observations at the downstream seaward boundary. Similarly, water quality model calibration and validation can possibly be improved with the aid of detailed, time-variable coliform concentrations at the downstream seaward boundary. Therefore, it is recommended that a water quality sampling station and tidal stage recorder be installed at the confluence of the Appomattox and James Rivers to provide for further testing of estuary hydrodynamic and water quality models. / Master of Science

As one of the largest and most productive estuaries in the United States, the Chesapeake Bay is a great economic, ecological, and cultural asset to the Mid-Atlantic region. Excess nitrogen and phosphorus discharge, however, has contributed to reduced levels of dissolved oxygen in various locations throughout the Bay. In 2010, the EPA developed a Total Maximum Daily Load (TMDL) for the entire watershed that established nutrient reduction targets to achieve Bay water quality objectives. The TMDL required states in the Chesapeake Bay watershed to create implementation plans to meet nutrient reductions. Maryland and Virginia specifically established stringent point source regulatory policies designed to meet point source reduction targets. Point source control programs created financial incentives for reducing nutrient discharge beyond regulatory requirements. This thesis will examine the extent to which Maryland and Virginia wastewater treatment plants undertake operational improvements to increase nutrient removal in response to state program incentives. Through quantitative and qualitative analysis, this thesis found evidence of lowered nitrogen discharges in response to financial incentives presented by each states point source control programs at municipal wastewater treatment plants. Maryland achieves modest improvements at a subset of advanced treatment WWTPs as a result of financial incentives presented by the state's public subsidy program. Although Virginia advanced treatment plants operating within a nutrient trading program have little incentive to over-comply, there is some evidence of operational improvements at less advanced nitrogen removal plants / Master of Science

Pathogens are the most common cause of water quality impairment in Virginia. Bacteria TMDLs (Total Maximum Daily Loads) for watersheds are typically created using a modeling approach. These models require characterization of all residential, agricultural, and wildlife sources of bacteria. Wildlife bacteria source characterization is typically conducted with estimates of population and fecal coliform production. A sensitivity analysis was performed on the bacteria TMDL development process and the HSPF (Hydrological Simulation Program-FORTRAN) model to determine how wildlife population and fecal coliform density variability impacts simulated in-stream bacteria loads. The population and fecal coliform density values for seven wildlife species were sequentially varied and run through the TMDL model to analyze the changes in bacteria loads. For population density, high, median, and low values were tested, and for fecal coliform density, high and low values were tested. The analysis was conducted on three watersheds (Abrams Creek, Upper Opequon Creek, and Happy Creek), each with a different dominant land use. The results revealed that all watersheds were sensitive to the high fecal coliform densities of deer, muskrats, and raccoons. However, Happy Creek, the watershed with majority forested land use, was additionally sensitive to the high fecal coliform densities of ducks and the high population density for all species. Using the three watersheds as surrogates for comparing different land uses, the study showed the TMDL modeling process is most sensitive to changes in wildlife in watersheds dominated by forested land use. The results also demonstrated that TMDL calibration is more efficient when adjusting wildlife fecal coliform density rather than population density to match the modeled watershed with the observed water quality data. / Master of Science

Thousands of communities across the nation are exposed to health risks from contaminated drinking water. Upstream anthropogenic land covers have been linked with the degradation of source drinking water quality and likely pose a threat to a community water system's (CWS's) ability to provide safe drinking water. The goal of this study was to predict the differences in compliance with the Safe Drinking Water Act (SDWA) between CWSs based on their upstream land cover, economic situation, and system characteristics. In Central Appalachia, from 2001 to 2016, proportions of land cover in each target CWS's upstream source water watershed were weighted based on their distance to a CWS's source water intake. Violations to the SDWA at respective CWSs over the same period were modeled with their distance weighted land cover proportions, economic status of the county served, and system characteristics as covariates. The major findings were that increases in low intensity development increased the likelihood of a health-based violation, larger CWSs were less likely than smaller CWSs to obtain a monitoring and reporting violation, and CWSs that distributed purchased water were the least likely to incur either violation type. These results suggest that communities that have CWSs that are repeatedly failing to remain in compliance with the SDWA may be able to reduce public health risks associated with drinking water by purchasing from a larger CWS. Further to protect public health, community managers should consider source water protection and/or upgrading a CWS's treatment capacity prior to developing a previously undeveloped area. / Master of Science / Millions of people across the nation face health risks from contaminated drinking water. Understanding what factors influence a community water system's ability to supply safe drinking water is critical in the effort to protect public health. Land cover altered by humans has been found to pollute drinking water sources and may be linked to unsafe drinking water. This study aims to predict the differences in compliance with the Safe Drinking Water Act (SDWA) between community water systems (CWSs) based on their upstream land cover, economic situation, and system characteristics. In Central Appalachia, proportions of land cover between 2001 and 2016 were calculated for each target CWS's upstream source water watershed. Violations to the SDWA were used in a statistical analysis with land cover, economic status of the county served, and system characteristics of respective CWSs. The major findings were that increases in low intensity developed area increased the likelihood of health-based (HB) violations, larger CWSs were more likely than smaller CWSs to monitor and report their water quality, and CWSs that served purchased water were the least likely to have a HB or monitoring and reporting violation. These results suggest that purchasing drinking water from a larger CWS may allow water providers to reduce the risk to public health from unsafe drinking water. Additionally, protecting drinking source water and/or upgrading a CWS's treatment ability prior to developing a previously undeveloped area may reduce threats to drinking water safety.

A water sample concentrator utilizing a membrane adsorption/elutriation procedure for bacterial recovery was developed and field-tested. Influent sample volumes of 19.0 liters were processed by the concentrator within 10 minutes. Standard MPN and membrane filtration tests were conducted to determine the efficiency of the concentrator. In laboratory experiments, an average bacterial recovery of 48 percent was accomplished when E. Coli was the bacterium concentrated. An average recovery of 78 percent was achieved with Streptococcus faecalis. Various commercially available 142 mm diameter membrane filters were tested with the concentrator. Millipore membrane filters having a porosity of 0.45 m were found to be superior to Cox membrane filters with 0.45 and 5.0 m porosities and to zeta plus filters. The most promising technique for eluting bacteria from the membrane filter appeared to consist of mixing the filter and 125 mL of three percent bovine serum solution at pH 9.0 in an electric blender for 30 seconds and then allowing 15 minutes of contact. Miscellaneous experiments investigated the addition of multivalent cations to enhance adsorption of bacteria to the membrane filters, the use of vacuum induced flow through the concentrator and the possibility of monitoring bacterial levels through adenosine triphosphate analysis. In the field trials, the water sample concentrator detected coliform bacteria in drinking water in which no coliforms were detected in grab samples by the standard MPN method. / Master of Science

Livestock best management practices (BMPs) such as streamside exclusion fencing are installed to reduce cattle impacts on stream water quality such as increases in bacteria through direct deposition and sediment through trampling. The main objective of this study is to assess the effects of different cattle management strategies on water quality. The project site was located near Keezletown, VA encompassing Cub Run and Mountain Valley Road Tributary streams. During two, one-week studies, eight automatic water samplers took two-hour composites for three periods: baseline, cattle access, and recovery. During the cattle access period, livestock were able to enter the riparian zone normally fenced off. Water samples were analyzed for E.coli, sediment, and nutrients to understand the short-term, high-density, or flash grazing, impact on water quality. Additional weekly grab and storm samples were collected. Results show that cattle do not have significant influence on pollutant concentrations except in stream locations where cattle gathered for an extensive period of time. Approximately three cattle in the stream created an increase in turbidity above baseline concentrations. E.coli and TSS concentrations of the impacted sites returned to baseline within approximately 6 to 20 hours of peak concentrations. Weekly samples show that flash grazing does not have a significant influence on pollutant concentrations over a two-year time frame. Sediment loads from storms and a flash grazing event showed similar patterns. Pollutant concentrations through the permanent exclusion fencing reach tended to decrease for weekly and flash grazing samples. / Master of Science

Nine recirculating systems at the Virginia Tech Aquaculture Center were placed on line and stocked with yellow perch, <I>Perca flavescens</I>, fingerlings. Fish were stocked at a density of approximately 455 fish m³. Biofilter types were the only factor differing among system designs and were an upflow pulsed bed bead filter, packed tower trickling filter and a rotating biological contactor (RBC). After stocking, systems were allowed to acclimate using ammonia excreted by the yellow perch. Following acclimation, a comparative analysis on biofilter performance began. To evaluate filter performance, water quality parameters tested were temperature (°C), pH, dissolved oxygen (DO), total ammonia-nitrogen (TAN), nitrite-nitrogen (NO₂⁻-N), nitrate-nitrogen (NO₃⁻-N), alkalinity (as CaCO₃), water hardness (as CaCO₃), carbonaceous biochemical oxygen demand (cBOD₃), dissolved organic carbon (DOC), and total suspended solids (TSS). Basic water quality analysis encompassed samples drawn at 8 AM. TAN mass removal analysis encompassed water quality samples drawn at 8 AM and over 24 hours. Higher TAN mass removal rates were achieved in trickling and RBC filters than in bead filters for 8 AM (0.037, 0.14, and 0.004 g/m²/d, respectively) and diurnal sample periods. Analysis of areas under mass removal curves depicted RBC filters as surface area limited. Trickling filters proved most effective at carbon dioxide stripping and pH maintenance and also effectively removed TSS from the culture water. The study did not show filter type as having a significant effect on median organic water quality parameter values. / Master of Science

Hedonic models are used to estimate implicit prices for water quality in housing markets. Recent studies aggregate sales across large spatial areas in scaled-up models leading to a concern that these models may overlook regional heterogeneity in water-quality preferences. We estimate scaled-up hedonic models comprised of multiple states and individual states and investigate how observations from subregions can differ. We find that the scaled-up model results are driven by select subregions. The results of this study call into question hedonic models using data for large geographic regions where substantial differences may arise across housing markets. / M.S. / Water quality in lakes impacts the prices people pay for lakefront properties. However, these effects can vary across different housing markets. We study whether owners of lakefront properties throughout the northeast and upper Midwest are willing to pay the same amount for water in lakes. We find that in multi-state housing markets, the effects from one state can dominate the overall results and there is likely heterogeneity in preferences across housing markets.

The purpose of this problem was to determine the cause of tastes and odors in the Breckenridge water supply and to isolate and culture the organisms responsible for the offensive chemicals.

This dissertation is comprised of three essays examining methods for surface water quality valuation. The first essay uses Zillow's ZTRAX property transaction database to investigate variation in hedonic price effects of water clarity on single-family houses throughout the United States. I consider five spatial scales and estimate models using different sample selection criteria and model specifications. The results indicate considerable spatial heterogeneity both within and across the four U.S. Census regions. However, I also find heterogeneity resulting from different types of investigator decisions, including sample selection and modelling choices. Thus, it is necessary to use practical knowledge to consider the limits of market areas and to investigate the robustness of estimation results to investigator choices. In the second essay, I integrate a coastal recreation demand model for Southern New England with property sales in Massachusetts and Rhode Island to estimate the impacts of water quality improvements for freshwater and saltwater resources throughout the region. While traditional hedonic studies for water quality reveal the direct effects of local water quality on housing prices, the spatial extent of the models is limited to 2 km from the waterfront. Integrating recreation demand models with hedonic models allows identification of additional indirect effects of water quality at recreation sites that are capitalized in housing markets through a recreational index (i.e., the potential recreational benefits for a neighborhood). However, the spatial extent of these models is currently untested. I compare the spatial extent of indirect and direct effects of water quality for multiple water quality inputs isolating spatial and temporal sources of variation. The results indicate heterogeneity in the direct effects of freshwater and saltwater clarity depending on whether the source of variation is spatial or temporal. Conflating spatial and temporal water quality variation can lead to anomalous conclusions on the impacts of coastal recreation on housing markets. In the third essay, I evaluate meta-regression models (MRMs) that are used by policy makers in calculating the potential benefits of improvements in environmental quality resulting from proposed regulatory actions. MRMs lay the foundation for benefit transfers applied by EPA to recent rulemakings under the Clean Water Act (CWA) in addition to other environmental contexts (e.g., health benefits under the Clean Air Act). While recent literature has emphasized the necessity that MRMs satisfy key theoretical conditions, including scope sensitivity and the adding up condition, existing MRMs that fulfil these properties require imposing structural model restrictions or removing relevant explanatory variables from the MRM at the expense of model fit and predictive performance. This study presents a method for defining MRMs that draws on characteristics of the given benefits transfer scenario and its relationship to the metadata while satisfying the adding up condition. This modelling framework outperforms the model used by EPA in model fit and predictive performance. Applying the results to a recent CWA rule, I find the model used by EPA substantially underestimates the potential benefits. / Doctor of Philosophy / This dissertation is comprised of three essays examining methods for surface water quality valuation. The first essay uses property sale models to evaluate spatial differences in the impacts of lake water quality on housing markets throughout the United States. I evaluate how investigator decisions related to spatial scale of the model, sample selection criteria, and model specification effects the observed results. I find variation in the impacts of water on property sale prices across the nation. However, the results in some regions are highly sensitive to investigator decisions, implying limitations to using a single model to represent the impacts. The second essay integrates a property sale model for water quality with a model that examines willingness to pay for coastal recreation in Southern New England. I evaluate the impacts of water quality at coastal recreation sites on property sales in Massachusetts and Rhode Island and compare the results to the impacts of local water quality. I find the effects of local water quality is largest on the coast but only capitalized into property sales up to 2 km from the waterfront. I do not find expected results for coastal recreation. The third essay evaluates the models used by policy makers to calculate the potential benefits of improvements in water quality resulting from regulatory action. Previous models prioritized theoretical properties of models, such as the adding up condition, at the expense of model fit and predictive performance. I develop a hybrid model approach that can be used model water quality benefits while satisfying the adding up condition with improved model performance. I apply the model to a recently proposed rulemaking and find the benefits potential benefits greatly exceed those presented in the rule making.