Nonpoint source pollution from cropland has been identified as the primary source of nitrogen and sediment, and a significant source of phosphorus in the Chesapeake Bay. These pollutants, whether from point or nonpoint sources, have been found to be the primary cause of declining water quality in the Bay. Numerous studies have indicated that, for many watersheds, a few critical areas are responsible for a disproportionate amount of the nutrient and sediment yield. Consequently, if pollution control activities are concentrated in these critical areas, then a far greater improvement in downstream water quality can be expected with limited funds. In this research a nitrogen transport model is incorporated into ANSWERS, a distributed parameter watershed model. The nitrogen model simulates nitrogen transformations of applied fertilizer and soil nitrogen in the soil. Dissolved nitrogen transport in surface runoff is modeled by assuming complete mixing of the soil surface layer and surface runoff. Sediment-bound nitrogen transport is modeled as a function of the clay content of transported sediment. The extended ANSWERS model was verified using water quality data from rainfall simulator plot studies conducted on the Prices Fork Research Farm in Blacksburg, Virginia. The four plots were 5.5 m wide by 18.3 m long with average slopes ranging from 6.2 to 11 percent. Two of the plots were tilled conventionally, and two were no-till. Simulated rainfall at an intensity of 5 cmlh was applied to the plots and runoff samples were analyzed for sediment and nitrogen. The model was then verified by comparing the simulated response with the observed data. The model predicted sediment-bound nitrogen losses within a factor of two. The model tended to overpredict dissolved nitrogen losses by a factor of five. The model shows potential as a best management practice planning tool, however, further verification of model predictions versus observed data is required. / Master of Science

This study compared physical characteristics used when selecting comparison (healthy) watersheds for the All-Forested Load Multiplier (AllForX) Approach, and examined a quantitative watershed characteristic as a selection criterion. The AllForX Approach uses a regression relationship between Virginia Stream Condition Index (VSCI) scores and AllForX values (a unit-less multiplier that is the ratio of a modeled existing sediment load divided by a modeled all-forested load condition) for an impaired watershed and several comparison watersheds to develop sediment TMDL target loads. The Generalized Watershed Loading Function (GWLF) model was used to simulate sediment loads for 20 watersheds (four impaired and 16 comparison) in the Upper James and New River basins in Virginia's Ridge and Valley physiographic region. Results suggest that within Virginia's Ridge and Valley physiographic region it may be possible to select comparison watersheds that are of a different stream order (watershed size) and lie in different river basins from the impaired watershed. Results further indicated that the topographic index (TI) distributions were not different across the modeled watersheds, indicating the watersheds are hydrologically similar. These results support selecting comparison watersheds regardless of river basin or stream order within Virginia's Ridge and Valley physiographic region. Finally, there was no statistical difference between the AllForX regressions when using the entire period of record or the two most recent VSCI data points. Therefore, for the watersheds modeled for this study, either all of the VSCI samples or the two most recent may be used in the AllForX Approach. / Master of Science

The first civilizations we have ever heard of were along the banks of mighty rivers like Nile, Euphrates, Indus and Huang. These civilizations developed along rivers as riverfronts provided opportunities for tradeand transportation, fertile land to grow crops, water for drinking, washing, livestock and other domestic uses and food in the form of fish. Gradually, they came to define cities, became a part of identities of people, such as "India" from "Indus," while, providing a sense of place and connecting the populace to nature. Yet rivers have often ended up being abused and neglected in our course towards urbanization. It is this "neglect" that needs to be shunned. The relationship with the rivers needs to be re-forged. To develop a strategy for this shift in attitude, this research has chosen the case of Chesapeake Bay. Chesapeake Bay is an estuary lying inland from the Atlantic Ocean. It has mainland North America to its west and Delmarva Peninsula on the east. It is the largest Estuary in the United States. More than 150 major rivers and streams flow into the Chesapeake Bay. The estuary provides habitat to several species of wildlife and aquatic life. Today, this bay faces many issues such as nutrient and sediment pollution, Storm water runoff, lowering of shellfish species etc. One of the major causes of the polluted bay is storm water runoff. Storm water washes pollution off the roads and other surfaces and takes them to the water. Stormwater is generally more polluted in urban areas than rural areas. This thesis, attempts to demonstrate what can be done with a typical pixel in the whole mosaic of the bay . The Maine Avenue Fish Market, sitting just upstream to the now being developed Southwest Waterfront, seems a perfect choice for this endeavor. This market, a small urban waterfront space, is ideal for exploring ideas and solutions to avoid water pollution by stormwater, cleaning the quality of water and also, in the process, develop the area in relation to the city and its surroundings. This thesis aims to establish an ecological and social relationship between the natural resource and the urban life. / Master of Science

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