Browsing by Author "Yagow, Eugene R."

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    Advances in Watershed Management: Modeling, Monitoring, and Assessment
    Benham, Brian L.; Yagow, Eugene R.; Chaubey, I.; Douglas-Mankin, K. R. (American Society of Agricultural and Biological Engineers, 2011)
    This article introduces a special collection of nine articles that address a wide range of topics all related to improving the application of watershed management planning. The articles are grouped into two broadly defined categories.. modeling applications, and monitoring and assessment. The modeling application articles focus on one of two widely used watershed-scale water quality modeling packages: HSPF or SWAT The HSPF article assesses the model's robustness when applied to watersheds across a range of topographic settings and climatic conditions. In the SWAT-related articles, researchers used the model to inform watershed management efforts in a variety of ways, including subwatershed prioritization in the context of achieving broader watershed management goals, examining the utility of applying SWAT in a watershed receiving groundwater inputs from outside the topographic watershed boundaries, and estimating the uncertainty and risk associated with meeting TMDL target loads. The monitoring and assessment articles cover such diverse topics as an examination of how best management practice effectiveness is assessed, examination of estimated nutrient loads to a reservoir where a nutrient TMDL has been developed, examination of the sources of fecal indicator bacteria in an urban watershed, and detailed accounting of issues related to flow measurements in small watersheds. The articles in this collection contribute to the body of literature that seeks to inform and advance sound watershed management planning and execution.
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    Agricultural best management practices and water quality in the Bush River watershed, Virginia
    Smolen, M. D.; Yagow, Eugene R.; Younos, Tamim M. (Virginia Agricultural Experiment Station, 1984-07)
    This project was developed as part of the implementation phase of the PL 92-500 Section 208 Program for control of nonpoint pollution from agricultural sources. The project objective was to determine the effect of Best Management Practices on sediment and nutrient yields in agricultural watersheds. The research consisted of field monitoring at two small watershed sites in the Bush River basin, near Farmville, Virginia. One watershed used Best Management Practices (BMP Watershed) consisting of contour strip cropping in combination with crop rotation and sod waterways. The second watershed, with conventional management ( CONV Watershed), was approximately half agricultural and half forested. Concurrent with the small watershed monitoring study, a weekly sampling program was maintained to evaluate the ambient water quality on the main tributary system of the Bush River. The results of the study include the first field-based quantification of sediment yield and delivery ratios in this area. Although the results of this study are not conclusive, the agricultural watershed with recommended Best Management Practices tended to produce reduced levels of gross erosion, runoff, and sediment and nutrient yields. Sediment delivery ratios were compared with several alternative estimation techniques. Particle size distributions, nutrient enrichment ratios and sediment delivery ratios estimated in this study may be useful in computing nonpoint pollution effects of agricultural land use in the Southeastern Piedmont of the United States. The ambient data developed in this study may be useful in the future to estimate the effect of a planned PL-566 Conservation Plan that is being implemented on the Bush River watershed.
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    Assessing the effects of cattle exclusion practices on water quality in headwater streams in the Shenandoah Valley, Virginia
    Maschke, Nancy Jane (Virginia Tech, 2012-01-27)
    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.
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    Auxiliary Procedures for the AGNPS Model in Urban Fringe Watersheds
    Yagow, Eugene R. (Virginia Tech, 1997-02-28)
    The Agricultural Nonpoint Source model (AGNPS) is a single-event grid-based model used for simulating runoff, sediment and nutrients from agricultural areas. This study involved using geographic information system (GIS) spatial data and functionality to improve the spatial and temporal assignment of parameter values for the AGNPS 5.0 model and incorporated methods for representing urban fringe land uses and their nonpoint source (NPS) pollution contributions in model inputs. Auxiliary procedures for modeling with AGNPS were developed both for enhancing input into the model and for enhancing modeled output. On an event basis, one procedure automated the creation of complex-formatted AGNPS 5.0 model input files using GIS as a spatial data manager. One pair of alternative procedures were developed to automate the assignment of parameter values on an event basis. One procedure used typical average annual parameter values, and the second assigned parameter values using adaptations of existing time-dependent relationships. On a monthly basis, a sequencing procedure was created to perform multiple runs with the model for a list of storms while updating parameters for each event and aggregating monthly modeled spatial output. Another pair of alternative procedures were developed to facilitate the simulation of monthly output from AGNPS modeled events. The first of these aggregated event output for all storms in each month, while the second supplemented the aggregated output with baseflow and septic system loads. The study area was the 6,500 ha urbanizing Bull Run watershed in northern Virginia, which was modeled as 14,621 cells. Databases were assembled and 109 selected storm events within a 16-year period were modeled using the above procedures. Event data were added together, where necessary, to correspond with observed data from composite-sampled intervals. Output from the two event parameterization procedures were compared with monitored loads calculated for 89 composite periods, while output from the two monthly simulation procedures were compared with monthly monitored data for 23 complete months. The monitored-modeled comparisons were considered inconclusive. Evidence strongly suggested that the rainfall records from a rain gauge outside the watershed did not correspond well with monitored runoff. The average runoff produced with the AGNPS model from the 109 selected storms amounted to 40.7% of rainfall, consistent with the calculated long-term average of 38% for the Bull Run watershed. A nonpoint source pollution index was developed to utilize monthly modeled total nitrogen, total phosphorus, and suspended sediment. Individual rating curves were developed to separately transform loads and concentrations of each pollutant into sub-index values. The maximum sub-index from each parameter was added together and averaged for the index. The index was calculated at the watershed outlet from monitored data, and in a spatially-distributed fashion along all streams from simulated output.
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    Biotic and Abiotic Remediation of Acetaminophen with Woodchip and Biochar-amended Woodchip Adsorbents
    Wade, James Patrick (Virginia Tech, 2015-11-13)
    Pharmaceuticals and personal care products found in the environment pose a significant hazard to human and ecosystem health. While there has been significant work on the fate and remediation of pharmaceuticals and personal care products in wastewater treatment, relatively little work has explored the fate, transport and remediation of these compounds in non-point source input. This is concerning given the increasing use of pharmaceuticals in livestock production and wastewater treatment derived biosolids frequently applied to land. These experiments aimed to quantify the abiotic adsorption and biotic transformation and uptake potential of woodchips and biochar-amended woodchips as a potential sorbent strategy for diffuse acetaminophen (ACT) pollution. Batch reactions were created in triplicate, supplied with 5 mM ACT, and analyzed over an eight hr period using ultraviolet spectrophotometry (298 nm). Ultraviolet absorbance readings for each time step then were compared to standard curves and solution ACT concentration was determined. Decreases in ACT from initial concentrations were the result of either abiotic and/or biotic. Overall, the woodchips and biochar-amended woodchips showed similar removal efficiency (16-21% of initial concentration). Whole model ANOVA analysis showed biologic activity having no significant effect on ACT solution concentration. However, within group ANOVA comparison showed significant differences between abiotic and biotic WC and abiotic and biotic WC treatments (controlling for media). Thus, the media effect could have masked the effect of biology on ACT removal. Species capable of degrading ACT exist and further study into their ability to grow and survive on these sorbents requires further work.
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    Changes in landuse patterns in upland watersheds of Eastern Luangwa Valley, Zambia, and the potential impact on runoff and erosion
    Nyirongo, Victor Wilford Kayiwaze (Virginia Tech, 2009-08-12)
    Four small watersheds, Kamwamphula, Luelo, Kanyanga and Mphiri, near Emusa (Lundazi District) in Eastern Province, Zambia, were studied to document transitions in land use over time and to project the impacts of land use and topography on runoff, erosion and sediment delivery. Landuse was delineated from 2007 IKONOS image (one meter pixel), and Landsat imagery was used to depict the historic changes in landuse between the period of 1989 and 2007. The GWLF model was used to predict the impact of the landuses on the hydrology of the area. There had been an increase in clearing of forest area mainly due to the expansion of cropland area. The highest rate of clearing was predicted for the Kamwamphula watershed where the forest cover decreased from 95% to 71% over the 18 year period. The GWLF model was used to predict the impact of the landuse on the hydrology and sediment delivery. In comparison with the limited field data available from the four watersheds, the GWLF model gave poor prediction of streamflow, probably because the hydrology of the area is poorly understood and dambo function in the landscape is not well represented in the model. Highest runoff, erosion and sediment yields came from Luelo watershed which has steeper slopes and, less vegetative cover and poor permeability of soils. The GWLF gave poor prediction of streamflow, probably, because the hydrology of the area is poorly understood.
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    Comparing Alternative Methods of Simulating Bacteria Concentrations with HSPF Under Low-Flow Conditions
    Hall, Kyle M. (Virginia Tech, 2007-09-03)
    During periods of reduced precipitation, flow in low-order, upland streams may be reduced and may stop completely. Under these "low flow" conditions, fecal bacteria directly deposited in the stream dominate in-stream bacteria loads. When developing a Total Maximum Daily Load (TMDL) to address a bacterial impairment in an upland, rural watershed, direct deposit (DD) fecal bacteria sources (livestock and wildlife defecating directly in the stream) often drive the source-load reductions required to meet water quality criteria. Due to limitations in the application of existing watershed-scale water quality models, under low-flow conditions the models can predict unrealistically high in-stream fecal bacteria concentrations. These unrealistically high simulated concentrations result in TMDL bacteria source reductions that are much more severe than what actually may be needed to meet applicable water quality criteria. This study used the Hydrological Simulation Program-FORTRAN (HSPF) to compare three low-flow DD simulation approaches and combinations (treatments) on two Virginia watersheds where bacterial impairment TMDLs had been previously developed and where low-flow conditions had been encountered. The three methods; Flow Stagnation (FS), DD Stage Cut-off (SC), and Stream Reach Surface Area (SA), have all been used previously to develop TMDLs. A modified version of the Climate Generation (CLIGEN) program was used to stochastically generate climate inputs for multiple model simulations. Violations of Virginia's interim fecal coliform criteria and the maximum simulated in-stream fecal coliform concentration were used to compare each treatment using ANOVA and Kruskal Wallis rank sum procedures. Livestock DD bacteria sources were incrementally reduced (100%, 50%, 15%, 10%, 5%) to represent TMDL load reduction allocation scenarios (allocation levels). Results from the first watershed indicate that the FS method simulated significantly lower instantaneous criterion violation rates at all allocation levels than the Control. The SC method reduced the livestock DD load compared to the Control, but produced significantly lower instantaneous criterion violation rates only at the 100% allocation level. The SA method did not produce significantly different instantaneous criterion violation rates compared to the Control. Geometric mean criterion violation rates were not significantly different from the Control at any allocation level. The distributions of maximum in-stream fecal coliform concentrations simulated by the combinations SC + FS and SC + SA + FS were both significantly different from the Control at the 100% allocation level. The second watershed did not produce low-flow conditions sufficient to engage the FS or SC methods. However, the SA method produced significantly different instantaneous violation rates than the Control at all allocation levels, which suggests that the SA method continues to affect livestock DD loads when low-flow conditions are not simulated in the watershed. No significant differences were found in the geometric mean violation rate or distribution of maximum simulated in-stream fecal coliform concentrations compared to the Control at any allocation level. This research suggests that a combination of the SC and FS methods may be the most appropriate treatment for addressing unrealistically high concentrations simulated during low-flow conditions. However, this combination must be used with caution as the FS method may increase the maximum simulated in-stream fecal coliform concentration if HSPF simulates zero volume within the reach.
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    Comparing Two Methods for Developing Local Sediment TMDLs to Address Benthic Impairments
    Wallace, Carlington W. (Virginia Tech, 2012-04-23)
    Excessive sedimentation is a leading cause of aquatic life use impairments in Virginia. As required by the Clean Water Act, a total maximum daily load (TMDL) must be developed for impaired waters. When developing a TMDL for aquatic life use impairment where sediment has been identified as the primary pollutant, the target sediment load is often determined using a non-impaired reference watershed, i.e., the reference watershed approach (RWA). The RWA has historically been used in Virginia to establish TMDL target sediment loads because there is no numeric ambient water quality criterion for sediment. The difference between the sediment load generated by the reference watershed and the load generated by the impaired watershed is used to determine the sediment load reduction required to meet the TMDL target load in the impaired watershed. Recent quantification of the Chesapeake Bay TMDL based on Phase 5.3 of the Chesapeake Bay Watershed Model (CBWM) offers a simpler and potentially more consistent method of calculating target sediment loads for impaired watersheds within the Chesapeake Bay watershed. Researchers in the Biological Systems Engineering department at Virginia Tech have developed the "disaggregate method" (DM) which uses landuse inputs to, and pollutant load outputs from, the CBWM to determine pollutant load reductions needed in watersheds whose areas are smaller than the smallest modeling segments generally used in the CBWM. The DM uses landuse-specific unit area loads from two CBWM model runs (an existing condition run and TMDL target load run) and a finer-scale, locally assessed landuse inventory to determine sediment loads. The DM is simpler and potential more consistent than the reference watershed approach. This study compared the reference watershed approach and the disaggregate method in terms of required sediment load reduction. Three sediment-impaired watersheds (Long Meadow Run, Taylor Creek and Turley Creek) within the Chesapeake Bay watershed were used for the study. Study results showed that the TMDL development method used to determine sediment loads would have noticeable effects on resulting sediment-load reduction requirements. For Taylor Creek, the RWA required 20.4 times greater reductions in sediment load (tons/yr) when compared to the DM. The RWA also required 9.2 and 10.4 times greater reductions for Turley Creek and Long Meadow Run watersheds, respectively. On a percentage basis, the RWA for reduction Taylor Creek was 7.3 times greater than that called for by the DM. The RWA called for 4.4 and 4.6 times greater percent reductions for Turley Creek and Long Meadow Run watersheds, respectively. An ancillary objective of this research was to compare the sediment load reductions required for the impaired and their respective RWA-reference watersheds, using the DM. This comparison revealed that, both Taylor Creek and Turley Creek watersheds required less sediment load reduction than their respective reference watersheds, while the load reductions required for Long Meadow Run were slightly greater than its reference watershed. There are several issues associated with either the RWA or the DM for developing sediment TMDLs. Those issues are discussed in detail. Recommendations the need for further studies, based in questions raised by the research presented here are also discussed.
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    Comparison of Two Alternative Methods for Developing TMDLs to Address Sediment Impairments
    Wallace, Carlington W.; Benham, Brian L.; Yagow, Eugene R.; Gallagher, Daniel L. (2018-12)
    While excessive sediment is a leading cause of aquatic life use impairments in free-flowing rivers in Virginia, there is no numeric sediment-water quality criterion. As a result, total maximum daily load (TMDL) sediment loads are often established using a comparable, nonimpaired reference watershed. Selecting a suitable reference watershed can be problematic. This case study compared the reference watershed approach (RWA) which uses the Generalized Watershed Loading Function and the disaggregate method (DM) which uses output from Phase 5.3 of the Chesapeake Bay Watershed Model. In this case study, the two methods were used to develop sediment TMDLs for three impaired watersheds in Virginia (Taylor Creek, Turley Creek, and Long Meadow Run). In this case study comparison, the RWA required between 12.8 and 14.7 times greater sediment load reductions (t/year) to reach the TMDL load (Taylor Creek > Long Meadow Run > Turley Creek) when compared to the reductions called for using the DM. While each TMDL development method has inherent limitations, the DM uses output from the Chesapeake Bay Watershed Model to establish TMDL target loads. This means that the application of the DM is restricted to the Chesapeake Bay Watershed.
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    Comparison Watershed Selection When Applying the AllForX Approach for Sediment TMDL Development
    Bronnenkant, Kristine Nicole (Virginia Tech, 2014-04-15)
    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.
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    December 2006 Report Of The Academic Advisory Committee To Virginia Department Of Environmental Quality: Freshwater Nutrient Criteria For Rivers And Streams
    Zipper, Carl E.; Yagow, Eugene R.; Walker, Jane L.; Smith, Eric P.; Shabman, Leonard A.; Smock, Leonard A.; Hershner, Carl H.; Younos, Tamim M.; Benfield, Ernest F.; Bukaveckas, Paul A.; Garman, Greg C.; Kator, Howard I.; Lung, Wu-Seng; Stephenson, Stephen Kurt (Virginia Water Resources Research Center, 2007-01-10)
    This report reviews activities conducted by the Academic Advisory Committee to the Virginia Department of Environmental Quality (DEQ) between July and December 2006. Activities were conducted for the purpose of developing recommendations for DEQ regarding nutrient criteria for freshwater rivers and streams.
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    December 2006 Report of the Academic Advisory Committee to Virginia Department of Environmental Quality: Freshwater Nutrient Criteria for Rivers and Streams
    Zipper, Carl E.; Yagow, Eugene R.; Walker, Jane L.; Smith, Eric P.; Shabman, Leonard A.; Smock, Leonard A.; Hershner, Carl H.; Younos, Tamim M.; Benfield, Ernest F.; Bukaveckas, Paul A.; Garman, Greg C.; Kator, Howard I.; Lung, Wu-Seng; Stephenson, Stephen Kurt (Virginia Water Resources Research Center, 2007-01-10)
    This report reviews activities conducted by the Academic Advisory Committee to the Virginia Department of Environmental Quality (DEQ) between July and December 2006. Activities were conducted for the purpose of developing recommendations for DEQ regarding nutrient criteria for freshwater rivers and streams.
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    Effect of Golf Course Turfgrass Management on Water Quality of Non-tidal Streams in the Chesapeake Bay Watershed
    Wilson, Chantel (Virginia Tech, 2015-04-09)
    Turfgrass management activities on golf courses have been identified as a possible source of Chesapeake Bay nutrient pollution. Total Maximum Daily Load goals are in place to reduce nutrient amounts entering the Bay. Dissertation investigations include (1) the role of golf course turfgrass management in nutrient deposition or attenuation in local streams, (2) estimations of total nitrogen (N) discharging to the watershed from stream outlet points as a function of land use and watershed area, and (3) other factors potentially affecting water quality on golf courses, including soil characteristics and use of best management practices (BMPs). Total N, nitrate-N, ammonium-N, phosphate-phosphorus (P), streamwater temperature, specific conductance (SpC), pH and dissolved oxygen (DO) were sampled at 12-14 golf course stream sites in the James River and Roanoke River watersheds during baseflow conditions. Discharge was determined at outflow locations. Unit-area loads (UALs) were calculated from monitoring data. These UALs were then compared to UALs from Chesapeake Bay Watershed Model land use acreages and simulated loads for corresponding watershed segments. Virginia golf course superintendents were also surveyed to determine BMP use. No consistent impairment trends were detected for streamwater temperature, SpC, pH, or DO at any of the sites. Outflow NO3-N was below the 10 mg L-1 EPA drinking water standard. However, some sites may be at increased risk for benthic impairment with total N concentrations >2 mg L-1, as suggested by VADEQ. Significant increases in nitrate-N at OUT locations were measured at four sites, whereas decreases were measured at two sites. Ammonium-N significantly decreased at two sites. Golf course N UALs calculated from baseflow monitoring were lower than or similar to UALs estimated for forested areas in the associated watershed segment at seven out of the 12 sites. Golf course UALs ranged from 1.3-87 kg N ha-1 yr-1. Twenty-one of 32 surveyed BMPs had an adoption rate ≥50% among survey respondents. In most cases, presence of golf courses generally does not appear to significantly degrade baseflow water quality of streams in this study. Management level appears to be an influencing factor on water quality and concerns may be heightened in urban areas.
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    An Examination of the Reference Watershed Approach for TMDLs with Benthic Impairments
    Wagner, Rachel Cain (Virginia Tech, 2004-04-22)
    This research addresses the Reference Watershed Approach (RWA) in the TMDL process for benthic impairments. In the RWA, do different land use sources (DOQQ and NLCD) or use of alternative water quality models (GWLF and SWAT) result in different stressor loadings? Is there a difference in stressor loadings when different reference watersheds are used? Study results showed that using different land use sources resulted in required stressor reductions that were different by greater than 10%. In one scenario, use of the NLCD-based land use parameters results in 3.5 times greater reductions than use of DOQQ-based land use parameters. With respect to water quality model selection, in two of the three scenarios considered, a difference in stressor reduction requirements of greater than 10% resulted from using different models. Differences in load reduction requirements are also seen when different reference watersheds are used, regardless of the water quality model or the land use source used. Different references result in a difference of as much as 73% in required sediment reductions in the impaired watershed: the required reductions using one reference watershed are 6.2 times as great as when another is used. Possible alternatives to the RWA include water quality standards to set the target level for many of the common stressors on the benthic assemblage, regression equations that relate benthic stressors to the RBP II score, or averaging of stressor reduction requirements obtained from using the Reference Watershed Approach on several different reference watersheds.
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    Issues Related to Freshwater Nutrient Criteria for Lakes and Reservoirs in Virginia
    Zipper, Carl E.; Ney, John J.; Smock, Leonard A.; Smith, Eric P.; Little, John C.; Stephenson, Stephen Kurt; Bukaveckas, Paul A.; Yagow, Eugene R.; Walker, Jane L.; Younos, Tamim M. (Virginia Water Resources Research Center, 2005-04)
    This report of the Academic Advisory Committee (AAC) to the Virginia Department of Environmental Quality (DEQ) contains information intended to aid DEQ’s development of nutrient criteria for the state of Virginia in a manner which is compliant with EPA requirements. This report builds upon an earlier report prepared by the AAC in July of 2004 (AAC 2004), which contains background and justification for the procedures employed. The report addresses issues related to freshwater nutrient criteria development for lakes and reservoirs. It includes six appendices: a summary of lake data used in this report (Appendix A), a paper comparing two reservoirs in Virginia (Appendix B), responses to DEQ questions concerning dissolved oxygen criteria for lakes (Appendix C), and lake recreational user perception (Appendices D).
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    Model-based Tests for Standards Evaluation and Biological Assessments
    Li, Zhengrong (Virginia Tech, 2006-08-15)
    Implementation of the Clean Water Act requires agencies to monitor aquatic sites on a regular basis and evaluate the quality of these sites. Sites are evaluated individually even though there may be numerous sites within a watershed. In some cases, sampling frequency is inadequate and the evaluation of site quality may have low reliability. This dissertation evaluates testing procedures for determination of site quality based on modelbased procedures that allow for other sites to contribute information to the data from the test site. Test procedures are described for situations that involve multiple measurements from sites within a region and single measurements when stressor information is available or when covariates are used to account for individual site differences. Tests based on analysis of variance methods are described for fixed effects and random effects models. The proposed model-based tests compare limits (tolerance limits or prediction limits) for the data with the known standard. When the sample size for the test site is small, using model-based tests improves the detection of impaired sites. The effects of sample size, heterogeneity of variance, and similarity between sites are discussed. Reference-based standards and corresponding evaluation of site quality are also considered. Regression-based tests provide methods for incorporating information from other sites when there is information on stressors or covariates. Extension of some of the methods to multivariate biological observations and stressors is also discussed. Redundancy analysis is used as a graphical method for describing the relationship between biological metrics and stressors. A clustering method for finding stressor-response relationships is presented and illustrated using data from the Mid-Atlantic Highlands. Multivariate elliptical and univariate regions for assessment of site quality are discussed.
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    Release and Transport of Bacteria and Nutrients from Livestock Manure Applied to Pastureland
    Soupir, Michelle Lynn (Virginia Tech, 2003-07-24)
    Transport of fecal bacteria and nutrients from point and nonpoint sources to surface water bodies is of significant concern in Virginia and the United States. In Virginia, 4,320 river miles are impaired for one or more beneficial use and 72% of the streams are impaired due to pathogen indicators (VDEQ, 2002). Land applications of manure from confined animal systems and by direct deposit by grazing animals are both major sources of fecal bacteria and nutrients in runoff. Therefore, an understanding of the overland transport mechanisms for fecal bacteria and nutrients is very important for the development of best management practices to reduce loading of pathogens and nutrients to surface water bodies. The objectives of this study were to quantify the release and transport potential of three fecal bacterial indicators: E. coli, Enterococcus, and fecal coliforms; and nitrogen and phosphorus from land applied manure during runoff events. Another objective was to identify the Enterococcus species present in dairy manure and determine which species have the highest potential to be transported by runoff. Release plots were established to study the in-field bacteria and nutrient release. The bacteria and nutrients released from the plots are available to be transported to the edge of the field in runoff. Four manure treatments (turkey litter, liquid dairy manure, cowpies, and none or control) and three land type treatments: pasture with a history of poultry litter application (Turkey Farm), pasture with a history of liquid dairy manure application (Dairy Farm), and pasture with no prior manure application (Tech Research Farm) were studied. During a short but intense rainfall event, the highest bacterial release was measured under the cowpie treatment (E. coli concentrations ranging from 37,000 to >300,000 and FC concentrations ranging from 65,000 to >300,000). Pasturelands with a history of previous manure applications did not release higher bacteria concentrations compared with pasturelands which had never received manure applications. Pasturelands with a history of land application of liquid dairy manure and turkey litter had 143% and 94% higher TSS concentrations available to be transported off the field during overland flow events because of the build up of organic material on the soil surface. TP concentrations released from the cowpie, liquid dairy, and turkey litter treatments were 3.12 mg/L, 3.00 mg/L, and 1.76 mg/L, respectively. Transport plots were developed to measure the concentrations of fecal bacteria and nutrients present in overland flow at the edge of the field. The bacteria flow-weighted concentrations were highest in runoff samples from the plots treated with cowpies (200,000 CFU/100 mL of E. coli and 234,000 CFU/100 mL of FC). The turkey litter had the highest concentration of dissolved phosphorus in runoff from pasturelands (1.22 mg/L), but the cowpie treatment had the highest concentrations of sediment bound phosphorus in runoff (0.73 mg/L). All three treatments investigated in this study contributed to phosphorus loading in surface waters and could potentially increase the risk of eutrophication. Total nitrogen concentrations from the transport plots exceeded the threshold for likely eutrophication problems for all treatments and the total nitrogen concentrations from plots treated with cowpies exceeded the threshold for severe eutrophication problems. The Biolog System, a method of bacterial source tracking, was used to identify the different species of Enterococcus present both in the cowpie source manure and in the runoff collected from the transport plots treated with cowpies. The source manure is dominated by the Enterococcus mundtii (55%), Enterococcus gallinarum (20%), Enterococcus faecium (10%), and Enterococcus faecalis (10%). Enterococcus faecalis had the highest percentage of isolates present in runoff with a total of 37%, followed by Enterococcus mundtii which was present in 21% of the runoff events and Enterococcus gallinarum and Enterococcus faecium (11%). Improvements in understanding the bacterial release and overland processes will enhance modeling of bacteria and nutrient transport, and provide a basis for a more realistic evaluation of the impacts of management practices implementation. The data from this study will serve as a baseline to model the release and transport of fecal bacteria and nutrients from agricultural watersheds to surface waters.
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    Report of the Academic Advisory Committee to Virginia Department of Environmental Quality - Freshwater Nutrient Criteria
    Zipper, Carl E.; Benfield, Ernest F.; Dillaha, Theo A. III; Grizzard, Thomas J.; Hershner, Carl H.; Kator, Howard I.; Lung, Wu-Seng; Ney, John J.; Shabman, Leonard A.; Smith, Eric P.; Smock, Leonard A.; Walker, Jane L.; Yagow, Eugene R.; Younos, Tamim M. (Virginia Water Resources Research Center, 2004-07-20)
    The U.S. Environmental Protection Agency (EPA) requires all states to develop criteria to protect waters from impairment by nutrient enrichment. In this report, the AAC addresses general nutrient criteria development issues that face the Virginia Department of Environmental Quality (DEQ), responds to specific questions posed by DEQ, and provides additional background information that we hope will be of value to DEQ in the nutrient criteria development process.
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    Report of the Academic Advisory Committee to Virginia Department of Environmental Quality: Freshwater Nutrient Criteria for Rivers and Streams
    Zipper, Carl E.; Bukaveckas, Paul A.; Shabman, Leonard A.; Stephenson, Stephen Kurt; Yagow, Eugene R.; Smith, Eric P.; Smock, Leonard A.; Benfield, Ernest F.; Hershner, Carl H.; Kator, Howard I.; Lung, Wu-Seng; Walker, Jane L.; Younos, Tamim M. (Virginia Water Resources Research Center, 2006-06-12)
    This report describes an approach for establishing nutrient criteria in Virginia’s freshwater rivers and streams as recommended by the Academic Advisory Committee (AAC), an interdisciplinary team of scientists from Virginia’s colleges and universities. The report addresses questions raised by personnel from the Virginia Department of Environmental Quality (DEQ) and was prepared at the request of and in consultation with DEQ staff.
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    A "Screening Approach" for Nutrient Criteria in Virginia: Report of the Academic Advisory Committee for Virginia Department of Environmental Quality
    Zipper, Carl E.; Holtzman, Golde I.; Shabman, Leonard A.; Stephenson, Stephen Kurt; Walker, Jane L.; Yagow, Eugene R. (Virginia Water Resources Research Center, 2012-07)
    Under the Clean Water Act (CWA), criteria are components of water quality standards that are intended to protect designated uses for waters of the U.S. Nitrogen (N) and phosphorous (P) (“nutrients”) are common water contaminants that challenge conventional methods for establishing water quality criteria for an essential designated use, the protection of aquatic life. Unlike many water contaminants for which criteria have been established, nutrients typically do not exert primary effects on aquatic life by acting as toxicants. Excess nutrients in freshwater streams stimulate growth of algae that can impair stream communities by causing oxygen depletion and through other pathways. Because excess nutrients in surface waters are well known as stressors that impair aquatic life and impact other uses, the U.S. Environmental Protection Agency (EPA) is requiring CWA agencies throughout the U.S. to establish criteria for nutrients. The Academic Advisory Committee (AAC) to the Virginia Department of Environmental Quality (DEQ) has recommended a screening approach for nutrient criteria in Virginia as an alternative to single fixed-concentration numeric criteria as is commonly employed for conventional toxicants. Here, we investigate the potential to establish nutrient criteria using a screening approach by seeking to derive screening parameters from analyses of Virginia DEQ water monitoring data.