In 2004, a field sampling study was initiated along the southern shoreline area of Lake Pontchartrain in Jefferson Parish, specifically, around Bonnabel Canal (Pumping Station No.1) to identify the effect of urban stormwater discharges on Lake Pontchartrain and to simulate the plume patterns from the Bonnabel Canal. Sixteen sampling stations were selected along the south shore of Lake Pontchartrain. Under dry weather conditions Fecal Coliform values exceeded the limit of 200 MPN/100mL at 3 of 16 stations. Fecal Coliform counts were found to be "wet" weather-dependent and unsuitable for primary contact recreation for at least three to four days following a pumping/rain event. A 3-D Hydrodynamic Model (COHERENS) and the TECPLOT™ equation feature were used for the prediction of contaminant plumes from the Bonnabel Canal into the Lake Pontchartrain. The model verified the three day wet weather effect of stormwater discharges along the shoreline of the study area.

A nested three dimensional numerical modeling application was developed to determine the fate of pathogen indicators in Lake Pontchartrain discharged from its tributaries. To accomplish this, Estuarine, coastal and ocean model with sediment (ECOMSED) was implemented to simulate various processes that would determine the fate and transport of fecal coliform bacteria in the lake. The processes included hydrodynamics, waves, sediment transport, and the decay and transport of the fecal coliforms. Wind and tidal effects were accounted along with the freshwater inflows. All the components of the modeling application were calibrated and validated using measured data sets. Field measurements of the conventional water quality parameters and fecal coliform levels were used to calibrate and validate the pathogen indicator transport. The decay of the fecal coliforms was based on the literature and laboratory tests. The sediment transport module was calibrated based on the satellite reflectance data in the lake. The north shore near-field model indicated that the fecal coliform plume can be highly dynamic and sporadic depending on the wind and tide conditions. It also showed that the period of impact due to a storm event on the fecal coliform levels in the lake can be anywhere from 1.5 days for a typical summer event to 4 days for an extreme winter event. The model studies showed that the zone of impact of the stormwater from the river was limited to a few hundred meters from the river mouth. Finally, the modeling framework developed for the north shore was successfully applied to the south shore of Lake Pontchartrain to simulate fate and transport of fecal coliforms discharged through the urban stormwater outfalls.

The Tangipahoa River and Natalbany River watersheds (Tangipahoa Parish/County) in the Lake Pontchartrain Basin (southeastern Louisiana) are experiencing rapid urbanization, particularly in the wake of the 2005 hurricane season. To document the impact of land use on water quality, thirty sites were monitored for surface water physiochemical, geochemical, and bacteriological parameters. Water quality data was compared to land use within four sub-watersheds of the Tangipahoa Watershed and three sub-watersheds of the Natalbany Watershed. Urbanization had the most profound impact on water quality of all land uses. In watersheds with little urban land cover (< 7% with the sub-watershed) waterbodies had low dissolved salt, nutrient, and fecal coliform concentrations and high dissolved oxygen levels. Waterbodies within the urban region (> 28% urban land cover within the sub-watershed) of the parish had significantly greater dissolved salt, nutrient, and fecal coliform concentrations and decreased dissolved oxygen concentrations. Specifically, nutrient and fecal coliform concentrations increased as streams flowed through urban areas. The specific conductance, fecal coliform counts, concentrations of sulfate, HCO3-C, sodium, and nutrients (NO3-N, NO2-N, NH4-N, and PO4-P), and the ratios of Na:Cl, Cl:Br, and SO4:Cl were shown to be the parameters most indicative of urban impacts. Many of the geochemical parameters correlated significantly with each other, particularly within the urban streams (the streams with the greatest concentrations). While fecal coliform counts were high within the urban streams, programs to address malfunctioning wastewater treatment plants (WWTP) appear to be working, with fecal coliform counts declining and dissolved oxygen levels rising during the course of the data collection. In contrast, sites undergoing rapid development showed an increase in turbidity levels and a decrease on dissolved oxygen levels (both going from healthy to unhealthy levels) during the 18-month course of the data collection. By understanding the impacts of urbanization on streams of the Gulf Coast, local and regional municipalities may be able to reduce the impacts in already urbanized areas or mitigate the impacts at the outset of development.

Under the Clean Water Act (CWA) program the Texas Commission on Environmental Quality (TCEQ) listed 110 stream segments with pathogenic bacteria impairment in 2000. The current study was conducted to characterize the watersheds associated with the impaired waterbodies. The main characteristics considered for the classification of waterbodies were designated use of the waterbody, land use distribution, density of stream network, average distance of a land of a particular use to the closest stream, household population, density of on-site sewage facilities (OSSF), bacterial loading due to the presence of different types of farm animals and wildlife, and average climatic conditions. The availability of observed in-stream fecal coliform bacteria concentration data was evaluated to obtain subgroups of data-rich and data-poor watersheds within a group. The climatic data and observed in-stream fecal coliform bacteria concentrations were analyzed to find out seasonal variability of the water quality. The watershed characteristics were analyzed using the multivariate statistical analysis techniques such as factor analysis/principal component analysis, cluster analysis, and discriminant analysis. Six groups of watersheds were formed as result of the statistical analysis. The main factors that differentiate the clusters were found to be bacterial contribution from farm animals and wildlife, density of OSSF, density of households connected to public sewers, and the land use distribution. Two watersheds were selected each from two groups of watersheds. Hydrological Simulation Program-FORTRAN (HSPF) model was calibrated for one watershed within each group and tested for the other watershed in the same group to study the similarity in the parameter sets due to the similarity in watershed characteristics. The study showed that the watersheds within a given cluster formed during the multivariate statistical analysis showed similar watershed characteristics and yielded similar model results for similar model input parameters. The effect of parameter uncertainty on the in-stream bacterial concentration predictions by HSPF was evaluated for the watershed of Salado Creek, in Bexar County. The parameters that control the HSPF model hydrology contributed the most variance in the in-stream fecal coliform bacterial concentrations corresponding to a simulation period between 1 January 1995 and 31 December 2000.

Under the Clean Water Act (CWA) program the Texas Commission on Environmental Quality (TCEQ) listed 110 stream segments with pathogenic bacteria impairment in 2000. The current study was conducted to characterize the watersheds associated with the impaired waterbodies. The main characteristics considered for the classification of waterbodies were designated use of the waterbody, land use distribution, density of stream network, average distance of a land of a particular use to the closest stream, household population, density of on-site sewage facilities (OSSF), bacterial loading due to the presence of different types of farm animals and wildlife, and average climatic conditions. The availability of observed in-stream fecal coliform bacteria concentration data was evaluated to obtain subgroups of data-rich and data-poor watersheds within a group. The climatic data and observed in-stream fecal coliform bacteria concentrations were analyzed to find out seasonal variability of the water quality. The watershed characteristics were analyzed using the multivariate statistical analysis techniques such as factor analysis/principal component analysis, cluster analysis, and discriminant analysis. Six groups of watersheds were formed as result of the statistical analysis. The main factors that differentiate the clusters were found to be bacterial contribution from farm animals and wildlife, density of OSSF, density of households connected to public sewers, and the land use distribution. Two watersheds were selected each from two groups of watersheds. Hydrological Simulation Program-FORTRAN (HSPF) model was calibrated for one watershed within each group and tested for the other watershed in the same group to study the similarity in the parameter sets due to the similarity in watershed characteristics. The study showed that the watersheds within a given cluster formed during the multivariate statistical analysis showed similar watershed characteristics and yielded similar model results for similar model input parameters. The effect of parameter uncertainty on the in-stream bacterial concentration predictions by HSPF was evaluated for the watershed of Salado Creek, in Bexar County. The parameters that control the HSPF model hydrology contributed the most variance in the in-stream fecal coliform bacterial concentrations corresponding to a simulation period between 1 January 1995 and 31 December 2000.

Gwinnett County, Georgia experienced rapid growth in the 1970’s without the infrastructure so septic systems were installed for residential homes. The number of septic systems grew to over 85,000 with a density of 487 septic systems per square mile. This study mapped the distribution of septic systems to determine regions of potential pathogen surface water. This study addressed what potential health risks do high density septic systems have on surface water quality and how can the history of Gwinnett County assist in future development in the Metropolitan Atlanta area? It was found that the density of septic systems has reduced the surface water quality for streams in the Yellow and Alcovy River basins. An average rainfall cause septic flushing and an increase in the fecal coliform. Other trends observed in the surface water quality of increased BOD, water temperature, and various metals also indicated this flushing effect.

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No description available.

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. / Master of Science

Fecal bacteria and pathogens are a major source of surface water impairment. In Virginia alone, approximately 73% of impaired waters are impaired due to fecal coliforms (FC). Because bacteria are a significant cause of water body impairment and existing bacterial models are predominantly based upon laboratory-derived information, bacterial models are needed that describe bacterial die-off and transport processes under field conditions. Before these bacterial models can be developed, more field-derived information is needed regarding bacterial survival and transport. The objectives of this research were to evaluate bacterial survival under field conditions and to develop a comprehensive, spatially variable (distributed) bacterial model that requires little or no calibration. Three field studies were conducted to determine die-off or diminution (settling plus die-off) rates of FC and Escherichia coli (EC) over time in: 1) dairy manure storage ponds and turkey litter storage sheds, 2) pasture and cropland soils to which dairy manure was applied, and 3) beef and dairy fecal deposits. The dairy manure storage ponds were sampled just under the pond surface. The FC and EC diminution (settling plus die-off) rates for dairy manure storage ponds were 0.00478 day⁻¹ and 0.00781 day⁻¹, respectively. The five samples collected for turkey litter in storage were inadequate to draw any conclusions. Bacterial die-off rates in cropland and pastureland soils were found to be statistically different from each other at the &alpha; = 0.05 level. The FC and EC die-off rates in cropland soils were 0.01351 day⁻¹ and 0.01734 day⁻¹, respectively, while the FC and EC die-off rates in pastureland soils were 0.02246 day⁻¹ and 0.02796 day⁻¹, respectively. Die-off rates for bacteria from dairy heifer, dairy milker, and beef cow fecal deposits were not statistically different from each other. The resulting die-off rate constants for fecal deposits were 0.01365 day⁻¹ and 0.01985 day⁻¹ for FC and EC, respectively. The EC/FC ratio was also evaluated for the fecal deposits and land-applied manure to determine if a quantifiable relationship was discernable. In general the EC/FC ratio declined over time, but no quantifiable relationship was discerned. The bacterial model simulates die-off, bacterial partitioning between soil and water, and bacterial transport to surface waters in free (in solution) and sediment-adsorbed forms. Bacterial die-off was modeled using Chick's Law, bacterial partitioning was modeled with a linear isotherm equation, and bacterial transport was modeled using continuity and flow equations. The bacterial model was incorporated into the ANSWERS-2000 model, a continuous, distributed, nonpoint source pollution model. The model was tested using data from two plot studies. Calibration was required to improve runoff and sediment predictions. Bacterial model predictions underpredicted bacterial concentrations in runoff with a maximum underprediction error of 92.9%, but predictions were within an order of magnitude in all cases. Further model evaluation, on a larger watershed with predominantly overland flow, over a longer time period, is recommended, but such data were not available at the time of this assessment. The overall conclusions of this research were 1) FC and EC die-off or diminution under the examined field conditions followed Chick's Law, 2) measured die-off rate constants in the field were much less than those cited in literature for laboratory experiments, and 3) for the conditions simulated for two plot studies, the bacterial model predicted bacterial concentrations in runoff within an order of magnitude. / Master of Science