Estimating Daily Potential E. coli Loads in Rural Texas Watersheds using Spatially Explicit Load Enrichment Calculation Tool (SELECT)

Borel, Kyna; Karthikeyan, Raghupathy; Smith, Patricia K.; Gregory, L.; Srinivasan, Raghavan

doi:10.21423/twj.v3i1.6164

Cited by 4 publications

References 5 publications

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A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

Parker¹,

Lopez²,

Karthikeyan

et al. 2015

Wildl. Res.

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Context Free-ranging mammals contribute to faecal pollution in United States water bodies. However, research into wildlife impact on water quality is dependent upon unreliable data (e.g. data uncertainty, unknown importance of parameters). Aims Our goal was to determine the potential impacts of common free-ranging mammal species and their management on Escherichia coli in the study floodplain. Our objectives for this research were to construct a model from study area- and literature-derived data, determine important species for E. coli deposition, and conduct sensitivity analyses on model parameters to focus future research efforts. Methods We constructed a model that incorporated parameters for four wildlife species known to contribute E. coli in central Texas: raccoons (Procyon lotor), white-tailed deer (Odocoileus virginianus), Virginia opossums (Didelphis virginiana), and wild pigs (Sus scrofa). These parameters were (1) population density estimates, (2) defaecation rates, (3) defaecation areas, (4) E. coli concentration in faecal material estimates, and (5) E. coli survival. We conducted sensitivity analyses on the model parameters to determine relative importance of each parameter and areas for additional study. Key results We found that adjustment of raccoon and Virginia opossum population densities had higher impacts on E. coli in the floodplain than similar changes in other species across all spatial and seasonal variations. We also found that the changes in E. coli survival, E. coli concentration in raccoon faecal material, and defaecation rates had the highest impacts on E. coli in the floodplain. Conclusions Our sensitivity analyses indicated that the largest impacts to projected E. coli loads were from changes in defaecation rates followed by E. coli concentration in faecal material and E. coli survival. Watershed planners, ranchers, and regulators must be cautioned that faecal deposition patterns are location specific and could significantly impact which species are considered the most important contributors. Implications Although all parameters require more research, we recommend that researchers determine defaecation rates for contributing species due to their relatively large impacts on E. coli in comparison to the other parameters. We also suggest additional research in free-ranging wildlife faecal morphology (form and structure) and area of deposition. Finally, species-specific E. coli survival studies for free-ranging wildlife should be conducted.

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A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

Parker¹,

Lopez²,

Karthikeyan

et al. 2015

Wildl. Res.

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Estimating E. coli and Enterococcus loads in a coastal Texas watershed

Borel

Karthikeyan

Berthold

et al. 2015

Texas Water Journal

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Pathogens are the principal cause of water body impairment for 303(d) listed waters in Texas and across the United States with 10,654 impairments nationally (TCEQ 2012; USEPA 2013). In Texas, 45% of 568 total impairments are caused by elevated bacteria levels (TCEQ 2012). Models such as the Soil and Water Assessment Tool (SWAT) and Hydrological Simulation Program-FORTRAN (HSPF) have been used for assessing bacterial sources and loading. Other simplistic microbial models, such as the Potential Nonpoint Pollution Index (PNPI), Spatially Explicit Delivery MODel (SEDMOD), and Spatially Explicit Load Enrichment Calculation Tool (SELECT), have been developed to rank potential pollution impacts from nonpoint sources and identify critical areas primarily using land use and geomorphology. Citation: Borel K, Karthikeyan R, Berthold TA, Wagner K. 2014. Estimating E. coli and Enterococcus loads in a coastal Texas watershed. Texas Water Journal. 6(1):33-44. Available from: https://doi.org/10.21423/twj.v6i1.7008.

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Modeling bacterial load scenarios in a Texas coastal watershed to support decision-making for improving water quality

Glenn

Bare

Neish

2017

Texas Water Journal

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The planning for improved health of a stream can be optimized by assessing the watershed system as a whole; state and federal agencies have embraced this watershed approach for managing water quality (USEPA 2008). Using the watershed approach, bacteria loads in the Double Bayou watershed were modeled to identify critical loading areas and develop appropriate voluntary management measures as part of a watershed protection plan. The Spatially Explicit Load Enrichment Calculation Tool (SELECT) model was developed by the Department of Biological and Agricultural Engineering and the Spatial Science Laboratory at Texas A&M University to estimate potential pollutant loadings from fecal indicator bacteria. For this study, SELECT modeling was performed to estimate bacterial loadings from the distribution of livestock, wildlife, a wastewater treatment facility, and on-site sewage facilities. Rankings of each contributing source were assessed for the entire watershed. The objective of this study was to analyze the success of using SELECT to evaluate bacteria loads in a rural coastal watershed; results showed SELECT was successful in the Double Bayou watershed in ranking categories of bacteria sources and revealing spatial load aggregations. This analysis guides discussion on the prioritization of management measures to improve water quality in the Double Bayou watershed. Citation: Glen SM, Bare RM, Neish BS. 2017. Modeling bacterial load scenarios in a Texas coastal watershed to support decision-making for improving water quality. Texas Water Journal. 8(1):57-66. Available from: https://doi.org/10.21423/twj.v8i1.7048.

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Estimating Daily Potential E. coli Loads in Rural Texas Watersheds using Spatially Explicit Load Enrichment Calculation Tool (SELECT)

Cited by 4 publications

References 5 publications

A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

Estimating E. coli and Enterococcus loads in a coastal Texas watershed

Modeling bacterial load scenarios in a Texas coastal watershed to support decision-making for improving water quality

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