Development Of A Water Quality Model To Support A Pathogen Tmdl Newport Bay California
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Development Of A Water Quality Model To Support A Pathogen Tmdl Newport Bay California
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Author : John F. DeGeorge
language : en
Publisher:
Release Date : 2002-01-01
Development Of A Water Quality Model To Support A Pathogen Tmdl Newport Bay California written by John F. DeGeorge and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-01-01 with Water categories.
Development Of A Water Quality Model To Support Newport Bay California Tmdl
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Author : J. F. DeGeorge
language : en
Publisher: IWA Publishing
Release Date : 2003-02-01
Development Of A Water Quality Model To Support Newport Bay California Tmdl written by J. F. DeGeorge and has been published by IWA Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-02-01 with Science categories.
Newport Bay (Orange County, California) is listed by the California State Water Resources Control Board (SWRCB) as a water quality limited receiving water body because of sporadic exceedances of the fecal coliform water quality objectives for body contact recreation. Consistent with federal and state requirements, a Total Maximum Daily Load (TMDL) is being implemented in the watershed. The fecal coliform TMDL in Newport Bay is a phased approach for understanding and controlling the microbiological water quality in the to ensure the reasonable protection of the Bay?s beneficial uses. An important initial step within that TMDL was to assess the impairment of the body contact recreation beneficial use (REC-1) of Newport Bay receiving waters through characterizing the risk of illness associated with REC-1 exposure. A health risk assessment investigation was developed to characterize that risk. The health risk assessment investigation involved the integration of a population based model of disease transmission, a water quality modeling component necessary for estimating pathogen dose as part of the exposure assessment, and site-specific population use and receiving water data collection. The Water Environment Research Foundation funded the water quality modeling component of the health risk assessment investigation, which is the focus of this report. Also provided within this report is an overview of the health risk assessment methodology, a summary of the major findings from the risk assessment investigation, and a discussion of how the health risk methodology may be applied to other watersheds where impairment of the REC-1 beneficial use is in question. The major findings of the health risk assessment investigation indicated that (1) the risk of illness from REC-1 use in Newport Bay, estimated using two separate methods was generally below levels considered tolerable by US EPA, and (2) the reduction of controllable sources of pollution would not appreciably reduce the existing risk. Based on the collection of site-specific exposure data and the health risk characterization, it was determined that evaluating the impairment of the REC-1 beneficial use requires a more rigorous and comprehensive health based approach than that prescribed by the current regulations for recreational waters.
Assessing The Tmdl Approach To Water Quality Management
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2001-08-24
Assessing The Tmdl Approach To Water Quality Management written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-08-24 with Political Science categories.
Over the last 30 years, water quality management in the United States has been driven by the control of point sources of pollution and the use of effluent-based water quality standards. Under this paradigm, the quality of the nation's lakes, rivers, reservoirs, groundwater, and coastal waters has generally improved as wastewater treatment plants and industrial dischargers (point sources) have responded to regulations promulgated under authority of the 1972 Clean Water Act. These regulations have required dischargers to comply with effluent-based standards for criteria pollutants, as specified in National Pollutant Discharge Elimination System (NPDES) permits issued by the states and approved by the U.S. Environmental Protection Agency (EPA). Although successful, the NPDES program has not achieved the nation's water quality goals of "fishable and swimmable" waters largely because discharges from other unregulated nonpoint sources of pollution have not been as successfully controlled. Today, pollutants such as nutrients and sediment, which are often associated with nonpoint sources and were not considered criteria pollutants in the Clean Water Act, are jeopardizing water quality, as are habitat destruction, changes in flow regimes, and introduction of exotic species. This array of challenges has shifted the focus of water quality management from effluent-based to ambient- based water quality standards. Given the most recent lists of impaired waters submitted to EPA, there are about 21,000 polluted river segments, lakes, and estuaries making up over 300,000 river and shore miles and 5 million lake acres. The number of TMDLs required for these impaired waters is greater than 40,000. Under the 1992 EPA guidance or the terms of lawsuit settlements, most states are required to meet an 8- to 13-year deadline for completion of TMDLs. Budget requirements for the program are staggering as well, with most states claiming that they do not have the personnel and financial resources necessary to assess the condition of their waters, to list waters on 303d, and to develop TMDLs. A March 2000 report of the General Accounting Office (GAO) highlighted the pervasive lack of data at the state level available to set water quality standards, to determine what waters are impaired, and to develop TMDLs. This report represents the consensus opinion of the eight-member NRC committee assembled to complete this task. The committee met three times during a three-month period and heard the testimony of over 40 interested organizations and stakeholder groups. The NRC committee feels that the data and science have progressed sufficiently over the past 35 years to support the nation's return to ambient-based water quality management. Given reasonable expectations for data availability and the inevitable limits on our conceptual understanding of complex systems, statements about the science behind water quality management must be made with acknowledgment of uncertainties. This report explains that there are creative ways to accommodate this uncertainty while moving forward in addressing the nation's water quality challenges.
Structure And Effectiveness Of The State S Water Quality Programs
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Author :
language : en
Publisher:
Release Date : 2003
Structure And Effectiveness Of The State S Water Quality Programs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Environmental agencies categories.
Upper Newport Bay Ecosystem Restoration Feasibility Study
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Author :
language : en
Publisher:
Release Date : 2000
Upper Newport Bay Ecosystem Restoration Feasibility Study written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Upper Newport Bay Ecosystem Restoration Feasibility Study Orange County
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Author :
language : en
Publisher:
Release Date : 2000
Upper Newport Bay Ecosystem Restoration Feasibility Study Orange County written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
A Multi Model Approach To Predicting Pathogen Indicator Bacteria Loading In Tmdl Analyses
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Author : Donna-May G. Sakura-Lemessy
language : en
Publisher:
Release Date : 2009
A Multi Model Approach To Predicting Pathogen Indicator Bacteria Loading In Tmdl Analyses written by Donna-May G. Sakura-Lemessy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
This dissertation utilizes data from four sub-watersheds in the Little River Experimental Watershed, GA to develop models to improve forecast predictions related to the management of surface-water pollution due to non-point source runoff. Non-point source pollution is the primary cause of US surface-water quality impairment and a main transport mechanism for pathogens and other pollutants into receiving surface water bodies (US EPA 2008). In response to pollution reduction and watershed remediation mandates under the Federal Clean Water Act (1972)--particularly the Total Maximum Daily Load (TMDL) program--the role of water quality modeling in effectively rehabilitating impaired waters has taken on greater importance. Consequently, the significance of this study is that it is the first of its kind to incorporate a multi-model approach to address limitations in using single water quality models. In this regard, it builds on water quality engineering research by presenting methods to estimate contaminant concentrations and reduce uncertainty in overall model predictions in impaired water-bodies. Methodologically, the key point of departure in this dissertation is centered on the fact that water quality modeling is the cornerstone of TMDL analyses but the associated prediction uncertainty affects their adequacy in providing reliable contaminant loadings estimates in an impaired water body. As such, utilizing hydrological and water-quality process equations embedded in the two most widely used watershed-scale models, the Soil and Water Assessment Tool (SWAT) and Hydrological Simulation Program-Fortran (HSPF), and observed data from the sub-watersheds mentioned above, the dissertation addresses this limitation by combining results from the two competing models to reduce uncertainty and enhance accuracy of predictions. The study was conducted in two phases. First, HSPF and SWAT--two extensively-used, scientifically-rigorous, US EPA-approved watershed-scale codes--were used to build models of the four study catchments. The models were individually calibrated and shown (based on Nash-Sutcliffe Efficiency (NSE) ratios) to produce reliable simulations of the hydrologic and water quality conditions in the watershed. The second phase of the analysis involved using a multi-model approach to combine model forecasts. Model combination, introduced by Bates and Granger in 1969, has emerged as a viable analytical technique (Claesken and Hjort, 2008; Ajami et al., 2006) and widely-used across disciplines to improve model-forecasting results (Kim et al., 2006; Shamseldin et al., 1997; Granger, 2001; Clemens, 1989; Thompson, 1976; Newbold and Granger, 1974; Dickinson, 1973). After calibration, the model predictions were combined for each catchment using three different methods: the Weighted Average Method (WAM), the Nash-Sutcliffe Efficiency Maximization Method (NSE-max) and an Artificial Neural Network Method (ANN). Comparison of the results of the multi-model formulation with original individual model results showed improved estimates with all three combination methods. The improvement in model accuracy (based on NSE ratios) varied from modest to significant in both hydrologic and water quality variables. These improvements were attributed to a reduction in model structural uncertainty resulting from the ability to capture aspects of some of the more complex watershed interactions from exogenous information provided by the contributing models. It should be noted here, however, that as model availability increases, if additional models (beyond those utilized here) are used with this approach, care should be taken to ensure the credibility of each individual model for simulating the watershed scale processes under review. Limitations of this study include possible bias introduced by the use of deterministic models to estimate probabilistic contaminant distributions, limitations in available data, and the use of a seven-year study period that did not account for possible impacts of shorter periods of extreme hydrologic conditions on the individual model performances and model combination weightings. Recommendations for future research include (a) improving watershed-scale codes to better describe the probability distribution functions characteristic of contaminant distributions and data collection on wildlife species and populations; and investigating the fate and transport processes of pathogenic indicator bacteria deposited in forested areas and the impact of extreme hydrologic conditions on model performance and weighting. Overall, the findings from this dissertation suggest that water quality modeling incorporating a multi-model approach has the potential to significantly improve predictions compared to the predictions obtained when only one model is used. Clearly, the findings reported here have significant implications in improving TMDL analyses and remediation plans by presenting an approach that exploits the strengths of two of the most complete and well-accepted watershed-scale water quality models in the United States. Moreover, the findings of this dissertation auger well for the future of TMDL management in that it provides a more robust and cost effective basis for policy makers to decide on effective management strategies that incorporate acceptable risk, allowable loading and land use.
Water 21
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Author :
language : en
Publisher:
Release Date : 1999
Water 21 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Water quality management categories.
The British National Bibliography
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Author : Arthur James Wells
language : en
Publisher:
Release Date : 2006
The British National Bibliography written by Arthur James Wells and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Bibliography, National categories.
Structure And Effectiveness Of The State S Water Quality Programs
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Author :
language : en
Publisher:
Release Date : 2002
Structure And Effectiveness Of The State S Water Quality Programs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Environmental agencies categories.