Showing papers on "Nonpoint source pollution published in 2006"

A modeling approach to evaluate the impacts of water quality management plans implemented in a watershed in Texas

Abstract: Several best management practices (BMPs) have been implemented through Water Quality Management Plans (WQMPs) in the West Fork Watershed of Trinity River Basin in Texas, USA, where nonpoint source pollution is a serious concern. Major sources of pollution are sediment erosion and nutrients. The objective of this study was to evaluate the long-term impact of implementation of WQMPs on nonpoint source pollution at the farm level and watershed level using a modeling approach. The Soil and Water Assessment Tool watershed model was applied to quantify the impacts of implementing WQMPs on sediment and nutrients. A preBMP scenario representing conditions of the watershed prior to the implementation of WQMPs, and a post-BMP scenario representing the conditions of the watershed after implementation of WQMPs were simulated to estimate the reductions in nonpoint source pollution due to WQMP implementation. The results are presented as percentage reductions in sediment and nutrient loadings, at the farm level and at two locations within the watershed. The results revealed that (a) the benefits of the WQMPs were greater (up to 99%) at the farm level and (b) the benefits due to WQMPs were 1e2% at the watershed level. Watershed level benefits are tangible as the WQMP implementation area is very small compared to the watershed area. An additional scenario was evaluated to show the possible impacts of expanding the current BMP effort on load reductions. This study showed that a modeling approach can be used to estimate the impacts of water quality management programs in large watersheds. 2005 Elsevier Ltd. All rights reserved.

Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States

Abstract: Two nonlinear models were developed at the national scale to (1) predict contamination of shallow ground water (typically < 5 m deep) by nitrate from nonpoint sources and (2) to predict ambient nitrate concentration in deeper supplies used for drinking. The new models have several advantages over previous national-scale approaches. First, they predict nitrate concentration (rather than probability of occurrence), which can be directly compared with water-quality criteria. Second, the models share a mechanistic structure that segregates nitrogen (N) sources and physical factors that enhance or restrict nitrate transport and accumulation in ground water. Finally, data were spatially averaged to minimize small-scale variability so that the large-scale influences of N loading, climate, and aquifer characteristics could more readily be identified. Results indicate that areas with high N application, high water input, well-drained soils, fractured rocks or those with high effective porosity, and lack of attenua...

Estimating the benefits of water quality improvements under the Water Framework Directive: are benefits transferable?

Abstract: The Water Framework Directive sets an objective of ‘Good Ecological Status’ for water bodies across the EU. Non-point pollution from agriculture is a major reason for the failure of rivers in the UK to meet this target. In this paper, we use choice experiment methodology to test the transferability of benefit estimates of water quality improvements for two small catchments where agricultural-source non-point pollution and irrigation water abstraction are the main threats to ecological status. We also investigate the most appropriate techniques to apply to transfer testing, including allowing for correlation between preferences for environmental attributes, and testing for acceptable differences between transferred and original values.

Transport Of Fecal Bacteria From Poultry Litter and Cattle Manures Applied to Pastureland

Abstract: Land applications of manure from confined animal systems and direct deposit by grazing animals are both major sources of bacteria in streams. An understanding of the overland transport mechanisms from land applied waste is needed to improve design of best management practices (BMPs) and modeling of nonpoint source (NPS) pollution. Plots were established on pasturelands receiving phosphorus-based livestock waste applications to measure the concentrations of Escherichia coli (E. coli), fecal coliform (FC), and Enterococcus present in overland flow at the edge of the field. The flow-weighted bacteria concentrations were highest in runoff samples from the plots treated with cowpies (1.37×105 colony forming units (cfu)/100 ml of E. coli) followed by liquid dairy manure (1.84×104 cfu/100 ml of E. coli) and turkey litter (1.29×104 cfu/100 ml of E. coli). The temporal distribution of fecal bacterial concentrations appeared to be dependent upon both the animal waste treatment and the indicator species, with peak concentrations occurring either at the beginning of the runoff event or during peak flow rates. BMPs could be selected to reduce peak flows or first flush effects depending upon the litter or manure applied to the land. The commercial Biolog System was used to identify the dominant species of Enterococcus present in the cowpie source manure (Enterococcus mundtii 55%) and in the runoff collected from the transport plots treated with cowpies (Enterococcus faecalis 37%). The identification of predominant species of Enterococcus that are associated with specific sources of fecal pollution could greatly assist with identifying the origins of NPS pollution.

Basin-Wide Analysis of the Dynamics of Fecal Contamination and Fecal Source Identification in Tillamook Bay, Oregon

Abstract: The objectives of this study were to elucidate spatial and temporal dynamics in source-specific Bacteroidales 16S rRNA genetic marker data across a watershed; to compare these dynamics to fecal indicator counts, general measurements of water quality, and climatic forces; and to identify geographic areas of intense exposure to specific sources of contamination. Samples were collected during a 2-year period in the Tillamook basin in Oregon at 30 sites along five river tributaries and in Tillamook Bay. We performed Bacteroidales PCR assays with general, ruminant-source-specific, and human-source-specific primers to identify fecal sources. We determined the Escherichia coli most probable number, temperature, turbidity, and 5-day precipitation. Climate and water quality data collectively supported a rainfall runoff pattern for microbial source input that mirrored the annual precipitation cycle. Fecal sources were statistically linked more closely to ruminants than to humans; there was a 40% greater probability of detecting a ruminant source marker than a human source marker across the basin. On a sample site basis, the addition of fecal source tracking data provided new information linking elevated fecal indicator bacterial loads to specific point and nonpoint sources of fecal pollution in the basin. Inconsistencies in E. coli and host-specific marker trends suggested that the factors that control the quantity of fecal indicators in the water column are different than the factors that influence the presence of Bacteroidales markers at specific times of the year. This may be important if fecal indicator counts are used as a criterion for source loading potential in receiving waters.

Nitrogen and Irrigation Management Practices to Improve Nitrogen Uptake Efficiency and Minimize Leaching Losses

Abstract: Summary Nitrogen (N) is the most important nutrient for plant growth and production. Nitrogen uptake efficiency is dependent on a number of factors. Water management influences the transformation of N sources applied to the soil and transport of the nitrate form of N in the soil. Nitrate-N is the final product of N transformations and is quite mobile in soils with the water front. Leaching of nitrate below the rootzone is an economic loss and contributes to non-point source pollution of groundwater. In this chapter we summarize the factors influencing the N uptake efficiencies for various crops and production systems, and chemical and biological processes that influence the N transformation or losses. Recent advances leading to development of N and irrigation best management practices that support sustainable crop production and net returns while minimizing the non-point source nitrate pollution of ground-water are also discussed.

Water-Quality Engineering in Natural Systems

Abstract: PREFACE. 1 INTRODUCTION. 1.1 Principles of Water-Quality Control. 1.2 Sources of Water Pollution. 1.2.1 Point Sources. 1.2.2 Nonpoint Sources. 1.3 Laws and Regulations. 1.3.1 Clean Water Act. 1.3.2 Safe Drinking Water Act. 1.4 Strategy for Water-Quality Management. 1.4.1 Use-Attainability Analysis. 1.4.2 Total Maximum Daily Load Process. Summary. Problems. 2 WATER-QUALITY STANDARDS. 2.1 Introduction. 2.2 Measures of Water Quality. 2.2.1 Physical Measures. 2.2.2 Chemical Measures. 2.2.3 Biological Measures. 2.3 U.S. Surface-Water Standards. 2.3.1 Designated Beneficial Uses. 2.3.2 Water-Quality Criteria. 2.3.3 Antidegradation Policy. 2.3.4 General Water-Quality Management Practices. 2.4 U.S. Ground-Water Standards. 2.5 Background Water Quality. 2.6 Computer Codes. Summary. Problems. 3 FATE AND TRANSPORT IN AQUATIC SYSTEMS. 3.1 Mixing of Dissolved Constituents. 3.2 Properties of the Diffusion Equation. 3.2.1 Fundamental Solution in One Dimension. 3.2.2 Principle of Superposition. 3.2.3 Solutions in Higher Dimensions. 3.2.4 Moment Property of the Diffusion Equation. 3.2.5 Nondimensional Form. 3.3 Transport of Suspended Particles. Summary. Problems. 4 RIVERS AND STREAMS. 4.1 Introduction. 4.2 Transport Processes. 4.2.1 Initial Mixing. 4.2.2 Longitudinal Dispersion. 4.3 Spills. 4.3.1 Governing Equation. 4.3.2 Fate of Volatile Organic Compounds in Streams. 4.4 Continuous Discharges. 4.4.1 Oxygen Demand of Wastewater. 4.4.2 Reaeration. 4.4.3 Streeter-Phelps Model. 4.4.4 Other Considerations. 4.5 Restoration and Management. 4.5.1 Nonstructural Techniques. 4.5.2 Structural Techniques. 4.6 Computer Codes. Summary. Problems. 5 LAKES AND RESERVOIRS. 5.1 Introduction. 5.2 Natural Processes. 5.2.1 Flow and Dispersion. 5.2.2 Light Penetration. 5.2.3 Sedimentation. 5.2.4 Eutrophication and Nutrient Recycling. 5.2.5 Thermal Stratification. 5.3 Water-Quality Models. 5.3.1 Zero-Dimensional (Completely Mixed) Model. 5.3.2 One-Dimensional (Vertical) Models. 5.3.3 Two-Dimensional Models. 5.4 Restoration and Management. 5.4.1 Control of Eutrophication. 5.4.2 Control of Dissolved-Oxygen Levels. 5.4.3 Control of Toxic Contaminants. 5.4.4 Control of Acidity. 5.4.5 Control of Aquatic Plants. 5.4.6 Attainability of Lake Uses. 5.5 Computer Codes. Summary. Problems. 6 WETLANDS. 6.1 Introduction. 6.2 Natural Wetlands. 6.2.1 Marshes. 6.2.2 Swamps. 6.2.3 Bogs. 6.2.4 Fens. 6.3 Delineation of Wetlands. 6.3.1 Vegetation. 6.3.2 Soils. 6.3.3 Hydrology. 6.4 Wetland Hydrology. 6.4.1 Net Surface-Water Inflow. 6.4.2 Net Ground-Water Inflow. 6.4.3 Evapotranspiration. 6.5 Case Study: The Everglades and Big Cypress Swamp. 6.6 Constructed Treatment Wetlands. 6.6.1 Surface-Flow Wetlands. 6.6.2 Subsurface-Flow Wetlands. 6.6.3 Wetland Regulations in the United States. 6.6.4 Basic Principles for Wetland Restoration and Creation. 6.6.5 Design of Constructed Treatment Wetlands. 6.6.6 Wetlands for Treating Roadway Runoff. Summary. Problems. 7 GROUND WATER. 7.1 Introduction. 7.2 Natural Ground-Water Quality. 7.3 Contaminant Sources. 7.3.1 Septic Tanks. 7.3.2 Leaking Underground Storage Tanks. 7.3.3 Land Application of Wastewater. 7.3.4 Irrigation and Irrigation Return Flow. 7.3.5 Solid-Waste Disposal Sites. 7.3.6 Waste-Disposal Injection Wells. 7.3.7 Agricultural Operations. 7.4 Fate and Transport Models. 7.4.1 Instantaneous Point Source. 7.4.2 Continuous Point Source. 7.4.3 Continuous Plane Source. 7.5 Transport Processes. 7.6 Fate Processes. 7.6.1 Sorption. 7.6.2 First-Order Decay. 7.6.3 Combined Processes. 7.7 Nonaqueous-Phase Liquids. 7.8 Remediation of Subsurface Contamination. 7.8.1 Remediation Goals. 7.8.2 Site Investigation. 7.8.3 Remediation Strategies. 7.9 Computer Models. Summary. Problems. 8 OCEANS AND ESTUARIES. 8.1 Introduction. 8.2 Ocean-Outfall Discharges. 8.2.1 Near-Field Mixing. 8.2.2 Far-Field Mixing. 8.3 Water-Quality Control in Estuaries. 8.3.1 Classification of Estuaries. 8.3.2 Physical Conditions. 8.3.3 Chemical Conditions. 8.3.4 Biological Conditions. 8.3.5 Use-Attainability Evaluations. 8.4 Computer Models. Summary. Problems. 9 WATERSHEDS. 9.1 Introduction. 9.2 Source-Water Protection. 9.3 Watershed-Generated Pollutant Loads. 9.4 Urban Watersheds. 9.4.1 Sources of Pollution. 9.4.2 Fate and Transport Processes. 9.4.3 Best Management Practices. 9.5 Agricultural Watersheds. 9.5.1 Sources of Pollution. 9.5.2 Fate and Transport Processes. 9.5.3 Best Management Practices. 9.6 Airsheds. 9.6.1 Nitrogen Compounds. 9.6.2 Mercury. 9.6.3 Other Metals. 9.6.4 Pesticides. 9.6.5 Combustion Emissions. 9.7 Computer Models. Summary. Problems. APPENDIX A UNITS AND CONVERSION FACTORS. A.1 Units. A.2 Conversion Factors. APPENDIX B FLUID PROPERTIES. B.1 Water. B.2 Organic Compounds Found in Water. B.3 Air at Standard Atmospheric Pressure. APPENDIX C U.S.WATER-QUALITY STANDARDS. C.1 Water-Quality Criteria for Surface Waters. C.2 Water-Quality Criteria for Drinking Water. C.3 Priority Pollutants. APPENDIX D STATISTICAL TABLES. D.1 Areas Under the Standard Normal Curve. APPENDIX E SPECIAL FUNCTIONS. E.1 Error Function. E.2 Bessel Functions. E.2.1 Definition. E.2.2 Evaluation of Bessel Functions. E.3 Gamma Function. APPENDIX F PIPE SPECIFICATIONS. F.1 PVC Pipe. F.2 Ductile Iron Pipe. F.3 Concrete Pipe. REFERENCES. INDEX.

Modeling of non-point source pollution in a Mediterranean drainage basin

Abstract: SWAT ver. 2000 was used to predict hydrographs, and sediment, nitrate and total phosphorus loadings from a 1349 km2 mountainous/agricultural watershed in Northern Greece. The model was calibrated and verified using continuous meteorological data from eight stations within the drainage area, and runoff, sediment and nutrient concentrations measured at nine stations located within the main tributaries of the watershed, for the time period from May 1st, 1998 to January 31st, 2000. Model validation methodology and resulting input parameters appropriate for Mediterranean drainage basins are presented. Predicted by the model hydrographs, sedimentographs and pollutographs are plotted against observed values and show good agreement. Model performance is evaluated using the root mean square error computation and scattergrams of predicted versus observed data. The validated model is also used to test the effectiveness of three alternative cropping scenarios in reducing nutrient loadings from the agricultural part of the watershed. The study showed that this model, if properly validated, can be used effectively in testing management scenarios in Mediterranean drainage basins.

Water Quality Modeling

Abstract: Water quality forecasts are vital to determining limitations for point source waste loads and diffuse or nonpoint source loads required to meet water quality standards in streams, lakes, and estuaries. Only mechanistic water quality modeling is widely applicable for forecasting. Although surface water quality modeling has a sound interdisciplinary scientific basis, the use of these analysis tools are limited in regulatory and resource decision making by a lack of a professional consensus defining model application protocols. To analyze water quality problems, (i) the uses for a water body must be evaluated, (ii) models must be calibrated and tested to relate impaired water quality to the waste sources, (iii) a formal uncertainty analysis must define a margin of safety to protect human and ecological health, and (iv) when necessary, an economic analysis must be performed to determine if the designated uses are reasonably achievable. Keywords: water quality; standards; streams; lakes; estuaries; watersheds; point sources; diffuse or nonpoint sources; total maximum daily loads (TMDL); waste load allocation; forecasts; hind casts; mechanistic cause-and-effect modeling; probabilistic modeling; uncertainty analysis; monte carlo analysis; margin of safety; calibration and statistical testing; sensitivity testing: economic analysis; newton's second law; conservation of momentum, mass and energy; fick's law; advective-diffusion; hydraulics; hydrodynamics; second law of thermodynamics; geomorphology; decision making

Evaluation of annualized agricultural nonpoint source model for a watershed in the Siwalik Hills of Nepal

Abstract: A study was undertaken to determine the predictive capability of Annualized Agricultural NonPoint Source (AnnAGNPS) model with respect to runoff volume, peak flows, and sediment yield from a 130.8 ha watershed in the Siwalik Hills of Nepal. AnnAGNPS simulations are compared with two years of field observations from the study watershed. The model predicted the runoff volume within the range of acceptable accuracy. The event-based peak flows were overpredicted by 105% with R 2 of 0.85 during calibration and 162% with R 2 of 0.77 during validation. Similarly, the model overpredicted the event-based sediment yield by 59% with R 2 of 0.63 during calibration and 92% with R 2 of 0.59 during validation. These results show that the model performs well in simulating runoff volumes compared to the peak flows and sediment yields. It is observed that there is a need to modify or improve the estimation methods of the peak flow and sediment yield to increase the performance of the model which can aid watershed management in local conditions.

Watershed-Scale Impacts of Forest Buffers on Water Quality and Runoff in Urbanizing Environment

Abstract: Forestry practices that are applied to buffer regions can be used as a strategy to improve water quality and flow regime in urbanizing watersheds. This study evaluates watershed-wide impacts of buffering urban forestry practices. Watershed simulation modeling is used to study the effectiveness of best management practices (BMPs) scenarios representing riparian and street buffers on water quality, quantity, and open space in rural, suburban, and urbanized environments. Results indicate that the watershed health can be improved through location-specific application of urban forestry practices. The proportion of urban forest cover reduced sediment and nutrient loading, decreased stormwater runoff, and increased groundwater recharge in urbanizing watersheds. Reduction in variability of watershed processes indicate that forest BMPs make the watershed more adaptive to handling adverse conditions, such as large storms, nonpoint source pollution, flooding, and high winds. Watersheds that are starting to get urbanized responded well to the BMP scenarios compared to more urbanized subbasins. General strategies include a focus on increasing pervious cover of the watershed with a higher priority in riparian and street buffers. Specific tree species and practical issues in forest buffering are also discussed. Policies like financial incentives and encouraging voluntary participation can be used to improve urban watersheds.

Water Quality Trends in a Coastal Lagoon Impacted by Non-point Source Pollution after Implementation of Protective Measures

Abstract: Water quality data from two different monitoring periods are used to evaluate the trophic state and effectiveness of various protective measures on the restoration of a eutrophic, coastal Mediterranean lagoon. Main protective measures included elimination of municipal/industrial raw wastewater discharges in the rivers outflowing to the lagoon, sediment/erosion control practices in the lagoon’s drainage basin (i.e., construction of sediment/debris dams and grade control structures, reforestation and ban on livestock grazing), and reduction of fertilizer application quantities as a result of changes in crops. Water quality data include, among others, chlorophyll a, dissolved oxygen and nutrient concentrations, various physicochemical parameters, and transparency, measured during two monitoring periods, i.e., before (1983–84) and after (1998–99) implementation of protective measures. Rainfall depth for the two time periods was also available. Empirical equations were developed, from statistical analyses of the data, relating the water quality parameters during the two monitoring periods. These models help identify water quality trends. Based on the analyses, it seems that measures were effective in reducing sediments transported into the lagoon. However, the lagoon remains eutrophic to hypereutrophic, mostly due to phosphorus released in the water column from bottom sediments. Therefore, future restoration efforts should be directed towards the management of bottom sediments.

Agricultural Land Use and Best Management Practices to Control Nonpoint Water Pollution

Abstract: In recent years, improvements in point-source depuration technologies have highlighted the problems regarding agricultural nonpoint (diffuse) sources, and this issue has become highly relevant from the environmental point of view. The considerable extension of the areas responsible for this kind of pollution, together with the scarcity of funds available to local managers, make minimizing the impacts of nonpoint sources on a whole basin a virtually impossible task. This article presents the results of a study intended to pinpoint those agricultural areas, within a basin, that contribute most to water pollution, so that operations aimed at preventing and/or reducing this kind of pollution can be focused on them. With this aim, an innovative approach is presented that integrates a field-scale management model, a simple regression model, and a geographic information system (GIS). The Lake Vico basin, where recent studies highlighted a considerable increase in the trophic state, mainly caused by phosphorus (P) compounds deriving principally from the intensive cultivation of hazelnut trees in the lake basin, was chosen as the study site. Using the management model Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), the consequences, in terms of sediment yield and phosphorus export, of hazelnut tree cultivation were estimated on different areas of the basin with and without the application of a best management practice (BMP) that consists of growing meadow under the trees. The GLEAMS results were successively extended to basin scale thanks to the application of a purposely designed regression model and of a GIS. The main conclusions can be summarized as follows: The effectiveness of the above-mentioned BMP is always greater for erosion reduction than for particulate P reduction, whatever the slope value considered; moreover, the effectiveness with reference to both particulate P and sediment yield production decreases as the slope increases. The proposed approach, being completely distributed, represents a considerable step ahead compared to the semidistributed or lumped approaches, which are traditionally employed in research into tools to support the decision-making process for land-use planning aimed at water pollution control.

Organophosphorus insecticides in agricultural and residential runoff: field observations and implications for total maximum daily load development.

Abstract: Development of total maximum daily loads (TMDLs) for nonpoint source pollutants requires mass flux estimates for targeted compounds from contributing sources. We measured organophosphorus insecticide concentrations in surface runoff from agricultural and residential land-use sites in a southern Californian watershed over the course of runoff-producing irrigation and rainfall events. Event mean concentrations (EMCs) for chlorpyrifos, diazinon, and malathion exhibited considerable variability among irrigation and storm runoff events at agricultural sites; residential storm runoff EMCs for these compounds were considerably less variable. Event loads and EMCs were higher for runoff events following reported insecticide applications. Organophosphorus insecticide EMCs were not consistently correlated with hydrologic characteristics of runoff events. Our results indicate that on an area basis, loads from residential land may exceed those from sites planted in row crops for a given rainfall depth, suggesting that...

An approach for using soil surveys to guide the placement of water quality buffers

Abstract: Vegetative buffers may function better for filtering agricultural runoff in some locations than in others because of intrinsic characteristics of the land on which they are placed. The objective of this study was to develop a method based on soil survey attributes that can be used to compare soil map units for how effectively a buffer installed in them could remove pollutants from crop field runoff. Three separate models were developed. The surface runoff models for sediment and for dissolved pollutants were quantitative, based mainly on slope, soil, and rainfall factors of the Revised Universal Soil Loss Equation (RUSLE), and were calibrated using the Vegetative Filter Strip Model (VFSMOD) for a standard buffer design and field management. The groundwater model categorized map units by the presence or absence of suitably-shallow groundwater and hydric conditions for interaction with the root zone of a buffer. The models were applied to a ~65 km 2 (~25 mi 2 ) agricultural watershed in northwestern Missouri. Data acquisition, calculations, and map production utilized the Soil Survey Geographic Database (SSURGO). For surface runoff, soil survey-based values correlated strongly with corresponding VFSMOD estimates for sediment (R 2 = 0.94) and dissolved pollutant trapping efficiency (R 2 = 0.83) for a wide range of soil, slope, and rainfall conditions. A strong negative correlation between trapping efficiency and field runoff load was indicated. Mapped results revealed large differences in buffer capability for surface runoff across the test watershed (21 to 99 percent for sediment and seven to 47 percent for dissolved pollutants). Trapping efficiency for dissolved pollutants was much smaller than for sediment in every map unit. Lower values of trapping efficiency were associated with map units where runoff loads are higher and where a buffer will trap greater loads of sediment, but smaller loads of dissolved pollutants, than in units with higher values. Comparative rankings can be adjusted somewhat for site conditions that depart from the reference conditions, and recalibration may be desired to better account for them. For groundwater, the confluence of hydric conditions and shallow water table occurred only in the highest reaches of the test watershed, but a buffer can also interact with groundwater in most upland and riparian locations due to the prevalence of a seasonally shallow water table. By this approach, soil surveys may be used as a screening tool to guide planners to locations where buffers are likely to have a greater impact on water quality and away from those where impact is likely to be small.

The Impact of Runoff Generation Mechanisms on the Location of Critical Source Areas

Abstract: Identifying phosphorus (P) source areas and trans- port pathways is a key step in decreasing P loading to natural water systems. This study compared the effects of two mod- eled runoff generation processes - saturation excess and infil- tration excess - on total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations in 10 catchment streams of a Catskill mountain watershed in southeastern New York. The spatial distribution of runoff from forested land and agricultural land was generated for both runoff processes; results of both distributions were consistent with Soil Conservation Service- Curve Number (SCS-CN) theory. These spatial runoff distribu- tions were then used to simulate stream concentrations of TP and SRP through a simple equation derived from an observed relation between P concentration and land use; empirical results indicate that TP and SRP concentrations increased with increasing percentage of agricultural land. Simulated TP and SRP stream concentrations predicted for the 10 catchments were strongly affected by the assumed runoff mechanism. The modeled TP and SRP concentrations produced by saturation excess distribution averaged 31 percent higher and 42 percent higher, respectively, than those produced by the infiltration excess distribution. Misrepresenting the primary runoff mecha- nism could not only produce erroneous concentrations, it could fail to correctly locate critical source areas for implementation of best management practices. Thus, identification of the pri- mary runoff mechanism is critical in selection of appropriate models in the mitigation of nonpoint source pollution. Correct representation of runoff processes is also critical in the future development of biogeochemical transport models, especially those that address nutrient fluxes. (KEY TERMS: nonpoint source pollution; land use/land cover; runoff modeling; watershed management; TMDL; phosphorus.)

A water quality‐based approach for watershed wide bmp strategies1

Abstract: Watershed management strategies generally involve controlling nonpoint source pollution by implementing various best management practices (BMPs). Currently, stormwater management programs in most states use a performance-based approach to implement onsite BMPs. This approach fails to link the onsite BMP performance directly to receiving water quality benefits, and it does not take into account the combined treatment effects of all the stormwater management practices within a watershed. To address these issues, this paper proposes a water quality-based BMP planning approach for effective nonpoint source pollution control at a watershed scale. A coupled modeling system consisting of a watershed model (HSPF) and a receiving water quality model (CE-QUAL-W2) was developed to establish the linkage between BMP performance and receiving water quality targets. A Monte Carlo simulation approach was utilized to develop alternative BMP strategies at a watershed level. The developed methodology was applied to the Swift Creek Reservoir watershed in Virginia, and the results show that the proposed approach allows for the development of BMP strategies that lead to full compliance with water quality requirements.

The Economics of Water Quality

Abstract: Contents: Series preface Introduction. Part I Managing Alternative Sources of Water Pollution: Industrial Water Pollution: Environmental regulation, investment timing and technology choice, Wayne B. Gray and Ronald J Shadbegian Industrial pollution in economic development: the environmental Kuznets curve revisited, Hemamala Hettige, Muthukumara Mani and David Wheeler The cost of water pollution regulation in the pulp and paper industry, John D. McClelland and John K. Horowitz. Agricultural Water Pollution: Dynamics of agricultural groundwater extraction, Petra Helleger, David Zilberman and Ekko van Ierland Optimal self-protection from nitrate-contaminated groundwater, Richard C. Ready and Kimberly Henken Economic risk and water quality protection in agriculture, Darrell J. Bosch and James W Pease Endogenous transport coefficients, Anastasia M. Lintner and Alfons Weersink. Part II Alternative Instruments for Controlling Water Pollution: Regulation, Standards, Taxes, Subsidies and Liability for Water Quality: Agricultural runoff as a nonpoint externality: a theoretical development, Ronald C. Griffin and Daniel W Bromley Agricultural pollution control under Spanish and European environmental policies, Yolanda Martinez and Jose Albiac Land retirement as a tool for reducing agricultural nonpoint source pollution, Marc O. Ribaudo, C. Tim Osborn and Kazim Konyor Modeling regional irrigation decisions and drainage pollution control, Ariel Dinar, Stephen A. Hatchett and Edna J. Loehman Liability for groundwater contamination from pesticides, Kathleen Segerson. Water Pollution Permits and Nutrient Trading to Improve Water Quality: The structure and practice of water quality trading markets, Richard T. Woodward, Ronald A. Kaiser and Aaron-Marie B. Wicks Transferable discharge permits and economic efficiency: the Fox river, William O'Neal, Martin David, Christina Moore and Erhard Joeres Point-nonpoint nutrient trading in the Susquehanna river basin, Richard D. Horan, James S. Shortle and David G. Abler Point/nonpoint reduction trading: an interpretive survey, David Letson Point/nonpoint source trading of pollution abatement: choosing the right trading ratio, Arun S. Malik, David Letson and Stephen R. Crutchfield A trading-ration system for trading water pollution discharge permits, Ming-Feng Hung and Diagee Shaw. Part III Returns from Clean Water: Provision of Clean water: The economics of safe drinking water, Robert Innes and Dennis Cory Economic objectives within a bureaucratic decision process: setting pollution control requirements under the Clean Water Act, Arthur G. Fraas and Vincent G. Munley. Willingness to Pay to Prevent Water Pollution: Joint production and averting expenditure measures of willingness to pay: do water expenditures really measure avoidance costs?, Nii Adote Abrahams, Bryan J. Hubbell and Jeffrey L. Jordan The economic benefits of surface water quality improvements in developing countries: a case study of Davao, Philippines, KyeongAe Choe, Dale Whittington and Donald T. Lauria Contingent valuation in Korean environmental planning: a pilot application to the protection of drinking water in Seoul, Seung-Jun Kwak and Clifford S. Russell Option prices of groundwater protection, Steven F. Edwards. Cost of Preventing Water Pollution: The on-farm costs of reducing groundwater pollution, Scott L. Johnson, Richard M. Adams and Gregory M. Perry Implications of alternative policies on nitrate contamination of groundwater, Manzoor E. Chowdhury and Ronald D. Lacewell Optimal spatial management of agricultural pollution, John Braden, Gary V. Johnson, Aziz Bouzaher and David Miltz. Part IV Transboundary Water Pollution Control: Trade's dynamic solutions to transboundary pollution, Linda Fernandez Transboundary water management: game-theoretic lessons for projects on the US-Mexico border, George B. Frisvold and Margriet F. Caswell Does trade promote environmental coordination?, Hilary Sigman. Part V Trends and Emerging Issues in Controlling Water Pollution: Informal regulation of industrial pollution in developing countries: evidence from Indonesia, Sheoli Pargal and David Wheeler Transaction costs of policies to reduce agricultural phosphorous pollution in the Minnesota river, Laura McCann and K. William Easter Designing environmental regulations with empirical microparameter distribution: the case of seawater intrusion, Gareth P. Green and David L. Sunding Groundwater management when water quality is endogenous, Catarina Roseta-Palma Index.

Optimization of Stormwater Filtration at the Urban/Watershed Interface

Abstract: Environmental pollution from cities is a major ecological problem attributed to contaminated runoff from nonpoint sources. The U.S. Environmental Protection Agency's guidance on implementation of total maximum daily loads (TMDL) does not adequately cover methods to improve waters impaired by nonpoint sources. To comply with TMDLs, cities may install filters in curb inlets, or use other Best Management Practices (BMPs). We tested 10 different filters and found their effectiveness in retaining pollutants ranged from 0 to >90%, depending on combinations of pollutant types (metals, pathogens, and total suspended sediments (TSS)) and filter materials. Hence, the decision to deploy filters into curb inlets must consider land use patterns associated with specific categories of pollutants generated within cities. We developed a geographic information system (GIS)-enabled model for estimating and mitigating emissions of pollutants from urban regions into watersheds. The model uses land use categories and pollutant...

Modeling Phosphorus in the Environment

Abstract: Basic Approaches Modeling Phosphorus Movement from Agriculture to Surface Waters, A. Sharpley Modeling Runoff and Erosion in Phosphorus Models, M.L. Wolfe Modeling Phosphorus in Runoff: Basic Approaches, M.L. Cabrera Basic Approaches to Modeling Phosphorus Leaching, N.O. Nelson and J.E. Parsons Phosphorus Transport in Streams: Processes and Modeling Considerations, B.E. Haggard and A.N. Sharpley Uncertainty Estimation in Phosphorus Models, K. Beven, T. Page, and M. McGechan Models Phosphorus Modeling in Soil and Water Assessment Tool (SWAT) Model, I. Chaubey, K.W. Migliaccio, C.H. Green, J.G. Arnold, and R. Srinivasan Modeling Phosphorus with Hydrologic Simulation Program-Fortran, D.E. Radcliffe and Z. Lin Phosphorus Modeling in the Annualized Agricultural Nonpoint Source Pollution (AnnAGNPS) Model, Y. Yuan, R.L. Bingner, and I. Chaubey Answers-2000: A Nonpoint Source Pollution Model for Water, Sediment, and Phosphorus Losses, F. Bouraoui and T.A. Dillaha Watershed Ecosystem Nutrient Dynamics - Phosphorus (WEND-P) Models, R.L. Kort, E.A. Cassell, and S.G. Aschmann Modeling Phosphorus with the Generalized Watershed Loading Functions (GWLF) Model, E.M. Schneiderman Phosphorus Indices, Best Management Practices, and Calibration Data Phosphorus Indices, J. Weld and A. Sharpley Challenges to Using and Implementing Phosphorus Indices in Nutrient Management Planning: an MMP Perspective, P. Hess, B. Eisenhauer, and B. Joern Quantifying the Effects of Phosphorus Control Best Management Practices, M.W. Gitau and T.L. Veith Small Watershed Data Collection to Support Phosphorus Modeling, D. Harmel and B. Haggard Modeling in the Future Suggestions to Improve Modeling of Phosphorus, D.E. Radcliffe and M.L. Cabrera Index

The impact of rainfall on fecal coliform bacteria in Bayou Dorcheat (North Louisiana).

Abstract: Fecal coliform bacteria are the most common pollutant in rivers and streams. In Louisiana, it has been reported that 37% of surveyed river miles, 31% of lakes, and 23% of estuarine water had some level of contamination. The objective of this research was to assess the effect of surface runoff amounts and rainfall amount parameters on fecal coliform bacterial densities in Bayou Dorcheat in Louisiana. Bayou Dorcheat has been designated by the Louisiana Department of Environmental Quality as a waterway that has uses such as primary contact recreation, secondary contact recreation, propagation of fish and wildlife, agriculture and as being an outstanding natural resource water. Samples from Bayou Dorcheat were collected monthly and analyzed for the presence of fecal coliforms. Fecal coliforms isolated from these samples were identified to the species level. The analysis of the bacterial levels was performed following standard test protocols as described in Standard Methods for the Examination of Water and Wastewater. Information regarding the rainfall amounts and surface runoff amounts for the selected years was retrieved from the Louisiana Office of State Climatology. It was found that a significant increase in the fecal coliform numbers may be associated with average rainfall amounts. Possible sources of elevated coliform counts could include sewage discharges from municipal treatment plants and septic tanks, storm water overflows, and runoff from pastures and range lands. It can be concluded that nonpoint source pollution that is carried by surface runoff has a significant effect on bacterial levels in water resources.

Pesticide retention in two small constructed wetlands: treating non-point source pollution from agriculture runoff

Abstract: Pesticide losses to the environment are undesirable because of possible environmental hazards. Loss of pesticides is likely in watersheds where pesticides are used. Small constructed wetlands (CWs)...

Vegetative Filter Strips for Nonpoint Source Pollution Control in Agriculture

Abstract: Author(s): Grismer, Mark E; O'geen, Anthony Toby; Lewis, David | Abstract: Irrigated orchards, vineyards, and row crops have high erosion rates. The vegetative filter strip (VFS) offers one way to control erosion rates and keep soil in the field rather than letting it be carried off site in drainage water.