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Atrazine is the most commonly used herbicide in the spring for pre-emergent weed control in the corn cropping area in the Midwestern United States. A frequent high level of herbicide concentrations in reservoirs is a great concern for public health and aquatic ecosystems. In this study, a two-dimensional hydrodynamics and toxic contaminant transport model was applied to Saylorville Reservoir, Iowa, USA. The model simulates physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. Model results were validated by measured temperatures and atrazine concentrations. Simulated flow velocities, water temperatures, and chemical concentrations demonstrated that the spatial variation of atrazine concentrations was largely affected by seasonal flow circulation patterns in the reservoir. In particular, the simulated fate and transport of atrazine showed the effect of flow circulation on spatial distribution of atrazine during summer months as the river flow formed an underflow within the reservoir and resulted in greater concentrations near the surface of the reservoir. Atrazine concentrations in the reservoir peaked around the end of May and early June. A thorough understanding of the fate and transport of atrazine in the reservoir can assist in developing operation and pollution prevention strategies with respect to timing, amount, and depth of withdrawal. The responses of atrazine transport to various boundary conditions provide useful information in assessing environmental impact of alternative upstream watershed management practices on the quality of reservoir water.

For community water providers, safeguarding source waters from contamination offers an additional barrier of protection and a potential means of avoiding in-plant treatment costs. Whether source water protection efforts are cost-effective relative to in-plant treatment requires hydrologic, geologic, and climatologic knowledge of source watersheds, as well as an understanding of how changes in source water quality affect treatment costs. Quantitative evidence on the latter relationship is limited. This study estimates separate hedonic cost functions for water systems that primarily use surface water sources and those that primarily use groundwater sources using a database of United States (US) Community Water Systems. Cost functions relate annual variable treatment cost to production, factor input prices, capital stock, and source water quality, as proxied by land use within various ex-ante defined contributing areas (i.e., surrounding land areas affecting source water quality). For surface water systems, a 1% increase in urban land relative to forestland is correlated with a 0.13% increase in annual variable treatment costs. In this analysis, the relationship between costs and agricultural land is not statistically significant. Conversely, for groundwater systems, a 1% increase in agricultural land relative to forestland is correlated with a 0.24% increase in costs, whereas in this analysis the relationship between costs and urban land is not statistically significant. The cost-effectiveness of forestland preservation, based on sample means, varies considerably with the size of the contributing area, with no clear indication as to whether preservation is more likely to be cost-effective for surface water or groundwater systems.

The World Health Organization has labeled the problem of arsenic contamination of groundwater in South Asia as “the largest mass poisoning in human history.” Various technical solutions to the problem fall into one of two broad categories: (i) cleaning contaminated water before human consumption and (ii) encouraging people to switch to less contaminated water sources. In this paper, we review research on the behavioral, social, political, and economic factors that determine the field-level effectiveness of the suite of technical solutions and the complexities that arise when scaling such solutions to reach large numbers of people. We highlight the conceptual links between arsenic-mitigation policy interventions and other development projects in Bangladesh and elsewhere, as analyzed by development economists, that can shed light on the key social and behavioral mechanisms at play. We conclude by identifying the most promising policy interventions to counter the arsenic crisis in Bangladesh. We support a national well-testing program combined with interventions that address the key market failures (affordability, coordination failures, and elite and political capture of public funds) that currently prevent more deep-well construction in Bangladesh.