Price James I, Heberling Matthew T
Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268.
Ecol Econ. 2018 Sep 3;151:195-209. doi: 10.1016/j.ecolecon.2018.04.014.
Watershed protection, and associated water quality improvements, has received considerable attention as a means for mitigating health risks and avoiding expenditures at drinking water treatment plants (DWTPs). This study reviews the literature linking source water quality to DWTP expenditures. For each study, we report information on the modeling approach, data structure, definition of treatment costs and water quality, and statistical methods. We then extract elasticities indicating the percentage change in drinking water treatment costs resulting from a 1% change in water quality. Forty-six elasticities are obtained for various water quality parameters, such as turbidity, total organic carbon (TOC), nitrogen, sediment loading, and phosphorus loading. An additional 29 elasticities are obtained for land use classification (e.g., forest, agricultural, urban), which often proxy source water quality. Findings indicate relatively large ranges in the estimated elasticities of most parameters and land use classifications. However, average elasticities are smaller and ranges typically narrower for studies that incorporated control variables consistent with economic theory in their models. We discuss the implications of these findings for a DWTP's incentive to engage in source water protection and highlight gaps in the literature.
流域保护以及相关的水质改善，作为减轻健康风险和避免饮用水处理厂（DWTPs）支出的一种手段，已受到广泛关注。本研究回顾了将源水质量与饮用水处理厂支出联系起来的文献。对于每项研究，我们报告有关建模方法、数据结构、处理成本和水质的定义以及统计方法的信息。然后，我们提取弹性系数，该系数表示水质变化1%所导致的饮用水处理成本的百分比变化。针对各种水质参数，如浊度、总有机碳（TOC）、氮、沉积物负荷和磷负荷，获得了46个弹性系数。对于通常代表源水质量的土地利用分类（如森林、农业、城市），又获得了29个弹性系数。研究结果表明，大多数参数和土地利用分类的估计弹性系数范围相对较大。然而，对于在模型中纳入了与经济理论一致的控制变量的研究，平均弹性系数较小且范围通常较窄。我们讨论了这些研究结果对饮用水处理厂进行源水保护激励措施的影响，并突出了文献中的差距。
