《安全饮用水法》修正案的一个要素是井口保护计划。SDWA将井口保护区定义为“水井或井场周围的地表和地下区域，为公共供水系统供水，污染物可能通过这些区域流向并到达水井或井场。”划定井口保护区的标准可能包括距离、水位下降、行程时间和流动系统边界。当使用定量标准时，数学模拟模型通常是确定井口保护面积的唯一方法。本文介绍了井口保护区划定模型、模型选择过程、选择标准、信息来源和研究需求。必须根据井口区域涉及的问题类型选择模型: 例如，流动或溶质运输。选择标准包括模型的可用性、文档、用户支持、可用性、可靠性和模型的使用（即它的受欢迎程度）。

One element of the Safe Drinking Water Act amendments is a wellhead protection program. Wellhead protection areas are defined in the SDWA as "the surface and subsurface areas surrounding a water well or wellfield, supplying a public water system, through which contaminants are reasonably likely to move toward and reach water well or wellfield." Criteria on which wellhead protection areas may be delineated may include distance, drawdown, travel time, and flow system boundaries. Mathematical simulation models often provide the only method to determine the wellhead protection area when quantitative criteria are used. This paper describes models for wellhead protection area delineation, the model selection process, selection criteria, information sources, and research needs. The model must be chosen based on the type of problems involved in the wellhead area: for example, flow or solute transport. Selection criteria include availability of the model, documentation, user support, usability, reliability, and the use of the model (i.e., it's popularity).