This article describes two probability sampling approaches to sampling water resources. In the first approach, a complete enumeration of eligible sample units (e.g. stream segments, water bodies, drainage basins) is performed using GIS or paper maps to create a list frame. A probability random sample is then selected from this frame. In the second approach, a two-stage sample is selected. In the first stage, area segments are selected

using a probability design, such as stratified sampling. Water resources contained in each segment are enumerated and labeled using field visits or aerial photographs. In a second stage, the water resource or related sampling units (e.g. stream segments, water bodies, measurement points) are selected in each of the segments. Examples of both approaches are presented, and their relative strengths and weaknesses are discussed.

Copies of preprints are available from the author upon request. Use the preprint number (top of right hand corner of the abstract) and make the request directly to the author, Iowa State University, Department of Statistics, Snedecor Hall, Ames, IA 50011-1210.