Approaches for Site Selection for Monitoring and Assessment

Selection of sampling location is an integral part of any research activity to monitor, assess, and diagnose ecological condition. A random site selection approach results in an unbiased assessment of resource conditions, however multiple factors influence the selection of an approach for determining sampling locations: availability of resources/personnel for sampling, limited access due to landowner permission, the size and type of the resource under study, (e.g., small streams, large rivers, wetlands), field sampling methods, and the goals of the research project. EERD is participating in research to evaluate the potential bias of assessments associated with different site selection approaches. Two research projects are underway, one in wadeable streams (Wisconsin) and one in great rivers (Ohio River). Each of these research efforts compares a purely random site selection with a non-random site selection and quantifies the level of bias associated with the non-random approach. Results of this research will provide valuable information to aid in balancing potential bias associated with the site selection approach, the goals of the research, and the cost and effort associated with a purely random sampling design.

The objective of this research is to quantify the bias associated with non-random sampling designs as compared to random sampling designs in the assessment of wadeable streams and great rivers.

Comparison of Random and Systematic Site Selection for Assessing Attainment of Aquatic Life Uses in Segments of the Ohio River. This report describes research based on existing data sets to develop a random sampling design for the Ohio River. The resulting approach provides known levels of confidence in condition estimates of the river while minimizing the yearly level of effort required.

Report on the Regional Environmental Monitoring and Assessment Program Study of Wadeable Streams in the Driftless Area Ecoregion in Western Wisconsin (PDF) (81pp, 2MB) - EPA 600/R-06/165 November 2006. This report describes the results of a REMAP agreement awarded to the Wisconsin Department of Natural Resources (WDNR) to compare random and modified-random sampling designs.