Study to investigate extrapolation limits of stream condition scores

SCCWRP and the California Department of Fish and Wildlife in August will launch a study seeking to clarify how far stream condition scores calculated for a single stream site can be extrapolated upstream and downstream of the site.

Stream managers across California have begun using a new scoring tool called the California Stream Condition Index to evaluate the ecological health of wadeable streams statewide; however, users lack guidance on how far they can extrapolate scores beyond the individual sites where the scores have been calculated.

Understanding the spatial representativeness of stream condition scores is critically important because stream managers don’t have the resources to conduct bioassessment work along every kilometer of every stream in California. A stream bioassessment is typically conducted along a site that spans just 150 meters.

The ability to extrapolate California Stream Condition Index scores will become increasingly important as the scoring tool is integrated into regulatory and stream management programs statewide.

The study, expected to be completed by the end of 2016, will use sophisticated statistical analyses and the consensus of an expert review panel to arrive at recommended extrapolation limits.