For practitioners, the hundreds of stream assessment protocols and forms now in use across the U.S. create a confusing and variable matrix, much of it ‘qualititative’ and much of it increasingly ‘opinion-based.’  Even the widely used Rosgen Stream Classification System, taught through short courses and promoted by some in government, produces varying classifications most of the time according to peer-reviewed study.

As far back as 2008, studies including those published in the Journal of American Water Resources, have attempted to discover whether stream measurements and processes implemented by different observers yield consistent consistent assessment. One study, titled “The Role of Observer Variation in Determining Rosgen Stream Types in Northeastern Oregon Mountain Streams,” showed that in 66% of the evaluations, crews generated different results for the same stream.

Most discrepancies identified in this specific study could be attributed to measurements performed for the calculation of a characteristic called the “entrenchment ratio.”  The differences in the assessment of this value, described as “inherently uncertain” by the study authors, often resulted in different determination of primary stream types.

Despite the Rosgen Classification system’s widespread use and popularity, studies like this one demonstrate that even some of the measurements within assessment protocols, where ill-defined or ambiguous, may cause highly variable results within the same streams among different practitioners. 

For more than two decades now, Trout Headwaters and others working to heal our damaged streams and rivers have been calling for science-based, repeatable and field-data-driven assessment processes and protocols.  In fact, Trout Headwaters formed a start-up years ago, which has helped to build and deploy commercial hardware/software systems for government and industry intended to address exactly these issues  for practitioners.

The past few years have seen an explosion of new and mostly untested district, state and regional stream assessment protocols.  Directing action based on these outputs threatens to take us away from true science-based decision making. And the general lack of repeatability for these protocols by different technicians will make effective project monitoring nearly impossible.