Reach Monitoring


by Emma Hurley, Scientific Technician


Now that the rain has started its time to enter data from the fall field season. Late summer into fall we were in REACH MONITORING mode. We have three project reaches that we check every year to add to our baseline data of the watershed. This data also helps us track how our restoration projects have made a difference. These three project REACHES are all around 1,000 feet long and located on smaller tributaries. The surveys we do in each reach includes thalweg elevations surveys, cross-section elevations, riparian vegetation, canopy density, substrate size and composition, water and air temperature, and instream large wood abundance.

PEBBLE COUNTS (in photo). These are just what they sound like: counting and measuring rocks. We do four pebble counts per reach at the same locations each year. Pebble counts give us an average substrate size for the stream. This is helpful because we can track erosion trends and track new erosion events. Pebble counts can also inform Salmonid habitat. We do our counts in areas that could be spawning habitat and salmon are picky with their substrate! How to do them: take a step, put a figure down without looking, first rock you touch you measure- repeat 100 times! That is how we get an average: from a random sample. We conduct our pebble counts in roughly the same locations each year, which is the first riffle below our three cross-sections and our reach end.