Select the portion of the reach that you wish to measure (this may be the entire reach or riffles only). For
stream characterization, sample pools, runs and riffles in the same proportions as they occur in the study
reach. For other purposes, it may be more appropriate to use a random method, transects, or zig-zag pattern.
Most SOPs recommends collecting and measuring a minimum of 100 particles. Start at a selected point near the
downstream end of the reach. Starting on the shoreline, take a step into the stream. Averting your gaze,
pick up the first particle touched by the tip of your index finger at the toe of your wader. Measure the
intermediate axis (neither the longest nor shortest of the three mutually perpendicular sides of each
particle picked up). Continue across the channel in an upstream direction towards the opposite bank and
repeat the process, continuing to pick up particles until you have the requisite number of measurements.
Measure embedded particles or those too large to be moved in place.