A pebble count procedure for assessing watershed cumulative effects

Land mangement activities can result in the delivery of fine sediment to streams. Over time, such delivery can lead to cumulative impacts to the aquactic ecosystem. Because numerous laws require Federal land managers to analyze watershed cumulative effects, field personnel need simple monitoring procedures that can be used directly and consistently. One approach to such monitoring is described. The approach involves sampling a longitudinal reach of stream channel several hundred feet long using a zig-zag pebble count procedure that crosses all habitat features within a stream channel. The approach accomodates reference (unimpacted) and study (impacted) reaches so that impact comparisons can be made. Case studies show how the procedure is applied.