A PEBBLE COUNT PROCEDURE FOR ASSESSING WATERSHED CUMULATIVE EFFECTS

Land management activities can result in the delivery of fine sediment to streams. Over time, such delivery can lead to cumulative impacts t o the aquatic ecosystem. Because numerous laws require Federal land ma nagers to analyze watershed cumulative effects, field personnel need s imple 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 l ong using a zig-zag pebble count procedure that crosses all habitat fe atures within a stream channel. The approach accommodates reference (u nimpacted) and study (impacted) reaches so that impact comparisons can be made. Case studies show how the procedure is applied.