The effect of logging and roadbuilding on erosion and sedimentation are analyzed by comparing the North Fork and South Fork of Caspar Creek, in northern California. Increased sediment production during the 4 years after road construction, was 326 cu yd/sq mi/yr-80 percent greater than that predicted by the predisturbance regression analysis. The average sediment load during the 3 years of logging increased by 957 cu yd/sq mi/yr-275 percent greater than the predicted values. Although the erosion or sediment increases do not appear to be degrading site quality, average turbidity levels in the South Fork exceeded water quality standards.