Strategic Planning and Resource Assessment

Forest Service 2003 Success Stories

Success Stories: Assessing the Impacts of Forest Harvest Practices in the Caspar Creek Experimental Watershed

Research at the Pacific Southwest Research Station in collaboration with the California Department of Forestry and Fire Protection is providing information on the extent and nature of hydrologic, erosion, and sedimentation impacts of logging operations on watersheds in northern California . Additional partners include UC Berkeley, Cal Poly San Luis Obispo, UC Davis, and Humboldt State University . Results and empirical models from this research are being applied by the California Board of Forestry and private industry to evaluate the effectiveness of forest practice rules in northern California . In addition, sampling methods developed at Caspar Creek for measuring sediment loads are being adopted for water quality monitoring by state and federal agencies, private industry, and community watershed groups as forest impacts come under increasing public scrutiny.

In 1962, scientists at the Pacific Southwest Research Station, Redwood Sciences Laboratory initiated a "paired watershed" experiment in the Caspar Creek Experimental Watershed on the Jackson Demonstration State Forest near Fort Bragg , California . Researchers recorded changes in streamflow and sedimentation before and after road-building and selective tractor logging in the South Fork of Caspar Creek. For one year after road-building, suspended loads increased 335 percent over that predicted from pretreatment conditions, and, for five years after logging, an increase of 354 percent was reported. Although early season peak flows increased by 300 percent after logging, no changes were detected in large storm flows.

Changing forest practices led researchers to initiate a new phase of studies in the 1980s. In the North Fork, 13 new gaging stations were installed and several sub-watersheds were subsequently clear-cut, as was a common practice in redwood stands at that time. However, because logs were mostly yarded to the ridges by cable, there was much less ground disturbance, and greater stream protection. Nevertheless, suspended sediment increases as high as 238 percent were detected in clear-cut tributaries after logging. In contrast to the earlier study, peak flow increases were detected in large storms as well as small ones, and the finding was attributed to an improved study design and instrumentation.

North Fork Casper Creek ARF Station Stormflow

South Fork Casper Creek POR Station, 2002

USDA Forest Service - Strategic Planning and Resource Assessment
Last Modified: Tuesday, 18 May 2004 at 11:33:12 EDT