Water Quality and Hydrology

Investigators: Arne Skaugset and Nic Zegre, OSU Forest Engineering Department

Hinkle Creek is located 25 miles northeast of Roseburg , Oregon in the foothills of the Cascades. The watershed is almost wholly owned by Roseburg Forest Products and supports a stand of 55-year old, harvest-regenerated Douglas fir. The forest stand is typical of the kind of forests and forestland currently owned and managed by private, industrial, timberland owners in western Oregon . Thus, it represents an excellent place to test the efficacy of contemporary forest practices with regard to impacts on water quality.

The Hinkle Creek Paired Watershed Study is a nested, paired watershed study. The main study watershed has an area of 5,000 acres evenly divided into the North and South Forks of Hinkle Creek. Roseburg Forest Products has set the North Fork aside for 10 years to act as a control. The South Fork will serve as the treated watershed in the paired watershed study. Within the North Fork and South Fork watersheds, six headwater watersheds, or small watersheds drained by perennial non-fish-bearing streams, will also be established as a paired watershed study. Two of these watersheds are in the North Fork and will act as controls. Four small watersheds are located in the South Fork and will be treated.

Discharge, suspended sediment, and temperature will be measured on each of the small perennial, non-fish-bearing streams as well as at the mouths of the North and South Forks of Hinkle Creek. For the four small, perennial, non-fish-bearing watersheds being treated, the streams will be monitored at the downstream end of proposed harvest units. For the two small control watersheds, the measurements will be made at an accessible location in watershed areas comparable to the treated small watersheds.

The treatment planned for the South Fork of Hinkle Creek is intensive forest management activities using contemporary forest practices as prescribed by the Oregon Forest Practice Act rules. The first entry of harvesting activities for the South Fork of Hinkle Creek is scheduled for late 2005. The timber will be harvested in four harvest units located, at least partly, in the four study watersheds directly upstream of the stream gauging installations. For all four of the harvest units, the timber will be harvested using current forest practices that will include merchantable timber adjacent to the perennial, non-fish-bearing streams. No formal buffer strips will be prescribed.

The results presented in this paper represent findings for the first year of hydrology and sediment collection and three years of stream temperature.