Upper Subbasin Overview
The Upper Subbasin drains approximately 143 square miles of mountainous terrain located above the confluence of the mainstem Van Duzen River with the Little Van Duzen River at river mile (RM) 48. Approximately half the land is located in each of Humboldt (73 sq. mi.) and Trinity (70 sq. mi.) counties. While the lower half of the subbsasin is primarily in private ownership, the upper half of the subbasin is mostly within the Six Rivers National Forest. Coniferous forest is the dominate type of vegetation, and timber production is the major land use. Several small rural developments and a few large private land ownerships are near the towns of Dinsmore and Mad River.
Eaton Falls located at RM 46, about two miles downstream of Dinsmore, is considered a natural barrier to upstream salmonid migrations, although there have been anecdotal reports of large salmonids (possibly steelhead) above the falls. The Van Duzen mainstem and its tributaries above Eaton Falls is populated by resident trout populations. Winter and summer run steelhead migrate to tributaries and upper reaches of the Little Van Duzen River. Passage of Chinook and coho to the Upper Subbasin is typically blocked at Salmon Falls in the Middle Subbasin, but reports of coho salmon have been made in Butte Creek and the Little Van Duzen River (Reynolds et al. 1981 and Decker and Fuller 1983).