How does wild and scenic river designation affect timber management activities on non-federal lands inside the corridor?

Timber management activities on non-federal lands within wild and scenic river corridors are guided by state and local authorities. Under the Wild & Scenic Rivers Act, the only way the federal government can restrict private timber management is through purchase of timber rights (in easement or fee title). The river manager may provide technical assistance and/or work with state/local governments to protect river values.

Source
Interagency Wild & Scenic Rivers Council