Headwaters Forest Act of 1994 - Extends the boundaries of the Six Rivers National Forest, California, to include certain lands to be referred to as the Six Rivers National Forest Addition.

Authorizes the Secretary of Agriculture to acquire land within the extended boundaries by donation, purchase, or exchange for other excess or surplus Federal lands. Directs the Secretary to develop and implement a land acquisition plan giving priority to the acquisition of lands for the Headwaters Forest Wilderness.

Designates the Headwaters Forest Wilderness lands, upon acquisition, as a component of the National Wilderness Preservation System.

Requires the Secretary to develop a comprehensive management plan prescribing measures for the preservation of the existing old growth redwood ecosystems in the Addition, including: (1) a prohibition on timber sales from lands within the old growth redwood groves; and (2) measures to restore lands affected by previous timber harvests to mitigate watershed degradation and impairment of habitat for the marbled murrelet, spotted owl, native salmon stocks, and other old-growth forest dependent species.

Sets forth provisions regarding payments to local governments in lieu of taxes for lands acquired under this Act.

Directs the Secretary to study specified lands in the Addition, analyzing the area's potential for addition to the Headwaters Forest and identifying the area's natural resources.

Authorizes appropriations.