What if a proposed development on private land is clearly incompatible with wild and scenic river designation, classification, or management objectives?

The government typically provides technical assistance to find ways to alleviate or mitigate the actual or potential threat(s). Purchasing a partial right (easement) or the property in fee title is usually the last resort. If an easement is purchased, the owner would sell certain development rights and receive a payment, yet retain title to the land.

Source
Interagency Wild & Scenic Rivers Council