Congress has specified in some Wild and Scenic River designations, that rivers are to be administered by the Secretary of the Interior through the NPS in partnership with local governments, councils, and non-governmental organizations, generally through the use of cooperative agreements. In these Partnership Wild and Scenic Rivers communities protect their own outstanding rivers and river-related resources through a collaborative approach. See a list of Partnership Wild and Scenic River Contacts.
This approach has been very successful. Read the whole document - '20 Years of Success Protecting Nationally Significant River Resources through Locally Based Partnerships' - which details some of the past 20 years of achievements using this model.