Conversation so far:
What did Olmsted help conserve ?
In the 1880s he was active in efforts to conserve the natural wonders of Niagara Falls, threatened with industrialization by the building of electrical power plants.
What is another region he helped conserve ?
designate Yosemite Valley and Mariposa Big Tree Grove as public reserves.

Question: Did he join any association for conservation ?
Self-contained rewrite: Did Frederick Law Olmsted join any association for conservation ?