The casting ponds and the lodge were built by WPA workers in 1938 for the The Golden Gate Angling & Casting Club. You can visit the lodge in Golden Gate Park any day that there is a member present. The day I was there several members were practicing in the ponds, tying flies, and welcoming stray visitors with coffee and snacks.
Originally built as the terminal for Pan Am China Clipper seaplanes, the building also served as a welcome center for the 1939 Golden Gate International Exposition. The island itself, the terminal, and two hangars were WPA, PWA and San Francisco City projects. During World War II until 1997, the island was a US Navy base.