Action timeline

April 30, 2001 – In keeping with a legal settlement obtained by the Center, the U.S. Fish and Wildlife Service designated 23,903 acres in San Mateo and Santa Clara counties as critical habitat for the butterfly.

June 30, 1999 – The Center filed suit against the Service for failure to designate critical habitat for the Bay checkerspot butterfly, which had first been proposed in the 1980s but was subsequently withdrawn.