October 13, 1998 – The U.S. Fish and Wildlife Service listed Munz's onion as endangered.
November 15, 2001 – The Center and the California Native Plant society filed suit against the Service for its failure to designate critical habitat for eight plant species, including Munz's onion.
June 4, 2004 – The Service proposed to designate 227 acres of critical habitat for Munz's onion.
June 7, 2005 – The Service published a final rule designating 176 acres for Munz's onion, almost a 25-percent cut
August 28. 2007 – The Center filed a notice of intent to sue the Bush administration for wrongful Endangered Species Act decisions affecting 55 species, including the designation of insufficient critical habitat for Munz's onion.
October 2, 2008 – The Center sued the Bush administration over six politically tainted Endangered Species Act decisions, including the Munz's onion's insufficient critical habitat designation.
May 5, 2016 – The Center and allies filed a lawsuit challenging Riverside County's approval of a plan to trade away more than 40 acres of important habitat for endangered plants, including San Diego ambrosia, to a private developer.