September 20, 2004 – The Center sued to compel the U. S. Fish and Wildlife Service to respond to the petition.
May 3, 2006 – The Service denied protection to the roundtail chub and made the headwater chub a candidate for protection.
September 7, 2006 – After the Service denied both species protection in May, the Center sued again to overturn the denial.
July 7, 2009 – The Service announced that the roundtail chub in the lower Colorado River warranted protection as an endangered species, but that such protection was precluded by work on listing other species. The roundtail chub thus joined 252 other species as a “candidate” for protection.
July 12, 2011 – The Center reached a landmark agreement with the Fish and Wildlife Service compelling the agency to move forward in the protection process for 757 species, including the roundtail and headwater chubs.