1999 – The Center first petitioned the National Marine Fisheries Service to list the Cook Inlet beluga whale under the Endangered Species Act.
May 8, 2000 – The Center, along with a coalition of environmental groups, filed a lawsuit to force the Fisheries Service to take action on the listing petition. In response, the Fisheries Service declared the Cook Inlet beluga population a “depleted species” under the Marine Mammal Protection Act.
April 20, 2006 – The Center joined Cook Inletkeeper and other conservation groups to petition the Fisheries Service a second time to list the Cook Inlet beluga whale under the Endangered Species Act.
April 20, 2007 – The Fisheries Service proposed listing the Cook Inlet beluga whale as an endangered species, and the agency received more than 150,000 public comments in support of listing. A final listing decision was scheduled to be made by April 2008.
April 22, 2008 – The Fisheries Service extended the deadline for its final listing decision to October 2008.
June 30, 2008 – The Center and four allies filed suit against the Fisheries Service for its illegal delay in listing the Cook Inlet beluga whale.
October 17, 2008 – The Fisheries Service declared it would list the Cook Inlet beluga as endangered under the Endangered Species Act but failed to designate critical habitat.
January 14, 2009 – Alaska Governor Sarah Palin led her state in filing a notice of intent to sue to overturn the beluga's federal protections.
April 13, 2009 – Six months after it legally should have designated critical habitat for the whale, the Fisheries Service took the first steps toward doing so, requesting public comment on areas to be protected. A critical habitat rule was slated to be made by October 22, 2009.
December 1, 2009 – After the Center filed a notice of intent to sue in October, the Fisheries Service proposed to protect more than 3,000 square miles, or almost 2 million acres, of critical habitat for the Cook Inlet beluga.
August 4, 2010 – A coalition of conservation groups, including the Center, moved to intervene in a case filed by the state of Alaska against the National Marine Fisheries Service to remove protections for the Cook Inlet beluga whale.
April 8, 2011 – The National Marine Fisheries Service designated 1,928,320 acres (3,013 square miles) of critical habitat in upper Cook Inlet for the Cook Inlet beluga under the Endangered Species Act.
November 21, 2011 – A federal judge rejected the state of Alaska's 2010 lawsuit that tried to strip Endangered Species Act protections for Cook Inlet beluga whales.
May 15, 2012 – The Center for Biological Diversity, Natural Resources Defense Council, Native Village of Chickaloon and Center for Water Advocacy filed a lawsuit challenging a permit issued by the National Marine Fisheries Service to Apache Alaska Corporation to allow oil and gas exploration threatening belugas in Alaska's Cook Inlet.
May 30, 2013 – A U.S. district judge ruled that the federal government's decision to allow oil and gas exploration in Alaska's Cook Inlet violated three federal statutes, including the Marine Mammal Protection Act and Endangered Species Act.
January 4, 2017 – The National Marine Fisheries Service published a recovery plan for the Cook Inlet beluga whale to serve as a detailed blueprint to guide efforts to recover this federally endangered species.
February 2017 – The operator of a leaking natural gas pipeline in Cook Inlet was warned by federal regulators to improve maintenance of its gas pipelines, which were acknowledged as a potantial threat endangered Cook Inlet beluga whales. One pipeline had been leaking since December of the previous year without its owner, Hilcorp Alaska, stepping in to simply shut it off.
April 1, 2017 – Hilcorp Alaska reported yet another leak threatening these belugas, this time from an oil pipeline in Alaska's Cook Inlet. south of Tyonek, in critical habitat for the whales.