intrastate waters:
“a. Which are or would be used as habitat by birds protected by Migratory Bird Treaties; or
“b. Which are or would be used as habitat by other migratory birds which cross state lines; or
“c. Which are or would be used as habitat for endangered species; or
“d. Used to irrigate crops sold in interstate commerce.” 51 Fed. Reg. 41217. [***583]
This last promulgation has been dubbed the “Migratory Bird Rule.” 1