The 141 square mile Rush Creek watershed begins in the Ansel Adams Wilderness at Mt. Lyell, over 13,000 feet in elevation. Upper Rush Creek flows into Grant Lake Reservoir. At the foot of Grant Lake, is the MGORD (Mono Gate One Return Ditch).
MGORD serves as the main source of water flowing down Lower Rush Creek, as well as the point of export for water being diverted to the Upper Owens River and eventually to the City of Los Angeles.
Lower, the section that was originally dewatered, now flows approximately 9 miles before reaching Mono Lake. The creek hosts rainbow and brown trout.