The Cerro Grande has been called the biggest fire in New Mexico history. The Cerro Grande blaze raged across the hillsides above Los Alamos National Laboratory, then, driven by high winds, the fire raced through the Laboratory and the Los Alamos town site. The fire destroyed over 250 dwellings and left more than 400 families homeless. The human and environmental consequences are staggering with much still to be learned. This presentation will begin with a brief description of the fire followed by a discussion of the rehabilitation efforts and the broader environmental consequences of the fire. One of the consequences of forest fires is the potential for runoff from precipitation to increase two to three orders of magnitude compared to pre-fire flows. The implications for the Cerro Grande are many. Los Alamos National Laboratory occupies 43 square miles approximately in the center of the Pajarito Plateau. Indian Pueblos, Cochiti Reservoir and the city of Albuquerque lie downstream of the Laboratory. The Cerro Grande fire has emphasized the importance of considering environmental consequences and the protection of water quality on the watershed scale. Sediments contaminated with low levels of radioactivity are present in several of the canyons traversing the Lab. Several nuclear facilities are present in the canyon bottoms. These canyons have their headwaters in the severely burned Forest Service lands above the Lab and drain across an Indian Pueblo before reaching the Rio Grande. Rehabilitation efforts to minimize the impacts of the Cerro Grande fire ranged from contour felled trees and seeding to the construction of a ninety-foot high flood retention structure. The Laboratory is intensively monitoring runoff to evaluate post fire effects. Observations of the environmental impacts, including increased levels of radionuclides and cyanide, will be discussed.