Page 1

Effects on Grand Canyon National Park and Monument of proposed Lower Colorado River Project I. INTRODUCTION Among the components of Lower Colorado River developments considered herein are the proposed Bridge Canyon and Marble Canyon-Kanab Creek Tunnel. Each component is treated separately, since each will cause changes of a different nature. The proposed Bridge Canyon Reservoir and Kanab Tunnel individually and in combination would change the character of a particularly scenic length of wild river to something far less desirable from the National Park standpoint. The basic purpose of national parks and monuments, as stated in the Act of August 25, 1916, is to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations. In the Act to establish Grand Canyon National Park, approved February 26, 1919, there is, however, the following provision: That whenever consistent with the primary purposes of said park, the Secretary of the Interior is authorized to permit the utilization of areas therein which may be necessary for the development and maintenance of a Government reclamation project. To determine whether water control projects would be consistent with that purpose, it is necessary to ascertain and weigh the effects. II. BRIDGE CANYON DAM AND RESERVOIR This proposed damsite is located some 2.5 miles upstream from the head of Lake Mead and 237.5 miles downstream from Lees Ferry at an elevation of approximately 1200 feet. When filled, if constructed to an elevation of 1783 feet, as previously recommended by this Service, the reservoir will back water through the eastern portion of Lake Mead National Recreation Area and through Grand Canyon National Monument. If the dam is constructed to a height of 1877 feet, it would back water 13 miles into Grand Canyon National Park. A. Bridge Canyon Dam Constructed to Elevation 1783 Feet Although we realize that Grand Canyon National Monument was established with the recognition that at some future date a dam might be constructed at Bridge Canyon, it is important that we consider carefully the effects such a dam will create.Epson Perfection 4870 Photo, 400 dpi, 8 bit, 16,021,504 byte