OCR Text |
Show Canyon, water stored in Navajo Reservoir above elevation 5,945 feet will be withdrawn after September 1 of each year. However, the rate of withdrawal shall not exceed 2 feet per day when the water surface is above elevation 5,990 feet nor 1 foot per day when the water surface is below elevations 5,990 feet, "d. After the reservoir water surface is lowered to elevation 5,945 feet, the releases from the reservoir will be according to the requirements of paragraphs 2 and 3a." Lower Basin Hydrology A tour of the Lower Colorado River Basin a few years ago revealed the need to know considerably more about the hydrology of that Basin than was generally known at the time. Therefore, the Commission's staff has established a continuing study of the Lower Basin in order that the Commission may be more fully advised about the river system as a whole. For example, in its office the Commission staff is: 1. Maintaining a current "water log" of the Colorado River in the Lower Basin. Streamflow records beginning with 1951 have been tabulated for all measuring stations on the mainstream of the Colorado River and at the mouths of tributaries below Lee Ferry. These tables aid in locating reaches of the river that gain or lose water. Unusual changes in quantities of water used are readily ascertainable. 2. Maintaining a "water log" of the Colorado River below Imperial Dam. This log is a refinement of the tables mentioned above. The reach of the river below Imperial Dam to the Mexican boundary is the reach of greatest diversion of water from the Colorado River. All uses of water, losses, and return flows are indicated on this log. 3. Keeping a current "water log" of the Colorado River in the limitrophe section. This record is intended to show the amount oi unmeasured water that enters the Colorado River below the northern boundary and above the southern boundary between the United States and Mexico. 4. Keeping records of Lower Basin mainstream depletions. This tabulation lists all of the depletions to the Colorado River, computed by an inflow-outflow procedure, beginning with 1957, for certain specified reaches of the river. 26 |