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The Dolores River basin begins just north of the headwater of the San Juan River and <br />flows southwest to McPhee Reservoir, where it turns to the northwest and j oins the <br />Colorado River in Utah. The drainage area of approximately 4,6000 square miles in <br />Colorado, includes portions of Dolores, Mesa, Montezuma, Montrose, and San Miguel <br />Counties. Major tributaries include the West Fork of the Dolores, Lost Canyon Creek, <br />Disappointment Creek, West Paradox Creek, and the San Miguel River. Average flow of <br />the Dolores River is 680,000 acre-feet (1936-1954) at the USGS gage at Gateway. <br />The principal water use in both the San Juan and Dolores river basins is irrigation. The <br />average total irrigated acreage in the combined basins, according to the State's GIS data, <br />is approximately 254,100 acres for the period 1986 through 1990. In addition to direct <br />ditch diversions, there are thirteen major reservoirs. <br />Other water uses in the basin include diversions for mining operations, and diversions for <br />several towns. There are several exports from the San Juan River basin to the Rio <br />Grande basin, including the San Juan Chama project diversions, Treasure Pass Ditch, <br />Williams Creek Squaw Pass, Don La Font ditches 1 and 2, Pine-River Weminuche Pass, <br />and Weminuche diversion. Several small diversions from the San Juan to the Gunnison <br />River basin include Carbon Lake Ditch, Mineral Point Ditch, and Red Mountain Ditch. <br />The Leopard Creek Ditch diverts water from the Dolores basin to the Gunnison. <br />Terminology <br />The Colorado River is not only one of the most highly controlled rivers in the world, but <br />is also one of the most institutionally encompassed. A multitude of legal documents, <br />know collectively as the "Law of the River," effect and dictate its management and <br />operation. Major documents include: <br />Colorado River Compact-1922 <br />Boulder Canyon Project Act-1928 <br />California Limitation Act-1929 <br />California Seven Party Agreement-1931 <br />Mexican Water Treaty-1944 <br />Upper Colorado River Basin Compact-1948 <br />Colorado River Storage Project Act-1956 <br />United States Supreme Court Decree in Arizona vs. California-1964 <br />Colorado River Basin Project Act-1968 <br />Minute 242 of the International Boundary and Water Commission, <br />United States and Mexico-1973 <br />Colorado River Basin Salinity Control Act-1974, amended 1984 <br />The Colorado River System is defined in the Colorado River Compact of 1922 as "...that <br />portion of the Colorado River and its tributaries within the United States," whereas the <br />Colorado River Basin is defined as "...all of the drainage area of the Colorado River <br />System and all other territory within the United States of America to which water of the <br />culossapp Page 6 of 24 09/30/1999 <br />