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Green River/Great Divide Basin


Green River/Great Divide Basin (Overview) HUC# 140401, 140402

Basin Geography:

The Green River originates in the Wind River Range and Bridger-Teton National Forest of west-central Wyoming and flows southward into Utah. Moist mountainous terrain in the north and west of the basin produce perennial streamflow, while dry high plateaus in the south and east exhibit ephemeral streams. Tributaries to the Green include the New Fork, Big Sandy and Blacks Fork. On the Green River, Fontenelle and Flaming Gorge Reservoirs have a capacity of over 4 million acre-ft and regulate flows on this major tributary of the Colorado River System. The Great Divide portion of this hydrologic unit is a closed basin of 3,959 square miles to the east.

The coal and trona minerals industries as well as gas and oil development are prevalent in the basin. Concerns over groundwater contamination from industrial uses and natural fluoride deposits exist. Industry is a principal user of the structural aquifers underlying the basin. Salt and sediment loading of surface flows due to agricultural water use in the basin are a water quality concern. Threatened Colorado River Cutthroat Trout species are found in the Green River.

Relevant Compacts and Decrees:

The "Law of the River" for the Colorado is a combination of interstate compacts, court decrees, statues and international treaties. The 1922 Colorado River Compact established the upper and lower Colorado River sub-basins, of which Wyoming is part of the upper basin. A 1948 upper basin compact between Colorado, Utah, New Mexico and Wyoming established Wyoming's share as 14% of the upper basin allocation. Actual water flows have been revised since 1922. Currently Wyoming's annual allotment is 833,000 acre-ft, for use in the Little Snake and Green River basins. This allocation is not fully used in the basins, resulting in approximately 455,000 acre-ft of water flowing out of Wyoming unappropriated. This is of great concern given that downstream states such as California and Nevada thirst for additional water supplies. The Green River basin is a high priority region in Wyoming water planning initiatives.


Jacobs, James & Donald Brosz. 1993. Wyoming's Water Resources. University of Wyoming Cooperative Extension Bulletin B-969, Laramie, WY. pp 6.

US Geological Survey. 1985. National Water Summary-Wyoming: Surface Water Resources, Water Supply Paper 2300. pp. 493-8.

US Geological Survey. 1990. National Water Summary-Wyoming: Stream Water Quality, Water Supply Paper 2400. pp. 573.

US Geological Survey. 1986. National Water Summary-Wyoming: Ground-water Quality, Water Supply Paper 2325. pp. 541.

Wyoming Water Development Commission & Wyoming State Engineer's Office. 1996. Wyoming Water Planning: A Report for Updating the Process. Cheyenne, WY. pp.17-20

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