WSP05382

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/1/1975
• Title: The Natural Salinity of the Colorado River
• Water Supply Pro - Doc Type: Publication

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Figure 9. Mancos sbale at Chimney Rock, New Mexico.

Tertiary formations in the Green River Basin, particularly the shale
tongues of the Green River Formation, not only impart the pale
greenish-gray color to the river that first bore the name, but they are
probably primarily responsible for the salt load that marks Big Sandy
Creek particularly, a major degrader of river water quality. Big Sandy
Creek travels some 30 miles across these shales after collecting its waters
on the Wind River Mountains. The salt seeps identified as the major
sources of contamination could be localized by small faults that guide
concentrations of groundwater through the shales. Green River from the
junction of Big Sandy Creek continues to the Flaming Gorge Reservoir
largely in Laney shale tongue of the Green River Formation. Along the
Big Sandy, tuff beds in the Bridger Formation probably contribute
significant amounts of salt to the stream.

The Price River is now thought to be the third largest contributor of
salt to the Colorado. It begins in the Roan Cliffs of Green River shale
near Soldiers Summit, and its upper course follows the outcrop belt of
the red shaley Colton Formation across Emmas Park until it drops down
through the Book Cliffs to Castle Gate. Here it begins its passage across
the Mancos shale to the Green River.

Although most of the salt load of the Price River is undoubtedly a
diffuse load picked up by overland runoff from rains and melting snows

9

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