Colorado State Water Plan 1974 ‎(Phase I)‎

• Year: 1974
• Title: Colorado State Water Plan
• CWCB Section: Agency-wide
• Publications - Doc Type: Historical

General Description of the Environment
River, a third tributary to the Missouri River System, originates in the plains of
eastern Colorado. Major tributaries of the Colorado River System also originating
in Colorado include the San Juan, Dolores, Gunnison, White, and Yampa Rivers.
The basins of these major streams are shown on exhibit 1.1. The distribution of
the State's area (104,247 mi2) is shown by major drainage basins in table 2.1.
Table 2.1--Drainage basins of Colorado
River basin Square miles Percent of State
Arkansas 28,297 27
Colorado 38,542 37
Missouri 29,877 29
Rio Grande 7, 531 7
State total 104,247 100
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GEOLOGY
The Southern Rocky Mountain Province is a rugged zone of north-south
trending mountain ranges which form a continuous belt across central Colorado.
The typical mountains have cores of igneous and metamorphic rocks. They
originated by repeated uplifts of igneous rocks through the sedimentary rocks
that were once continuous across this mountainous region. The uplifted rocks
have been modified through the ages by glaciation and other forces of erosion.
Steeply dipping sedimentaries still flank the mountains and extend eastward
under the Great Plains and westward under the Colorado Plateau.
The repeated uplifts combined with erosion have removed nearly all
evidence of the sedimentaries from the mountain province. Exceptions occur
within the South, Middle, and North Parks and the San Luis Valley which are
structural basins resulting from being inactive during the periods of uplift.
Sedimentary rocks, mainly shale, sandstone, and siltstone, are found in the
three parks while the San Luis Valley has been filled with alluvium (sand, gravel,
and clay).
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2.2