S1_11-15-04

• Basin: Statewide
• Title: SWSI Phase 1 Report - Section 1 Introduction
• Date: 11/15/2004
• Author: CWCB
• SWSI - Doc Type: Final Report

Section 1
Introduction
1.2 Background on Colorado
Water Resources
Eight major river basins drain Colorado, all with their
headwaters in the high mountains of the Continental
Divide. Rivers east of the Divide flow ultimately into the
Gulf of Mexico, while the western rivers find their way,
via the Colorado River, to the Gulf of California and the
Pacific Ocean. The interrelationship of these eight basins
is described below in the context of four major river
systems originating in Colorado.
1.2.1 Colorado River, Gunnison River,
Yampa/White/Green Rivers, and
Dolores/San Juan/San Miguel
Rivers
The Colorado River system drains over one-third of the
state's area. Originating in the north central mountains,
the main stream of the Colorado flows southwesterly and
is met at Grand Junction by the Gunnison River before
flowing west into Utah. The Yampa and the White move
westward across the northwest quadrant of the state to
the Utah border
where they join
the Green,
another tributary
of the Colorado.
The San Miguel
and the Dolores
begin near the
southwestern
corner and travel
north along the western border and into Utah. The San
Juan and its tributaries collect the water in the
southernmost regions west of the Divide and carry it into
New Mexico.
Less than 20 percent of the entire Colorado River Basin lies
inside Colorado, but about 75 percent of the water in the
entire river basin originates in the state. Much of this water
has been allocated by compact or treaty. Transmountain
diversions of these supplies also occur to other parts of the
Colorado River Basin states. Over 60 percent of the land in
this basin is federal land. In Colorado, transbasin diversions
account for about 5 percent of the total supply, or about
500,000 acre-feet (AF).
1.2.2 South Platte River, Republican
Riv~r, and Narth Platte River
The South Platte River drains the most populous section
of the state and serves the area with the greatest
concentration of
irrigated
agricultural lands.
Its waters originate
chiefly in the
mountain streams
along the north half
of the Front Range
of the Eastern
Slope. The main
stream moves north, then east, and meets the North
Platte in southwestern Nebraska. This basin comprises
about 20 percent of the state's land area.
Water supply in the South Platte Basin is supplemented
by transbasin diversions from the Colorado River Basin
and to a lesser degree from the Arkansas River Basin.
Here, new industry and rapidly expanding urbanized
areas compete with agriculture for the same supplies of
water.
While both rural and urban centers are growing, this
growth does not represent agricultural growth since the
trend is toward urbanization. Less than one-third of the
land in this basin is public land.
The Republican River Basin drains approximately
7 percent of the state's area in northeastern Colorado.
The area is predominantly agricultural. Water supplies in
the basin come from the Republican River and its
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Figure 1-1
Co/orado's Eight Major River Basins
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