The Colorado: a Stressed
Exotic River
Collected and Organized by:
Joe Naumann, UMSL
An extremely helpful resource:
Physical Environment: An Introduction
to Physical Geography
By Michael Ritter
Exotic River
An exotic stream is one whose
headwaters lie in a humid region, and
flows through an arid environment
Examples:
Nile River
Colorado River
Colorado River Watershed
HEADWATERS
The Colorado River's headwaters are
located high in Rocky Mountain
National Park, just west of the
Continental Divide. After leaving
Rocky Mountain National Park the
river follows the Kewuneeche Valley
and is then dammed to create Grand
Lake and Shadow Mountain
Reservoir.
Headwaters in the Rockies
The Colorado
River as a
babbling brook
LOWER COURSE
The lower course of the river, which
forms the border between Baja
California and Sonora, is essentially a
trickle or a dry stream today due to use
of the river as Imperial Valley's
irrigation source. Prior to the mid 20th
century, the Colorado River Delta
provided a rich estuarine marshland
that is now essentially desiccated, but
nonetheless is an important ecological
resource.
Problem of Reduced Flow &
Desiccated Delta Region
Recent years of reduced annual
snowfall in the Rocky Mountains
(could this be related to global
warming?)
Increasing demand for water by
growing cities in California, Nevada,
Utah, Colorado, & Arizona
Increasing demand for water for
irrigated agriculture
Pictorial Evidence of Human
Impact on the River Basin
Years of drought in the Rocky
Mountains with Forest & Grassland
Fires
Colorado Cattleman with a Dry
Pond – Result of Drought
A farmer who
planted
sorghum –
drought victim
on a field that
was not
irrigated in
Wiggins,
Colorado
USA’s fastest growing city, Las
Vegas, had doubled its water use –
1985-2000.
Both sides of Marble Canyon are
very dry
The “Bathtub Ring” around Lake
Mead – 2004 water was at a near
record low.
For most of
Lake Mead’s
history, this had
been a shallow
part of the lake
– 2005 photo.
The drop that
caused the
“bathtub ring”
caused this too.
This is
where the
Dirty Devil
River flows
into Lake
Powell
before &
after the
2002
drought
Colorado River Downstream from
the Glen Canyon Dam
Original Delta Conditions
Prior to the construction of major
dams along its route, the Colorado
River fed one of the largest desert
estuaries in the world. Spread
across the northernmost end of the
Gulf of California, the Colorado
River delta’s vast riparian,
freshwater, brackish, and tidal
wetlands once covered 1,930,000
acres
Current Delta Conditions
Today, conditions in the delta have
changed. Like other desert river deltas,
such as the Nile Delta and the Indus
River, the Colorado River delta has
been greatly altered by human activity.
Decades of dam construction and water
diversions in the United States has
reduced the delta to a remnant system
of small wetlands and brackish
mudflats. As reservoirs filled behind
dams and captured floodwaters,
freshwater flows no longer reached the
delta.
Colorado Delta in 2004