5001

• UCREFRP Catalog Number: 5001
• Author: Nicola, S. J.
• Title: Fisheries Problems Associated With the Development of the Lower Colorado River.
• USFW Year: 1981.
• USFW - Doc Type: \
• Copyright Material: YES

• •
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characteristic that allowed these four species to successfully cope with the
swift river environment is their large body size. This is carried to the
extreme by the Colorado squawfish, the'largest of the family Cyprinidae,
reported to have reached lengths of 185 cm and weights of 45 kg.
The lower Colorado River probably served as a nursery and feeding area
for the squawfish, sucker, and chubs. These species spawned in the mid-
elevation reaches of the main Colorado and its tributaries, over clean
gravel bottoms where the demersal eggs adhered to stones. Spawning took
place in the spring when water temperatures reached 21°C. The spring
spawning migrations were rather spectacular and well known to early
settlers along the. tributary rivers. The migratory habits of the squaw-
fish earned them the local name of Colorado white salmon from early settlers
who also found them to provide great sport on hook and line. But they and
and the humpback suckers oftentimes fulfilled a more utilitarian purpose.
They were frequently gathered from their spawning streams, or from
irrigation ditches into which they strayed, by pitchfork-wielding farmers
who hauled them away by the wagonload to feed to their hogs or to dump
in their fields to fertilize their crops.-
The life histories of the bonytail and humpback chubs in the lower river are
less well known than those of the squawfish and sucker. Because of the
remoteness and inaccessibility of the river, and the difficulty associated
with working in such a large and extensive system, little-scientific data
were collected on the life history or biology of the native species before
their habitat was disrupted and they began to decline.
DEVELOPMENT
The first successful appropriation of water in the-lower Colorado occurred
in 1875, when a settler named Blythe dug an irrigation channel from the river
to his farm in the Palo Verde Valley. Such was the pattern of water. use for
the next 60 years. In 1900, a land development company was formed in
California's Imperial Valley which led to the first large-scale agricultural
diversion of water in 1901. A canal was, dug from the river near Yuma which
soon became blocked at the. intakes by silt. The intake was dredged in 1904
and the problem appeared solved. However, runoff during the winter of
1904-05 was the heaviest in many years and a large volume of water was soon
overflowing down the canal into the Salton Sink. Before the flow could be
controlled there followed another winter of exceptionally high runoff and
the Colorado suddenly left its natural channel to flow completely down the
new channel formed by the diversioh canal. The Salton Sink continued to
receive all of the Colorado's immense volume of water, forming an inland
sea (the Salton Sea) of over 1,000 km2. In October 1906, the river was
finally diverted back to its natural course following nearly 5 months of
continuous filling and diking by the Southern Pacific Railroad Company.
This episode is an example of a lesson that is constantly being relearned:
that changing the nature of the dynamic and powerful Colorado is not as
simple or as predictable as it may seem.