7086

• UCREFRP Catalog Number: 7086
• Author: U.S. Fish and Wildlife Service.
• Title: Indexed, Annotated Bibliography of the Endangered and Threatened Fishes of the Upper Colorado River System.
• USFW Year: 1977.
• USFW - Doc Type: Denver, Co.
• Copyright Material: YES

from which 20,000 to 26,000 pounds of trout
averaging 1.0 to 1.5 pounds have been harvested
each year since 1970. The river is large:
over 300 feet wide, average depth of 2.0 feet.
Flows range from 300 cfs to 15,000 cfs over a
gradient of 4.8 feet per mile.
Prior to construction of Fontenelle
Reservoir the river supported fish of little
sport fishery value--carp, suckers, and catfish.
Alteration of water temperature, water clarity,
and flows through impoundment created a river
environment capable of supporting salmonid
fisheries. The fisheries has developed with an
average daily flow of 1600 cfs. The fishery
resource of the Fontenelle tailwater is competi-
tion with industry, agriculture, and municipal
interests for the river water. During the
summer and fall of 1973 a series of in-stream
measurements were taken at four representative
stations of flows of 16 cfs, 800 cfs (50% ADF),
500 cfs (30% ADF), and 300 cfs (18% ADF). The
study was conducted to evaluate the impact of
reduced flows on fish and wildlife and to
formulate an optimum flow regime.
Parameters measured at the established
stations were depth, velocity, cross sectional
areas, and wetted perimeter. Additionally,
aerial photographs were taken over the entire
73 miles of stream at the four discharges. In
order of magnitude those parameters affected by
flow reduction were volume, velocity, cross-
sectional area, depth, width, and total wetted
surface area.
Total surface area at each flow release
was broken down into 64 categories comprised of
depth (feet) and velocity (feet per second)
intervals from 0.5 to 3.5. Specific depth-
velocity ranges were assigned to potential food
production habitat, shelter microhabitat and
habitat in which particular size trout can be
sustained. Total surface area of water available
at each flow to provide these specific habitat
requirements was determined. Of the four flows
studied in 1973, the flow of 800 cfs appeared
to provide the most balanced habitat diversity
in meeting most production and survival needs
for all sizes of trout.
To perpetuate the existing fisheries
resource a winter (November through March)
survival flow of 500 cfs was recommended and,
if necessary, an emergency short-term (30 days)
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