8106

• UCREFRP Catalog Number: 8106
• Author: Anderson, R. M.
• Title: Riverine Fish-Flow Investigations.
• USFW Year: 1998.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

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Maybell is 8,463 cfs. The median, 50% exceedence, or 2-year peak flow recorded on the

Maybell gage is 10,000 cfs and the ten-year flood is 14,634 cfs. The peak flow in 1996

was 14,700 cfs, and in 1997 it 16,400 (20 year flood).

The minimum flow for the 82 years of record at Maybell was 3 cfs in 1934. The

second lowest minimum flow was 7.9 cfs in 1994. Annual minimum flows have been 45

cfs or less 13 times during the last 82 years. Minimum flow exceeded 54 cfs in 80% and

74 cfs in 70% of the years since 1916. Half the years have a minimum flow exceeding

128 cfs, and minimum flow exceeded 235 cfs in 20% of the flow record (Figure 3).

Ninety percent, 80 %, 70 %, 60 % and 50 % exceedence flows are given for the base flow
period in Figure 4.

Currently, approximately 110,000 acre feet (AF) of water is depleted for out-of-

river use per year, about 10% of the total annual yield. According to a flow model

recently developed by CWCB, during the 17 year period 1975 to 1991, about 57% of

total annual depletions occur in the months of April, May and June. Natural or virgin

flow was reduced by an average of only 6% for those three months. The fall and winter

months of October, November, December, January, February and March accounted for

eight percent of the annual water diversions and natural flow was reduced by about six

percent. Depletions have the greatest impact during August and September, when natural

flows were reduced by 28% and 33%, respectively for the 17 year modeling period. The

model determined that in six of the 17 years, natural flow was depleted by 50% or more

and predicts that additional water development will likely double the number of years

when total depletions exceed half the natural flow.

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