Evaluation of Instream Flow Methods and Determination

• Year: 1979
• Title: Evaluation of Instream Flow Methods and Determination of Water Quantity Needs for Streams in the State of Colorado
• CWCB Section: Stream & Lake Protection
• Author: R. Barry Nehring
• Description: Evaluation of Instream Flow Methods and Determination of Water Quantity Needs for Streams in the State of Colorado
• Publications - Doc Type: Tech Report

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RESULTS AND DISCUSSION

Single Transect (R-2 Cross) Method

All of the minimum flow recommendations in Table 4, except
for the South Fork of the Fryingpan River, were based on data
collected during the Phase II investigation. The Phase II recom-
mendation of 30 cfs on the South Fork of the Fryingpan was based
on a very atypical critical riffle and turned out to be excess-
ively high when compared to the results of the other methodologies.
This critical riffle was almost twice as wide as the rest of the
stream channel due to the division of the stream into two channels
a few feet below the transect. A minimum flow recommendation of
6 cfs has been in effect for a year or more on this stream, based
on a previous critical riffle transect taken in the same general
vicinity (within a few hundred yards).

Table 4. Minimum flow recommendations using the Single Transect
(R-2 Cross) Method.

Stream name

Minimum flow
recommendation (cfs)

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l. Cache la Poudre River, Little South Fork
2. Carnero Creek, South Fork
3. Cucharas River
4. Cunningham Creek
5. East River
6. Fryingpan River I (Taylor Creek)
7. Fryingpan River II (Castle View)
8. Fryingpan River (North Fork)
9. Fryingpan River (South Fork)
10. Gunnison River, Lake Fork
11. Huerfano River
12. Rio Grande River, South Fork
13. St. Louis Creek
14. Sangre de Cristo Creek
15. South Platte River I - above Denver W.B.
diversion
l6. South Platte River II - below Marston Canal
17. Williams Fork River I - below Kinney Creek
18. Williams Fork River II - at Ute Creek

20
2
5
4
65
55
65
8
6 (30)
45
4
40
9
2

60
l8.5
37
40

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