7824

• UCREFRP Catalog Number: 7824
• Author: Miller, W. H., et al.
• Title: Colorado River Fishery Project, Part III, Final Report, Contracted Studies.
• USFW Year: 1982.
• USFW - Doc Type: \
• Copyright Material: NO

• The Mineral Bottom results reflected the extremely restricted range
of suitable flows for YOY at that study site (Figure 16). While flow
reductions have not been so severe as those upstream at Ouray (because of
intervening tributaries and ground water effects), they appear to have
provided some positive physical habitat effect. Oddly, at the 50%
percentile exceedence level (noting those habitat values expected to
occur during one-half of the months of record) the depletions have caused
very little change in habitat except during August. Depletions during
August appear to have brought the flows within the range of suitability,
whereas depletions during the runoff months were still not great enough
to result in suitable low flow levels.
Results at the Potash site somewhat reflected those at Mineral
Bottom (Figure 17). Again, while reductions in flow were somewhat
uniform, they had not been as great as those in the Upper Green River.
Also, the reductions were proportionally greatest during runoff months;
during September, the percentage reduction was quite low.
Only during July was YOY physical habitat effected significantly by
flow reductions; again, a positive effect was noted. In general the
effects of flow depletions upon the nursery habitats of both rivers
appear to be either neutral or positive, with respect to depth, velocity,
and substrate.
The actual flow times series (1960-1980) were completed for use in
further refinements of flow recommendations and determinations of effects
of recent flow events upon endangered fish populations. This report does
not provide an in-depth analysis of the actual flow time series; more
will be done with this information when more detailed life history infor-
mation is made available.
Temperature Model Results
Table 2 identifies the respective gages and their associated
adjusted multiple correlation coefficients (r) and probable difference
(d). The correlation coefficient was the ratio of explained variation of
the predicted temperature to the total variation of the published tem-
perature. The probable error was the expected difference range of the
published temperature with respect to the predicted temperatures; i.e.,
50 percent of the published temperatures fall within the probable dif-
ference limits of the predicted temperature.
The regression models for the headwater and point source gages were
used to predict the initial (headwater) water temperatures necessary
for the physical process instream water temperature model. The regres-
sion models for the validation gages were used to predict temperatures
against which to measure the performance of the physical process model.
• Temperature Simulations at Black Rocks and Ouray
At Black Rocks, the May flows ranging from 7,000 to 13,500 cfs were
associated with temperatures ranging from 15° C to 13° C (Figure 18).
The mean annual May flow (10,000 cfs) was sufficiently high to maintain
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