9385

• UCREFRP Catalog Number: 9385
• Author: Hawkins, J.
• Title: Responses by Flaming Gorge Technical Integration Team to April 4, 2000, Minority Report from John Hawkins
• USFW Year: 2000.
• USFW - Doc Type: Flow and Temperature Recommendations for Endangered Fishes in the Green River Downstream of Flaming Gorge Dam ‎(hereafter the Flow Report.
• Copyright Material: NO

recommended flow in average years is almost double the flow that occurred in pre-dam
conditions is misleading because it ignores the variability in the pre-dam data. The value
presented in the minority report is the mean flow in average years, and there is considerable
variability around that mean value. Even within a year, variability on the order of the difference
between our recommended flows and pre-dam flows occurred regularly.

Comment:
The limitations of these studies, the significant scientific uncertainty about the base flow
magnitudes needed for fish recovery, and the arbitrary nature of the recommended scaling of
base flow magnitudes should be more clearly recognized in the Flow Report. When faced with
such limitations in the data and such uncertainty, we think that a more natural scaling should be
applied. We suggest that a more natural scaling be based on the pre-dam base flow magnitudes
for different hydrologic conditions, as presented in Table 3.8 of the Flow Report (Page 3-25).
These data of more natural base flow magnitudes indicate that there may be important
differences in the magnitude and scaling between the summer and winter base flow periods.
Thus, one step towards a more natural scaling would be to provide separate flow
recommendations for the two base flow periods (summer and winter) and to scale each more in
accordance with natural conditions. For comparison to the Flow Report's recommended ranges
of base flow magnitude, we offer the follOWing simple alternative scaling for the combined
summer through winter period (Excel Figure 3).

Response: We concur that there is uncertainty regarding our base flow recommendations, and
that we should add some wording to that effect in the final report. However, we do not feel that
this uncertainty changes our recommendations in any way, and that these recommendations are
supported by the information available. Regarding the suggestion that separate summer and
winter base flow recommendations be made, it should be noted that there are no data to indicate
that winter base flows that are lower than summer base flows would benefit endangered fishes.

Comment:
This scaling is centered around a mean magnitude of 1800 eft for an average hydrologic
condition, which is near the lower range of the current base flow recommendation and is within
the range supported by the studies listed above. The difference between this mean base flow
magnitude and the pre-dam magnitude for an average hydrologic condition is scaled according
to the mean pre-dam base flow magnitudes for each hydrologic condition using data from Table
3.8. The results in Excel Figure 3 are offered as the top end of the range for base flow
magnitudes for each hydrologic condition.

Response: There are a number of problems with this comment and the associated Figure 3.
First, 1800 cfs (51 m3/s) is not, as stated in the comment, near the lower range of the current base
flow recommendation, but rather in the middle (43 to 67 m3 Is) of the range. Figure 3 appears to
be an attempt to lend an air of credibility to the completely arbitrary recommendations promoted
in the minority report. The graph presents categorical data (hydrologic condition) as evenly
spaced continuous data and then performs a regression on the resulting "relationship" between
hydrology and mean base flow. In fact, hydrologic conditions as defined in the report are ranges

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