9605

• UCREFRP Catalog Number: 9605
• Author: Schmidt, J. C. and e. al.
• Title: Flow Recommendations for the White River, Utah-Colorado Draft Report.
• USFW Year: 2002.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

The distribution of mean monthly discharges has not changed substantially since

the completion of Taylor Draw Dam. Hydrographs representing three time periods show

that the montWy mean daily discharge has not changed appreciably since the completion

of the dam (Figure A-9). Baseflow discharges after the dam (1984 - 1997) are slightly

higher than the two decades directly preceding the dam (1965 -1983), but do not differ .

from the period between 1923 and 1964.

Identification of the Modern Flood Plain and Banlifull Discharge

Bankfull discharge is defined as the discharge at which the active flood plain

begins to be inundated. In the detailed study site, the lowest elevation depositional

surface that is longitudinally correlative begins to be inundated at a discharge of

approximately 3,700 cfs, which has a recurrence of 1.7 years on the long-term annual

series (Figure A-I 0) and about three years for the partial duration series for the period

between in 1984 and 1997. This surface is characterized as a flat low-elevation surface

comprised of predominantly fine-grained alluvium that overlies cobbles and gravels. The

surface has been colonized by young vegetation such as horsetail grasses, and young

tamarisk. This surface lacks mature woody vegetation such as large tamarisk or Russian

olive (Figure A-II).

At least two other distinct flood plain-like surfaces exist adjacent to the White

River within the detailed study site (Figure A-12). Figure A-13 shows the longitudinal

profile of these surfaces, surveys of actual river conditions of known discharges, and

thalweg elevations. The highest elevation surface identified in this study is a terrace

approximately 1 m above the active flood plain. It is inundated at discharges of
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