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

inset within a series of alluvial terraces overgrown by dense stands of tamarisk (T amarix

sp.), Russian olive (Elaeagnus anustifolia), and a few cottonwoods (Populus sp.).

Although the banks and flood plains are predominantly made up of fine-grained

alluvium, the bed of the river is predominantly gravel. .

Approximately 21 rm downstream from the study reach, the exposed bedrock at

river level changes from the Green River formation to the Uinta formation. From Taylor

Draw Dam to the mouth, river, has its steepest slope of 0.0044 for the 2 rm across the

transition. Downstream from this point the river flows for 12 rm through entrench~d

meanders eroded into the Unita formation. The distance between canyon walls increases,

and in the last 19 rm of its course, the river flows across a 1.2 mile wide alluvial valley.

The slope nearing the confluence is 0.0005.

METHODS

Flood Frequency Analysis

Seventy-seven years of annual peak floods measured at the Watson gage were

used to calculate the mean annual flood, and the return period of other annual peak

discharges. Peak flood values are available at the Watson gage for 1904 and 1905, 1923

to 1979, and 1985 to 1997. Data from the Stateline gage (station 09306395) were used

for the period when the Watson gage was inactive, between 1979 and 1985. The plotting

position for each annual flood was determined using the formula:

Rl = (n + l)/M
where Rl is the recurrence interval of the flood, n is the number of years of record, and M
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