FLOOD01012

• County: Lake
• Community: Lake County
• Stream Name: Lake Creek, Arkansas River
• Title: Hydrology Report for Lake County
• Date: 7/1/1981
• Prepared For: Lake County
• Prepared By: MSM Consultants, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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PROBABILITY STUDIES, ANNUAL PEAK DISCHARGE AT
MALTA AND HALFMOON DIVERSION DAMS

Purpose

Data from the subject study is needed for cost estimates and other
consideration by the Project Office.

General

The proposed site of the Malta diversion dam is on the Arkansas
River near the point where the 9705 foot contour crosses the channel.
This is approximately 0.4 mile below the confluence of East Fork and
Tennessee Fork, and approximately 0.5 mile upstream from the~crossing
of County Road No. 104. '(See accompanying sketch map)

The proposed site of the Halfmoon diversion dam is approximately 0.3
mile downstream from the gaging station on Halfmoon Creek. (See
accompanying sketch map)

Computations

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A short record of streamflow is available from gages located near
the ,confluence of the East Fork Arkansas River and Tennessee Fork.
Combining the record from these gages, a composite record for a point
on the Arkansas River just below .the confluence of the two forks was
constructed. This record of annual peaks below the confluence was
computed as follows. To the annual peak on the East Fork the mean
daily flow for the corresponding day on the Tennessee Fork was added.
The same procedure was followed using the peak value from the
Tennessee Fork record and the mean daily from the East Fork. For
each year the two resulting values were compared and the larger of
the two was selected as the annual peak for the point below the
confluence. Standard probability computations were made using the
computed peaks. The computations and plotted results accompany this
narrative.

The intervening drainage area between the proposed Halfmoon diversion
damsite and the gage on Halfmoon Creek is considered negligible.
Therefore, the annual peak of the 19 years of record at that gage
was used in standard probability computations to compute the frequency
of the various magnitude discharges at the Halfmoon diversion dam.
The 'computations and plotted results are attached.

Comparison with the Gaged Record at Granite

Streamflow records are available on the Arkansas River a~ Granite,
Colorado, at random periods during the years 1895, 1899 and 1901,
and are continual from April 1910 to present. The early period

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