PROJ00441

• Contract/PO #: C153459
• Contractor Name: Loveland, City of
• Water District: 0
• County: Larimer
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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4.3.1 Hydrologic Data Used in Augmentation Process

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Precipitation and streamflow from other areas were examined to determine if
long-term historical records existed which could be correlated with the Big
Thompson native flows for augmentation purposes. The records used in this
analysis included monthly native flows of the Cache La Poudre River and
monthly precipitation data collected at the Vaterdale Treatment Plant (in
Loveland); Fraser, Colorado; and Grand Lake, Colorado weather stations.
Only data recorded concurrently with the Big Thompson native flows and
which were also available for periods when Big Thompson flow data were
missing were considered. The selected records were sufficient in length to
generate a 58-year historical record of Big Thompson River native flows for
the period 1927 to 1984 (calendar year).

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Precipitation records for the three weather stations mentioned previously
were selected due to their length of record and possibility of
demonstrating good correlation to Big Thompson native flows. Records from
the Waterdale station should reflect precipitation that has fallen in the
Big Thompson watershed, and thus streamflow as a result of precipitation,
although they will not necessarily correlate to spring runoff as a result
of snowmelt. Runoff resulting from winter snowfall may be better
represented by precipitation records from high mountain weather stations.
The station located near Estes Park would have been the obvious candidate
for this analysis, however, its location has been changed at times and its
use is generally not considered appropriate for long-term record analyses.
The Grand Lake and Fraser stations are located on Colorado's Western Slope
near the Continental Divide. These were the nearest high mountain stations
to the Big Thompson watershed for which records were available. Runoff
resulting from melting of winter snowfall are more adequately represented
by these stations than the Waterdale station.

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