FLOOD05425

• County: Delta
• Community: Delta
• Stream Name: Gunnison, Uncompahgre River
• Basin: Gunnison
• Title: City of Delta Confluence Park Project
• Date: 10/1/1989
• Prepared For: Delta
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

minute. BasedJn proration of the City of Delta's estimate
for a 60-acre s.lrface, this convert:s to a maximum
evaporation rat = of 2.12 cubic feet: per second.

o Irrigation 'ilater needs.
The maximu,n irrigation flow rat:e requirement: for the
landscaping in the vicinity of the fish pond was estimated
by the City of Jelta at: about 150 gpm, which converts to
0.33 cubic feet per second.

o Waterfowl al:'ea water requirements.
The waterf::lwl ponds will also experience evaporation as
well as seepage losses and evapo-transpiration from grasses
and plants. Th= evaporation rate in the wat:erfowl ponds
would be higher than 0.72 inches per day due to shallow pond
depth and highel:' water temperature.. An evaporation rate of
about 1.3 inches per day, which is 1.3 times the pan
evaporation rat,=, would be more appropriate. It will be
highly desirabl= to maintain a continuous flow through the
waterfowl ponds to avoid stagnant Ivater, biological
pollution, and::oncentration of heavy metals, especially
selenium. For 'i 20-acre waterfowl site at an evaporation
rate of 1.3 inc:J.es per day, peak evaporation would be 1.1
cfs. A more pr'=cise estimate of wat:erfowl pond flow needs
should be prepared. Waterfowl pond design is highly
specialized, an.i consultation with the Colorado Division of
wildlife in Fort Collins is suggested.

o Water quality requirements.
The conditions conducive to a healthy fish Emvironment
may require additional inflow to regulate water t:emperatures
in the summer, ,=specially in the shallower areas of the
pond. Water qUllity requirements may also dictat:e the type
of intake struc'ture for the pond, as well as: modulation of
the intake durL1g periods of poor water quality such as
excessive sedim=nt flow in the river. Water quality for the
waterfowl area3hould also be considered.

o Overflow st:::-ucture.
The overflQw structure from the fish pond to the
wildfowl pond s:,lould be configured t.o draww'ater from the
warmest depth oE the fish pond. In addition, a feature to
prevent fish miqration should be built into the overflow
structure. The overflow device should be sized t:o handle
the consumptive use of the waterfowl area, plus any minimum
outflow from th,~ waterfowl area, plus any additional flows
required for wa',:er quality maintenance in the fish pond.

The simpleJ3t overflow device ./Quld consist of a
standpipe set in the pond with the grate set at the desired
water surface elevation of the ponel. The grate should be
equipped with a fish screen. The sizing of this feature
would be modest and could be constructed with standard
materials by ci',:y crews.

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