DWR_2668843

• Title: STREAM FLOW DATA FOR COLORADO
• Year: 2009
• Document Type - Publications and Reports: Streamflow Report

Discharge.--
PLATTE RIVER BASIN
06717000 FALL RIVER NEAR IDAHO SPRINGS, CO.
Location.--
Drainage and Period of Record.--
Lat 39°45'20", long 105°33'24”, in SE1/4, Sec. 28, T.3 S., R.73W., Clear Creek County. Gage is located on right upstream
bank of the I-70 box culvert,near the Fall River Road Exit (238) approximately 20 ft. past Fall River Road.
Not determined. Gage established July 2007 at present site and datum to monitor minimum stream flow reach
and aid in the administration of water rights.
Sutron Satlink 2 Data Collection Platform (DCP) and Sutron AccuBubble unit in a 12-inch by 30-inch by 36-inch NEMA4
enclosure at a concrete box culvert with a steel sill plate. A staff gage located on the right edge of water is the primary
reference with an additional staff gage located on the left edge of water wing wall of the culver as backup (datum offset is
applicable). A single orifice line in 2-inch ridge conduit extends from the NEMA4 enclosure and terminates in a gravel
packed muffler buried in the stream bed approximately 5-feet upstream from the steel sill plate.
Equipment.--
Hydrographic Conditions.--
Gage-Height Record.--
Datum Corrections.--
Rating.--
Discharge.--
Special Computations.--
Remarks.--
Recommendations.--
Varying topography mainly consisting of highly vegetated mountainous areas. Flow is partly regulated by several reservoirs
located upstream of the gage near St. Mary’s Glacier.
The primary record is hourly averages of 15-minute telemetered bubbler data with DCP logged data as backup. Instrument
calibration was supported by 18 visits to the gage. The record is complete and reliable, except for: November 23, 2008;
October 10, 2008 and May 18, 2009; when 1-2 hours of transmitted data were either missed or never received. Hourly
values were interpolated from adjacent periods of good record without loss of accuracy. December 5, 2008 to April 6, 2009
the gage was disabled for winter and no gage-height record is available. The instrument was set once in the fall and once
in the spring. Gage height corrections of up to 0.05 ft were applied based on staff readings. The instrument was hard to
set due to unsteady flow conditions. These conditions worsened after runoff when cobble had filled in the stilling basin
behind the control. Unstable GH’s affected gage calibration, data bounce, and accuracy of measurement gage heights.
No levels were run this year.
Shifts result from material moving into the stilling basin, debris accumulation in the channel and from an incomplete
definition of the rating. With additional discharge measurements subsequent ratings should better define the channel. The
channel is composed primarily of gravel and embedded small boulders. The control at all stages is a metal sill mounted in
front of the box culvert running under I-70 approximately 5-feet below the gage. The channel is straight above and below
the gage. Rating No. 2 developed on June 28, 2008 was used all year and is defined by measurements from 3.66 cubic
feet per second (cfs) to 64.9 cfs. Thirteen (Nos. 31-43) measurements were made this year, ranging from 3.83 cfs to 61.0
cfs. The peak discharge of 137 cfs occurred at 2230 on May 31, 2009 at a gage height of 2.10 feet with a shift of -0.05
feet. The peak exceeded measurement No. 36 made on June 3, 2009 by 0.46 feet of stage and 76.0 cfs respectively.
Shifting control method was used all year. Shifts were distributed by time and all measurements were given full weight.
Measurements showed unadjusted shifts ranging from -0.06 feet to +0.06 feet.
The peak exceeded 150% (97 cfs) of the highest rating measurement. Rating 2 was extrapolated to 127 cfs (gage height
of 2.0 ft) in development. Discharge for the peak equivalent gage height of 2.05 ft was extrapolated linearly.
The record is fair, except for periods when flows exceeded 150% of the highest measurement ( June 1, 26-27), and the
instantaneous peak of May 31, 2009, which are poor due to lack of rating definition. Station maintained and record
developed by Jana Ash.
Levels need to be run. Additional reference marks and the PZF need to be established. Rating measurements are needed
with good stilling conditions. The width of the sill should be recorded and a new rating computed with comparison to the
corresponding sharp crested contracted weir. Photo of new control is needed for the station description. Cleanout of
cobble filling in front of the control should be done when the gage is opened. Consideration should be given to placing a
structure upstream for energy dissipation and interception of moving material. Also, widening and deepening the upstream
channel can be done to increase stilling.
2009Water Year