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Discharge.--
<br />PLATTE RIVER BASIN
<br />TARRYALL CREEK BELOW TARRYALL RESERVOIR
<br />Location.--
<br />Drainage and Period of Record.--
<br />Lat. 39º13’18”,Long. 105º36’07”; in SW1/4 of sec 31, T. 9S, R. 73W, Park County, about 500 ft. downstream from Tarryall
<br />Reservoir.
<br />355 sq. mi., from DWR Dam Safety Section database. Age of the gage is not known, although the reservoir was
<br />built in 1929. DWR first ran levels in June of 1975, and installation in 1970’s is consistent with the type of
<br />materials used. The gage has been operated infrequently and records have never been kept prior to 2005.
<br />Sutron SatLink 2 satellite Data Collection Platform (DCP) with a Sutron 56-0540 shaft encoder (SE) in a 36” CMP structure
<br />located on the right downstream abutment of a bridge on Park County Road 77. Gage is operated and equipment is
<br />maintained by the Colorado Division of Water Resources (DWR) under a cooperative agreement with the Colorado Division
<br />of Wildlife (DOW), the owner of Tarryall Reservoir. There is an inside reference tape and a staff gage on the center
<br />abutment of the bridge.
<br />Equipment.--
<br />Hydrographic Conditions.--
<br />Gage-Height Record.--
<br />Datum Corrections.--
<br />Rating.--
<br />Discharge.--
<br />Special Computations.--
<br />Remarks.--
<br />Recommendations.--
<br />Natural flow of stream affected by storage in Tarryall Reservoir and diversions for irrigation and return flow from irrigated
<br />areas.
<br />Primary record is hourly averages of telemetered 15-minute shaft encoder data. The record is complete and reliable,
<br />except as follows: November 9-25, 2008 when the gage was possibly affected by ice conditions; November 25, 2008 and
<br />April 7, 2009, partial day records (shut-down and start-up days); and, November 26, 2008 through April 7, 2009, when the
<br />station was off for winter and no record is maintained. Instrument calibration was verified by twenty five visits made to the
<br />gage. No SE adjustments were necessary.
<br />Levels were run on August 27, 2008 from the reference mark on the southwest bridge abutment to the RP by DWR
<br />personnel. RP was found to be 0.014 ft low. No correction was made.
<br />Rating TARTARCO02, dated August 30, 1977 has been used since the gage was placed back into service in WY2004. It is
<br />defined by measurements from 3.65 to 206 cfs. Shifting is caused by the movement of material (sand, silt, rocks, and
<br />boulders) across the control. Frost heave can affect the first measurements of the spring, since the creek thaws before the
<br />ground does. Negative shifting is caused by the fish habitat structures constructed downstream of the gage and can also
<br />be caused by moss growth, which develops throughout the summer and continues until fall when the gage is deactivated
<br />for winter. Sixteen measurements (Nos.111 - 126) were made this year ranging in discharge from 6.29 to 289 cfs. The
<br />rating is defined to 206 cfs; flows above 309 cfs are to be considered estimated. There were no flows above 309 cfs this
<br />water year. Average daily flow was above the highest measurement of 289 cfs on June 2 and 3, 2009. Peak discharge of
<br />314 cfs occurred at 1730 June 2, 2009 at a gage height of 4.15 ft with a shift of -0.33 ft. The peak exceeded measurement
<br />No. 120, made on June 3, by 0.06 feet in stage.
<br />Shifting control method was used all year. Measurements showed shifts ranging from -0.02 to -0.33 ft. Shifts were applied
<br />as defined by measurements and distributed with some consideration to stage regarding peak discharge for the year.
<br />Shifts were applied as follows: October 1 to November 25, 2008: time proration as defined by measurement Nos. 110-112.
<br /> April 7 to the peak discharge at 2000 June 2, 2009, stage dependent shifting using variable shift table TARTARCOVST1
<br />which is defined by five measurements (Nos. 116-120) made during the period of use. June 2, 2009 to August 26, 2009:
<br />stage dependent shifting using variable shift table TARTARCOVST2 which is defined by five measurements (Nos. 120-125)
<br />made during the period of use. August 26 to September 30, 2009: time proration as defined by measurement (Nos. 126-
<br />127). All measurements were given full weight except for No. 124, which was adjusted 4% to better fit the variable shift
<br />table. .
<br />Computed record was used to estimate flows for the period of possible ice effect: November 9-25.
<br />The record is rated good, except for period of ice effect, which is poor due. This is a partial year record, no record available
<br />for November 25 to April 7. However, three discharge measurements were taken at the request of the Division of Wildlife
<br />(DOW) while the gage was out of service: No. 113, 6.29 cfs on December 29,2008 ; No. 114, 8.3 cfs on February 3, 2009;
<br /> No. 115, 14.5 cfs on March 11, 2009 . Station maintained and record developed by Mike Wild.
<br />Federal Highway Commission is planning to replace bridge and gage house in 2010; prepare new rating if project does not
<br />proceed in 2010. If project does proceed, gage datum needs to be transferred over to a temporary RM not connected to
<br />the old bridge.
<br />2009Water Year
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