Flaming Gorge Technical Working Group

June 14, 2012, 10:00 a.m.

Conference Call Record

Attending: 

Fish and Wildlife Service: Kevin McAbee, 

UCRIP – Tom Chart, Jana Mohrman, Kevin Bestgen

Reclamation – Katrina Grantz, Malcolm Wilson, Beverley Heffernan, Ed Vidmar, Lee 

Traynhm, Peter Crookston

Western – Jerry Wilhite, Clayton Palmer

Argonne National Lab – Kirk LaGory

Agenda:

• Review hydrology and possible reservoir operations scenarios [Reclamation]

• Western Proposal

• FWS Proposal

• Discussion [FGTWG members] 

• FGTWG decision on recommendation to Reclamation 

Overview:

The primary purpose of the call was to discuss flows during the Early Base Flow Period 

(June-Sept 30th). Katrina Grantz of Reclamation, acting FGTWG chair, filling in for 

Heather Hermansen, lead the meeting. 

Hydrology Discussion:

Katrina Grantz reviewed spring and summer/fall basin hydrology and Flaming Gorge 

reservoir operations information. The spring peak release for the Larval Trigger Study 

was 7,400cfs for two days plus shoulder days at 6,400 and 6,000cfs. Flows at Jensen, UT 

exceeded 8,300 cfs for five days, which met the targets for the established Dry hydrologic 

classification. (For spring operations, the FGTWG had agreed to targets in the Dry 

hydrologic classification due to the extremely dry conditions on the Yampa this year.) 

The June forecast for unregulated inflow to Flaming Gorge during the April – July season 

is 590kaf (~84% exceedence) and is trending down. This forecast corresponds to the 

lower end of Moderately Dry hydrologic classification. Flows on the Yampa are 

extremely low, (1st or 2nd percentile) at ~700cfs. For the current Moderately Dry 

hydrologic classification, the 2000 Flow and Temperature Recommendations recommend 

flows at Jensen in the range 1,100cfs-1,500cfs. Based on hydrology, Katrina

recommended a target baseflow near the lower end of the moderately dry hydrologic 

classification (in the range of 1,100 to 1,300cfs at Jensen). 

Katrina presented 3 operations scenarios: targeting (1) 1,100cfs at Jensen, (2) 1,300cfs at 

Jensen, and (3) 1,500cfs at Jensen, using the current forecast for the Yampa. 

Western Proposal:
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Jerry Wilhite of Western presented a proposal for the Early Base Flow Period. Jerry 

noted that there is significant uncertainty in both the hydrology and in the results of the 

Larval Trigger Study and suggested that the FGTWG revisit the base flow again in early 

July after more information is available. Jerry suggested a target of 1,100cfs at Jensen 

until the first week of July after more information is available (from Argonne) regarding

how much habitat we currently have. 

Fish and Wildlife Proposal:

Kevin McAbee of the Fish and Wildlife Service proposed maintaining summer baseflows 

close to 1,500 cfs at Jensen, and, if necessary, allowing flows in the wintertime to drop 

lower than 1,500 cfs. This request was based on habitat data and flow to catch per unit 

effort data. FWS expressed the general observation that when flows are below 1,500cfs 

in the summer, considerably fewer young of year are observed in the system. FWS also 

indicated that based on 2011 backwater data, flows of 1500 cfs provide more habitat, 

especially in depth, for age-0 pikeminnow. During discussion Reclamation noted that 

the 2011 backwater data shows minimal difference in surface area habitat for flows 

between 1300 and 1500 cfs. 

Discussion:

The group considered the current hydrology, hydrologic classification (Moderately Dry), 

reservoir operations (elevation projections under various release scenarios) and 

information about the relationship between flows at Jensen and backwater area / volume 

(from 2011) and fish catch per unit effort data.

Recommendation:

The FGTWG recommended that the FGTWG reconvene on July 6th after Argonne 

National Labs has remapped the backwaters to provide an updated relationship between 

flow and backwater area/volume. At this time there will also be updated hydrologic 

information. Kevin McAbee thought this was a reasonable plan, but indicated that he will 

continue to consider the long term Age-0 pikeminnow fall monitoring data set, which 

indicates there is a lower base flow threshold that appears biologically important. There 

were no dissenting opinions within the FGTWG on this interim recommendation.

In the interim, the group recommends that flows at Jensen be maintained at or above 

1,500cfs. Given the current and forecasted flows of the Yampa, the group recommends a 

release from Flaming Gorge of 1,300cfs to achieve this flow until after an updated formal 

recommendation from the FGTWG is made at or after the July 6th meeting. There were 

no dissenting opinions within the FGTWG on this interim recommendation.

Action Items:

AI - Reclamation (Katrina) reduce releases from Flaming Gorge to 1,300cfs and monitor 

that flows at Jensen are at or above 1,500cfs until July 6th

AI – Reclamation (Katrina) schedule FGTWG conference call for July 6th 10am. 

AI- Argonne (Kirk LaGory and crew) will remap the backwater habitat and report on the 

next call
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Next Call: July 6th 10am-11am

FGTWG will review information from Argonne, updated hydrology, and any other 

additional information to decide on the group’s recommendation for flows during the 

Early Base Flow Period.