8/25/2022

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Aspinall Operations Meeting

August 25, 2022

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Introductions and Purpose of Meeting

Weather Review/Outlook – Aldis Strautins (NWS)

Water Supply Review– Ashley Nielson (CBRFC)

Aspinall Unit Operations – Erik Knight (USBR) 

Special Flow Requests and Discussion 

Reports of Agencies and Organizations – All

Conclusions

(Next meeting date – Jan 19th or Jan 26th ?)

August 2022

Weather Outlook

Aldis Strautins

National Weather Service

Grand Junction, CO

http://www.weather.gov/gjt

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August 2022 Outline

• Precipitation and Temperature

• SNOTEL: Snow Water Equivalent and Precipitation

• Drought

• ENSO

• Weather outlook

Water August 2022  Year 2022 through mid August

Temperature

Departure from normal

Precipitation

% of normal

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Water August 2022  Year 2022 through mid August

Temperature

Departure from normal

Precipitation

% of normal

August 2022 Sep – Nov, 2021 ‐ Precipitation

(percent of normal)

Dry fall for three quarters of the western slope going into the winter season

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Water August 2022  year Precipitation (different stories)

Oct 1 – Dec 31, 2021

Dry Nov and early Dec / Very wet late Dec

Jan 1 – Mar 31, 2022

Below normal since Jan 1

Water August 2022  year Precipitation (different stories)

Jun 25 – Aug 23, 2022 Mar 1 – May 31, 2022

Below normal

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August 2022 June and July 2022

Precipitation

% of normal

Precipitation

% of normal

August 2022 August 2022

Temperature

Departure from normal

Precipitation

% of normal

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August 2022 SNOTEL Snow Water Equivalent – NRCS

Yay...Late December Snow

Yay...Late February Snow

Ok...Some March and

early April Snow

Melt much faster than

normal

Gunnison Basin

August 2022 SNOTEL Snow Water Equivalent – NRCS

As of April 1, 2022

99% of Median as a whole

but there is a different

Story depending were in

the basin you look

Gunnison Basin

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August 2022 SNOTEL Precipitation – NRCS

Precipitation

Yay...Late December Snow

Yay...Late February Snow

Ok...Some March Snow

Summer Rains started late

June

102% of normal

Gunnison Basin

August 2022 SNOTEL Precipitation – NRCS

Water Year 2022 thru August 24, 2022 October 1, 2021 – April 1, 2022

Gunnison Basin

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August 2022 Drought

Drought Monitor (Colorado Basin View)

August 2022 Drought

Drought Monitor (Regional View)

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August 2022 ENSO ‐ Outlook

Season La Niña Neutral El Niño

JAS 86 14 0

ASO 80 20 0

SON 80 20 0

OND 79 20 1

NDJ 72 27 1

DJF 60 36 4

JFM 47 47 6

FMA 32 59 9

MAM 18 68 14

CPC/IRI Early‐Month Consensus ENSO

Forecast Probabilities

(using NWS CPC classification system)

La Nina this Spring ‐ Maybe Neutral next Spring

August 2022 ENSO

North of Colorado – Dry and Warm

South of Colorado – Wet and Cool

North of Colorado – Wet and Cool

South of Colorado – Dry and Warm

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WPC August 2022  7‐Day Precipitation Outlook

Accumulation period from Aug 25 ‐ Sep 1

August 2022 Outlook

Aug 30 – Sep 3 Aug 30 – Sep 3

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August 2022 Outlook

Sep 1 – 7 Sep 1 – 7

Monthly August 2022  Outlook

Precipitation

September

Temperature

September

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August 2022 Seasonal Outlook

Precipitation

Sep/Oct/Nov

Temperature

Sep/Oct/Nov

August 2022 Seasonal Outlook

Precipitation

Oct/Nov/Dec

Temperature

Oct/Nov/Dec

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August 2022 Seasonal Outlook

Precipitation

Nov/Dec/Jan

Temperature

Nov/Dec/Jan

August 2022 Seasonal Outlooks

Precipitation                                                                                             Temperature

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August 2022

My Last Aspinall Meeting

Aldis Strautins

National Weather Service

Grand Junction, CO

http://www.weather.gov/gjt

Aspinall Operations Meeting

August 2022

Water Year 2022 

Runoff Review

Ashley Nielson

Hydrologist

Colorado Basin River Forecast Center

National Weather Service/NOAA

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● Water Year 2022 Conditions Summary

○ Precipitation

○ Snow

● 2022 April-July Observed Volumes

● 2022 Water Supply Forecast Performance

● Current conditions 

○ Soil Moisture

○ Streamflow

● Summary

Outline

April May

June July

Precipitation: April-July

Gunnison Basin 

Precipitation

as a % of Average 

OctMar95

April 50

May 45

June 200

July 155

OctJul100

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Water Year 2022 Gunnison SNOTEL SWE Summary

Peak SWE: Below normal

Melt: Early

Peak SWE: Above normal

Melt: Early

Peak SWE: Above normal

Melt: Late

Peak SWE: Below normal

Melt: Early

April 1

Snow Conditions: CBRFC Model Snow Water Equivalent

May 1 May 15

Schofield Pass

East River- Almont

● Peak SWE

■ Near to Above normal: Northern half of basin

■ Below normal: Southern half of basin

● Peak SWE Timing

○ Mixed depending on basin location and elevation

● Melt Out

○ Mixed depending on basin location and elevation

■ Early melt

● Higher elevations 

● Southern basins

% of Median

Median

June 1

>11000’ 

9500’-11000’

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Taylor Park

72 kaf / 77%

East-Almont

152 kaf / 86% 

Tomichi Ck

35 kaf / 52% 

Lake Fork

71 kaf / 60% 

Paonia

54 kaf / 66%

Surface Ck

12.6 kaf / 86%

Gunnison

Grand Junction

855 kaf / 64%

Ridgway

57 kaf / 62% 

Crystal

484 kaf / 63% Blue Mesa

431 kaf / 68% 

kaf / % of avg / 1991-2020 

Below average volumes

Range: 50% - 86% of average

Note: volumes are unregulated

Note: values are preliminary

Gunnison River Basin 2022 April-July Observed Volumes

Apr-Jul Observed

Forecasts decreased from April through June due to much below normal precipitation. The 

observed volumes were either below or near the 90% forecasts for January-April.

Average

530 kaf

83% 490 kaf

77% 430 kaf

68%

Blue shading: Daily Raw Model Guidance 90% - 10% exceedance 

range

Blue line: Daily Raw Model Guidance 50% exceedance

Pink line: Official forecast 90%, 70%, 50%, 30%, 10% exceedance

Brown dotted: Average observed

Orange dashed: 2022 Observed Streamflow

Water Supply Forecast Evolution: Blue Mesa Reservoir Inflow

Dry April / May

Median

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Forecast Performance

January April

WY2022 Forecast Error Compared to Normal Model Error

Ideally, the current year forecast should have a 

similar or lower error than the model. If the current 

year forecast error is higher than the model, it 

suggests a problem with the following: 

● Model initial conditions

● Model adjustments during the season

● Data quality issues

May

Warm Colors: WY22 forecast error > typical model error

Black: WY22 forecast error = typical model error

Cool Colors: WY22 forecast error < typical model error 

What happened?

2022 Model Errors:

● Model SWE too high

○ Model uses precipitation to build snowpack

○ Independence Pass more representative of conditions?

■ More weight was put on Upper Taylor and Park 

Cone SNOTELS as Independence Pass seemed 

like an outlier. This may have been the wrong idea.

○ Removed snow from the model in June

● The model did not melt enough snow in May; held onto the 

snow in the model as streamflow wasn’t showing response

○ Model soil moisture too wet?

○ Sublimation?

○ Dust impacts?

● Continue to investigate a suite of other snow products to help 

verify and reality check model SWE

● Taylor River errors impacted downstream forecasts including 

Blue Mesa Reservoir.

● Unusual year and a particularly tricky Spring with a warm/dry 

period followed by a wet/cool period during the typical runoff 

time. The model often struggles with this kind of transition.

Fall 2021

April 1 Model SWE and SNOTELS

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Late August Conditions

*Model snapshot. Provisional data that will change*

Modeled Soil Moisture: Aug 16 2022

• Water Supply Conditions:

• Below normal soil moisture conditions entering the 2022 spring runoff season

• April-July observed unregulated runoff volumes ranged from 50-85% of average.

• Peak SWE and melt timing were dependent on basin location and elevation 

■ Near to above normal: Northern half of the basin

■ Below normal: Southern half of the basin

• Below normal precipitation in April-May

• Above normal precipitation in June-July

• Warm and dry spring weather had a significant impact on water supply conditions

• Current conditions

■ Improved baseflow and soil moisture conditions

● Aug-Oct weather will determine final conditions prior to winter

• Water Supply Forecasts

• Forecasts decreased from April-June due to below normal precipitation

• Observed volumes were near or below the 90% forecasts

• Forecast error was higher than the normal model error; specifically above Taylor Park Reservoir

■ Model snow states too high

■ Model melt rates too slow

• Weather 

• June-August weather has brought precipitation and hydrologic relief to the region

Summary: 

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Contact Info

Contact Information

• Ashley Nielson - Gunnison River Forecaster

• ashley.nielson@noaa.gov

• 801-524-5130 x333 

• Operational Hydrologist: in office

• 801-524-4004

• cbrfc.operations@noaa.gov

CBRFC Webpage

https://www.cbrfc.noaa.gov/

CBRFC Water Supply Presentations

https://www.cbrfc.noaa.gov/present/present.php

Contact Info:

RESERVOIR AND RIVER STATUS

Blue Mesa Reservoir content is currently at 346,000 acre‐feet at an elevation

of 7456 feet. (42% full)

Crystal Dam is releasing 1450 cfs and flows in the Gunnison River through the

Black Canyon are 440 cfs

Flows in the lower Gunnison River at the Whitewater gage are ~1000 cfs,

above the baseflow target of 900 cfs

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SPRING RUNOFF 

Actual runoff for major rivers in the Gunnison Basin fell in the 55‐85% of

average range

The May 1 runoff forecast for Blue Mesa Reservoir put 2022 into the

Moderately Dry hydrologic category. Actual runoff was 68% of average.

The ROD targets in the Moderately Dry category call for a 1 day peak flow of

~7,000 cfs at Whitewater. However,  the drought rules allow the peak flow at

Whitewater to be reduced to 5,000 cfs when Blue Mesa content is less than

400,000 acre‐feet.

There were no half bankfull or peak flow duration targets.

Drought rules that lower the baseflow targets are in effect in a Moderately

Dry year

The Black Canyon water right peak flow target was 2,412 cfs

103% of normal

seasonal peak

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Year Type Blue Mesa 

Forecasted 

Desired Peak at 

Whitewater

Duration of Half Bank 

(8,070 cfs)

Duration of Peak Flow 

(up to 14,350 cfs)

April-July Inflow

Af cfs Days Days

DRY < 381,000 900 0 0

MOD DRY 381,000 to 516,000 2,600 to 8,070 0 0

AVG DRY 516,001 to 709,000 8,070 10 0

AVG WET 709,001 to 831,000 8,070 to 14,350 20 2

MOD WET 831,001 to 1,123,000 14,350 40 10

WET >1,123,000 14,350 60 15

Spring Peak & Duration Targets

Based on Hydrologic Year Type

Actual

430,000

WW Peak Flow = 5800 cfs – occurred on May 19

BC Peak Flow = 2700 cfs – occurred on May 18

1 day at Peak Flow

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SUMMER/FALL OPERATIONS

Releases from the Aspinall Unit to meet the baseflow target on the lower

Gunnison River at Whitewater have resulted in flows of 350 cfs to 550 cfs in

the Gunnison River through the Black Canyon and Gunnison Gorge this

summer

Gunnison River flows through the Canyon/Gorge are expected to be between

350 cfs and 450 cfs for the remaining summer and fall months

On December 31, 2022, Blue Mesa Reservoir is expected to be at elevation

7446 feet with a content of 287,000 acre‐feet (35%  full)

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Baseflow Targets

Drought Rule

 During Dry and Moderately Dry years, if Blue Mesa Reservoir content

drops below 600,000 af, the Whitewater baseflow target is reduced from

1050 cfs to 900 cfs until Blue Mesa Reservoir content exceeds 600,000 af

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Questions?

Special Flow Requests and Discussion – All

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Reports of Agencies and Organizations – All

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