Navajo Unit Operations

Coordination Meeting

August 24, 2021 1:00 PM

Microsoft Teams Virtual Meeting
• Introductions

• Drought Response Operations – Katrina Grantz, Reclamation

• Weather Summary and Outlook– Aldis Strautins, NWS

• Streamflow Summary and Outlook – Ashley Nielson, CBRFC

• Review of operations to date WY 2021

• WY 2022 planned operations

• Comments and Reports

Agenda
Weather Outlook

August 2021

Aldis Strautins

National Weather Service

Grand Junction, CO

http://www.weather.gov/gjt
The Past

August 2021

Precipitation - % of normal

Water Year 2020

Water year 2020 Aug – Oct 2020
The Past

August 2021

Water Year 2021 through April

Temperature

Departure from normal

Precipitation

% of normal
The Past

August 2021

Water Year 2021

Temperature

Departure from normal

Precipitation

% of normal
Past Outlook

April 2021

Temperature Precipitation

Jul/Aug/Sep – April Outlook
The Past

August 2021

July 2021

Temperature

Departure from normal

Precipitation

% of normal
The Past

August 2021

August 2021 so far

Temperature

Departure from normal

Precipitation

% of normal
Snow

August 2021

SNOTEL Snow Water Equivalent – NRCS

Southwestern Colorado

85% of 

Normal 

Peak
Drought

August 2021

April 13, 2021 August 17, 2021

Drought – Monitor
Drought

August 2021

August 17, 2021 August 11, 2020

Drought – Monitor
Season La Niña Neutral El Niño

JAS 41 59 0

ASO 53 46 1

SON 62 37 1

OND 67 32 1

NDJ 69 29 2

DJF 64 33 3

JFM 55 41 4

FMA 43 52 5

MAM 30 63 7

ENSO

August 2021

CPC/IRI Early-Month Consensus ENSO Forecast 

Probabilities

(using NWS CPC classification system)

ENSO – Outlook

Neutral becoming La Nina this fall
Weather Outlook

August 2021

El Nino La Nina

North of Colorado - Dry and Warm 

South of Colorado - Wet and Cool 

North of Colorado - Wet and Cool 

South of Colorado - Dry and Warm 
Weather Outlook

August 2021

WPC 7-Day Precipitation Outlook

Accumulation period from Aug 24-31
Weather Outlook

August 2021

Temperature Precipitation

August – Outlook 
Weather Outlook

August 2021

Temperature Precipitation

Aug/Sep/Oct – Outlook
Weather Outlook

August 2021

Temperature Precipitation

Sep/Oct/Nov – Outlook
Weather Outlook

August 2021

Temperature Precipitation

Oct/Nov/Dec – Outlook
Weather Outlook

August 2021

Seasonal

Drought– Outlook
Navajo Operations Meeting

August 24th, 2021

Water Year 2021

Spring Runoff Review

Ashley Nielson

Senior Hydrologist

Colorado Basin River Forecast Center

National Weather Service/NOAA
Outline

● Water Year 2021 Summary

○ Precipitation

○ Snow

● 2021 April-July Observed Volumes

● Water Supply Forecast Performance

● Summary

● Contact Information
Precipitation: October-March

Basin Mean Precipitation as a % of Average 

San Juan 

River above 

Navajo 

Reservoir

Animas River

Oct-Mar 85 70

October 50 15

November 120 85

December 90 75

January 90 85

February 60 65

March 80 85

San Juan River
Precipitation: April-July

Basin Mean Precipitation as a % of Average 

San Juan 

River above 

Navajo 

Reservoir

Animas River

Oct-Mar 85 70

April 30 30

May 120 100

June 125 170

July 150 160

Oct-Jul 85 80

April May

June July
San Juan River above Navajo Reservoir Animas River Basin

Peak Snow: Below normal; 95% 

Peak Snow Timing: Early; ~2 weeks 

Melt out: Early

SNOTEL Snow Summary: Water Year 2021

Composite of NRCS 

SNOTEL sites

Composite of NRCS 

SNOTEL sites

April 1: 97% of normal

April 15: 74% of normal

Normal peak ~Apr 14

WY21 Peak SWE: Mar 29

Peak Snow: Below normal: 92% 

Peak Snow Timing: Early

Melt out: Early

WY21 Peak SWE: Mar 29

April 1: 88% of normal

April 15: 61% of normal

Normal peak ~Apr 7
CBRFC Model Snow Plots

Useful for tracking snow conditions:

-above SNOTEL sites

-after SNOTEL snow has melted out

Upper Zone >11,000’

Middle Zone

9,500’-11,000’

Lower Zone

<9,500’

CBRFC Model Snow: Animas-Durango

Normal Apr SWE: ~ 4 in 

2021 Apr SWE: 0.2 in

A significant storm on May 21 delivered widespread 

1.0-2.0+ inches of precipitation which resulted in 

rain at the lower elevations and additional snow 

accumulation above 11,000’. 
San Juan River Basin April-July Observed Volumes

April-July Unregulated Observed Volumes

Volume in 1000’s acre-feet / Percent of 1981-2010 average

San Juan-Bluff

499 / 45%

Vallecito

127 / 65%

Animas-Durango

211 / 51%

Navajo Reservoir

378 / 51%

San Juan- Farmington

502 / 46%

San Juan-Pagosa

134 / 62%

● April-July observed volumes ranged from 45-65% of average. 

Piedra-Arboles

101 / 51%

Rio Blanco-Pagosa

34 / 62%
Water Supply Forecast Evolution: Flaming Gorge Inflow

Apr-Jul Observed

Dry April

Forecasts were fairly steady until April 1. Forecasts decreased from April through mid-May due to below normal precipitation. Above normal 

precipitation during late May-July resulted in increases to the June and July forecasts. 

The observed April-July volumes fell within the forecasted range of possibilities suggesting the model was initialized correctly (soil moisture 

heading into the winter) and performed well through the season. 

Average 

Median

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

Late May/June Precip

395 kaf

53%

325 kaf

44%

335 kaf

46%

Water Supply Forecast Evolution: Navajo Reservoir Inflow

364 kaf

50%
Water Supply Forecast Evolution: The Monsoon is back! Flaming Gorge Inflow

July Precipitation: 2019-2021

August Precipitation: 2019-2021

2021 Water Year Streamflow
Summary

• Water Supply Conditions:

• April -July observed unregulated runoff volumes ranged from 45-65% of average.

■ Below normal snow conditions and early melt

■ Warm and dry April and early May

■ Late spring and summer precipitation helped improve water supply conditions

● Additional snow accumulation above 11,000’ in late May

● Increased runoff efficiency

● Lessened the impact of the dry antecedent soil moisture conditions

• Water Supply Forecasts

• Forecasts decreased between April and mid-May due to near record dry conditions

■ Low runoff efficiency in April due to very dry soils despite significant snowmelt 

• Forecasts increased in both June and July due to above normal precipitation

• CBRFC forecast model performed reasonably well this season

■ All forecast months (Jan-Jun) errors were better or similar to the historical model error

• July/August weather has brought precipitation and hydrologic relief to the region

• Improvements to baseflow and soil moisture conditions 
Contact Info

Contact Information

• Operational Hydrologist: in office

• 801-524-4004

• cbrfc.operations@noaa.gov

• Ashley Nielson - San Juan River 

Forecaster

• ashley.nielson@noaa.gov

• 801-524-5130 x333 CBRFC Webpage

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

CBRFC Water Supply Presentations

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

Water Supply 

(April-July)

Navajo: 378 kaf (51% avg)

Vallecito: 127 kaf (65% avg)

Lemon: 29 kaf (52% avg)

Animas: 211 kaf (51% avg)

McPhee: 84 kaf (29% avg)

Powell: 1,850 kaf (26% avg) 
CBRFC Water Supply Forecasts

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

Final

Water Supply 

(April-July)

Colorado 

River Basin

As of Jan, 2021


Reclamation Hydro Data 

https://www.usbr.gov/uc/water/hydrodata/reservoir_data/site_map.html https://www.usbr.gov/uc/water/hydrodata/reservoir_data/920/charts/pool_elevation.html
https://waterwatch.usgs.gov/index.php?id=wwdur_cumflow
Flow Goals 2021

2,500 cfs: 3 days

5,000 cfs: 0 days

8,000 cfs: 0 days

10,000 cfs: 0 days
July – August 2021 Events
Reclamation Teacup Diagrams

https://www.usbr.gov/uc/water/basin/index.html
Release will likely range between 

300 and and 800 cfs for remainder 

of WY 2021. 

Sept 30th Pool Elevation is expected 

to be between 6028 and 6031. 

Much depends on rain.


Based on current streamflow conditions, storage levels, and statistical 

outlooks based on 35 years of historical hydrology,

• Runoff projections range from 300kaf (42% avg) – 1,130 kaf (153% 

avg) with a median projection of 615 kaf (83% avg).

• 25% chance of prescribed spring peak release 

• 3% chance of falling below 5990 ft (min active storage)

• End of Water Year storage range 800 kaf (47% full) – 1,270 kaf (75% 

full) with a median projection of 1,210 kaf (71% full)

Projected Operations WY 2022
• The 30-year average used across agencies progresses every decade

• The currently used 1981 – 2010 time period for statistics will be 

updated to 1991 – 2020 soon.

• Navajo April – Juy Modified Unregulated Inflow averages:

• 1981 – 2010: 737 kaf

• 1991 – 2020: 628 kaf

• What does this mean? WY 2021 April – July inflow of 378 kaf

• 1981 – 2010: 51% average

• 1991 – 2020: 60% average

Statistical Average Update
• WY 2021 April-July runoff was poor throughout the San Juan River Basin. Navajo Modified 

Unregulated Inflow totaled 378 kaf which was 51% of average.

• There was no spring peak release. Releases varied from 300 – 900 cfs throughout WY 2021.

• Drought conditions have improved in the Four Corners due to rains but drought still persists and 

is still at its maximum D4 level in many places. Soil moisture has also improved due to rains.

• In November and December of 2021, releases are scheduled to increase in response to a continual 

declining dry hydrologic condition for the Colorado River system. This drought operation is 

implemented under the Upper Basin Drought Response Operations Agreement. The maximum 

flexibility within the Record of Decision will be used to release an additional 20,000 af on top of 

base releases. Notification of releases will occur prior to the scheduled release change.

• Based on current storage and streamflows and the statistical range of likely hydrologies for WY 

2022, there is a 25% chance for a spring peak release. The median runoff forecast is for 83% of 

average.

• The statistical “average” range will soon be migrated from 1981 – 2010 to the 1991 – 2020. 

Summary Next Meeting January 18th 2022
Reclamation Contacts:

Marc Miller – Water Management Group Chief

970-385-6541 mbmiller@usbr.gov

Susan Novak Behery – Hydrologic Engineer

970-385-6560 sbehery@usbr.gov

To be added to Navajo Dam notices email list, send an email to 

westcoloareaoffice@usbr.gov 

Useful Links

Reclamation: www.usbr.gov/uc

USGS: water.usgs.gov/nwis

CBRFC: cbrfc.noaa.gov