Navajo Unit Operations

August 21st, 2019

Coordination Meeting
WY 2019 Summary

• Snowpack peaked at 144% of average

• A maintenance release peaking at 5,000 cfs was conducted in 

June. Volume released over base was 85kaf. When combined 

with Animas River, flow targets for ESA species achieved.

• Final April-July inflow volume 1,162,400 af (158% avg)

• SJRIP request for increased baseflows to move excess water. 

(Navajo Operations ROD, 2006. Adaptive management component of SJRIP Flow 

Recommendations, 1999, revised 2018)
REVIEW 

OF WY 2019 

OPERATIONS
2019: Snow above Navajo peaked at 144% of average (29.9 in. SWE)
2019: Forecasts increased throughout the season



Flow Goal (cfs) Goal Days Total Days

2500 10 80

5000 25 52

8000 10 9

10000 5 6
Scour Measurement Stations 

San Juan River 

Date

Archuleta 

Gage Flow 

(cfs)

Archuleta 

Gage Stage 

(ft)

10/04/2018 500 3.12

6/22/2019 500 3.09

8/26/2018 830 3.65

7/9/2019 830 3.58
WEATHER AND FLOW 

FORECASTS

Greg Smith Sr. 

Hydrologist Colorado 

Basin River Forecast 

Center
Characteristics of 2019 runoff season

Largest challenges of 2019 runoff season

Forecast performance / verification

Final thoughts . . .

Greg Smith – Sr. Hydrologist

Colorado Basin River Forecast Center

Navajo Unit Coordination Meeting

Aug 21 2019

Farmington, New Mexico
Below average precipitation through 

December.

Snowpack was below average to start 

the season ~65-70% of normal along 

with dry soils.

Here we go again ?

Feb 2019 Mar 2019 May 2019

205 % of Average 220 % of Average 205 % of Average

75-80% of average

Oct – Dec 2018

San Juan Basin: A slow start before an amazing turn around
San Juan Basin: February-March precipitation ranked among the highest on record 
Persistent trough of low pressure was located over the western U.S.

Multiple storm systems moved eastward through the Colorado River Basin.

Several storms had a sub tropical moisture source that resulted in significant precipitation

Mean upper atmospheric pattern for February 

shows the strong trough over the Colorado and 

Great Basins.

The winter / spring weather pattern

Early April satellite image showing another storm 

system with a sub-tropical moisture tap. Several 

inches of precipitation resulted from this system.
May / June 2019 – Warm Up Already ! 

Persistent cool / wet weather - delayed Snowmelt (occasional snowfall high elevations)
Snow Ranking as of June 6th 2019 Black is highest for this time of year

Blue is 2nd or 3rd highest for this time of year

Normal

2019
Peak runoff a little later than usual with much above average runoff extending through July

Extended period 

of higher than 

normal flows

Normal time 

of peak
Extended period of 

higher than normal flows

Peak timing was within the normal time frame but high flows extended through June 
Forecast Challenges: How would dry soils impact overall runoff volumes ?

Very dry soils entering the winter season

The Questions:

Would a slower melt result in lower 

volumes overall?

Is there enough snow to overcome 

soil moisture deficits?
Forecast Challenges: Large snowpack (as a percent of normal) at lower elevations
May 14th guidance looking ahead to May 24th

Forecast Challenges: 

Different scenarios in meteorological guidance (Impacting Animas peak flow lead time) 
Forecast Challenges: Wide temperature variations and impacts to snowmelt pattern

Observed temperatures May 2nd – June 10th – Wolf Creek Summit – 11,000 feet 

freezing
Hydrologic Model 

Simulated streamflow

Observed gage 

reading

Forecast Challenges: Observed data issues (not uncommon especially in high years)

Hydrologic Model 

Simulated streamflow

Observed gage 

reading after 

adjustment

Daily Operations:

We often see a discrepancy between an 

observed reading and our model simulation.

The Decision:

Is a model state incorrect or might something in 

the stream be impacting readings (debris, scour, 

etc.)

In this case upstream and downstream readings 

were close to model simulation suggested some 

issue at the gage.

Eventually a field measurement was made and 

the gage readings adjusted, validating the model 

performance. 

The decision to be patient and not adjust model 

states to lower values was correct.

This result is not always the case however, 

especially in data sparse areas and when the 

gage reading was indeed accurate.
April-July runoff volume was 158% of average

June-July runoff volume was the 3rd highest in 49 years of record. Last year was 2nd lowest.

Increases again due to a wet May, 

probably underdone in the model.

10%

50%

90% Significant increase 

in guidance due to 

wet conditions

Forecast Performance: 2019 Forecast Evolution Plot Navajo Reservoir

Significant snowpack and cool / wet weather resulted in a late snow melt

Snow at lower elevations contributed this year, in most years it’s melted out by April

Below average runoff early gave way to efficient snow melt and high runoff conditions late

Observed volume 

running slightly 

below normal 

accumulation in April.
Large errors early (expected). Model caught up some but wasn’t stellar in performance

Extreme years are challenging, the model tends to over-forecast very low years and under-forecast very high years

This year was no different. Forecasts assume average conditions in the future. The pattern was very wet and cold.

Forecasts error this year were greater than the historical mean absolute error in every month (April-June).

Observed volume was not forecast at the 10% probability level until mid March. (May precipitation top 5-10% of record)

Soil Moisture deficits in higher elevations of the model were significant, likely too much to overcome.

May precipitation inputs into the model (particularly high elevation snow gains) may have been too little.

Overall model snow estimates, particularly in the eastern headwaters, were somewhat underdone.

Under-forecast

Over-forecast

Forecast Performance: Navajo Reservoir Inflow 

Under-forecast

Over-forecast
Runoff volume of 320 KAF / 165 % of average was 2nd highest in 78 years. Last year 3rd lowest

Increases due to very 

wet conditions

Observed inflow 

running below normal 

accumulation in early 

April and May.

Model was too low on the snowpack at higher elevations, greater contribution from lower elevation snow

Below normal inflow in early April and below average precipitation resulted lower guidance

Similar condition occurred in May resulting in a slight decrease between May 1st and May 15th

Forecast Performance: 2019 Forecast Evolution Plot Vallecito Reservoir

Late season runoff 

was very efficient
Large errors early in season that carried into spring

Somewhat expected with very wet conditions that developed after forecast dates

Errors were larger (as a percentage) compared to the Navajo inflow forecast

The model took longer to forecast the observed value at the lower probability levels (i.e. 10% exceedance)

Similar snow and soil moisture issues but potentially greater impacts from low snow model states

May precipitation was the 2nd / 3rd highest on record – Did enough precipitation make it into the model?

Model soil moisture deficits may have continued to have too large of an impact

Under-forecast

Over-forecast

Forecast Performance: Vallecito Reservoir Inflow 

Under-forecast

Over-forecast
Forecast Performance: 

Day to day forecasts indicated too quick of a seasonal recession

Daily Vallecito Inflow Forecast

Combination of: 

Model running out of snow too quickly 

Summer rain events increased flows (an indication of saturated soils)

Similar situation with the Lemon inflow forecasts
Forecast Performance: Vallecito Forecast Segment Model Snow States 

Forecaster snow 

state adjustments

(increases)
Despite playing catch up with the forecasts it was a very beneficial year on the heels of a 

disastrous 2018.

Communication success with Reclamation and other stakeholders reached a new plateau. We 

processed a lot of information, talked daily, tried to identify shortcomings in the forecast (daily and 

monthly) in a timely manner. Timing for the Animas peak was reasonable.

Model performance was not optimal regarding the volumes. However years like this allow us to 

identify limitations and provide an opportunity to improve performance (you don’t learn much from 

an average well behaved year).

For 2019 these Include:

Soil moisture deficits at high elevations were perhaps too large to overcome

Not enough precipitation / snow gain in May at higher elevations

Overall the snow as underdone in the model at higher elevations (less so in the Animas)

Contribution from lower elevation snow more significant than model anticipated

Record snow existed in early June, another extreme situation for the model

Heading into Fall:

ENSO Neutral conditions expected fall / winter - No strong climate signal

Northern Jet seems strong / active for this time of year

Summary
It’s time for the next chapter ...

Meeting with you all to solve the annual runoff puzzle...

The value of the communication we’ve established ...

Data ! ....

Thank You !
CBRFC 2020 Water Supply Contacts

Ashley Nielson – San Juan, Gunnison, Dolores, Lake Powell Focal Point

ashley.nielson@noaa.gov

Brenda Alcorn– Upper Green River Basin, Yampa, Duchesne Focal Point

brenda.alcorn@noaa.gov

Cody Moser – Upper Colorado Mainstem Focal Point

cody.moser@noaa.gov

Tracy Cox - Lower Green (San Rafael & Price) River Basin Focal Point

tracy.cox@noaa.gov

Zach Finch - Lower Colorado Basin, Virgin Basin Focal Point

zach.finch@noaa.gov

Brent Bernard – Six Creeks, Provo , Sevier Focal Point

brent.bernard@noaa.gov

Patrick Kormos – Bear, Weber Basin Focal Point

patrick.kormos@noaa.gov

Michelle Stokes – Hydrologist In Charge

michelle.stokes@noaa.gov

Paul Miller– Service Coordination Hydrologist

paul.miller@noaa.gov
PLAN FOR 

WY 2020 

OPERATIONS
Summer Baseflows

For the summer of 2019, the San Juan River Basin Recovery 

Implementation Program has recommended a target base flow 

of 1,500 cfs through the critical habitat area. The target base 

flow is calculated as the weekly average of gaged flows 

throughout the critical habitat area from Farmington to Lake 

Powell. Reclamation will attempt to maintain this augmented 

baseflow as long as water is available over the end of water year 

storage target (a reservoir elevation of 6063 ft). 

Based on current conditions and flow forecasts, which are for 

warm dry weather, high releases (1,000-1,500 cfs) are expected 

from the dam through the first two weeks of September, after 

which the release will most likely be decreased back below 1000 

cfs. 



SJRIP FLOW RECOMMENDATIONS

DECISION TREE
Navajo Dam Operations 

Governing Documents 

• Record of Decision for the Navajo Reservoir Operations, 

Navajo Unit – San Juan River New Mexico, Colorado, 

Utah Final Environmental Impact Statement 

(Reclamation, 2006)

– Flow Recommendations for the San Juan River (San Juan River 

Basin Recovery Implementation Program, 1999, revised 2018)

– Recommendations for San Juan River Operations and 

Administration for 2017 – 2020 (Collectively known as “The 

Shortage Sharing Agreement)

• Navajo Dam and Reservoir San Juan River Water 

Control Manual (US Army Corps of Engineers, 1970, 

revised 2011)
https://www.fws.gov/southwest/sjrip/pdf/DOC_San_Juan_Dam_Modified_FlowProcedures_2018.pdf
Maintenance Releases

• Maintenance Releases are not currently part of 

the SJRIP Decision Tree.

• Reclamation Operation designed for channel 

maintenance and to support Navajo’s 

Authorized Purposes.

• Short release designed primarily to mobilize 

sediment, push back channel encroachment.

• Maintenance releases are still timed like a 

regular spring peak release in an effort to meet 

flow goals.

Technical Report SRH-2016-33, Reclamation

San Juan River Channel Processes and Flow Conveyance below 

Navajo Dam, NM (2016)
OTHER 

AREA 

PROJECTS
Major San Juan River Basin Reservoirs

(8/19/2019)

Total deficit = 3654 af

Natural basin inflow volume = 1917 af

Total volume pumped for 2019 = 1737 af
MAINTENANCE 

UPDATES
Maintenance Updates...

• Rehab jobs of 72” Hollow Jets and 30” 

Hollow Jet are complete.

• Working with NMDOT to repair fences for 

spillway and address issues of oversized 

loads going over the spillway bridge.

• New gravel on parking lot on top of dam 

and new pavement in the turnaround area.
SJRIP 

UPDATE
Summary

WY 2019 Summary

• Snowpack peaked at 144% of average

• A maintenance release peaking at 5,000 cfs was conducted in June. Volume 

released over base was 85kaf. When combined with Animas River, flow targets 

for ESA species achieved.

• Final April-July inflow volume 1,162,400 af (158% avg)

• SJRIP Request for increased baseflows to move excess water. 

• Releases now through Sept will likely range between 800 and 1500 cfs.

• September – October, releases will likely be 1000 cfs or less. 

• First two weeks of November, the release will drop as low as needed to 

make the lowest baseflow (as low as 250 cfs). 

• After mid-November, operations will resume as normal and releases will 

range between 350 and 650 cfs on average. 
NEXT 

OPERATIONS 

MEETING:

Tuesday, 

January 21st, 

2020
UPDATES 

FROM OTHER 

AGENCIES
How You Can 

Access Information

Bureau of Reclamation

www.usbr.gov/uc

USGS

http://water.usgs.gov/nwis

Colorado Basin River Forecast Center

www.cbrfc.noaa.gov
For Operations Updates

• EMAIL UPDATES

• to be added, email rswickard@usbr.gov

• WEBSITE

• Navajo Reservoir:

http://www.usbr.gov/uc/wcao/water/rsvrs/notice/nav_rel.html

• All UC Operations

https://www.usbr.gov/uc/water/index.html

• PHONE

• Susan Behery 970-385-6560 

• WCAO Main Office 970-385-6500
Reclamation Contacts:

Marc Miller

970-385-6541 mbmiller@usbr.gov

Susan Novak Behery

970-385-6560 sbehery@usbr.gov 

Ruth Swickard

970-385-6523 rswickard@usbr.gov