October brought with it Colorado’s first significant snowfall of the season, leaving the Arkansas River Basin’s snow totals at 94% of the median (figure 1; figure 2). Some areas of the basin have yet to see their first snow. Average first snowfall dates vary greatly across the Arkansas River Basin, but the timing of these first snow events generally follows recent trends in temperature in Colorado, where the falls have gotten a lot warmer, but the springs haven’t warmed nearly as much, reported the Colorado Climate Center (figure 3; figure 4).

figure 1: Snow Water Equivalent in the Arkansas River Basin

figure 2: October Snow Water Equivalent Compared to Median

figure 3: “First snow in Colorado”- Colorado Climate Blog (source)

figure 4: “First snow in Colorado”- Colorado Climate Blog (source)

According to the most recent U.S, Drought Monitor, most of the Arkansas River Basin is abnormally dry or drought free, with moderate or severe drought only along the Kansas-Colorado (figure 5). In general, recent drought reports indicate that western Colorado has seen less severe drought conditions, and eastern Colorado has seen more server drought.

figure 5: US Drought Monitor (10/31/2024)

The National Weather Service’s Three Month Outlook is predicting that there will likely be above-normal temperatures and leaning towards a warmer/drier conditions in the Arkansas River basin through January (figure 6; figure 7). These models are based on a predicted shift to La Niña. As of now, the National Weather Service Climate Prediction Center reports that La Niña is favored to emerge in September-November (60% chance) and is expected to persist through January-March 2025. During La Niña cycles, Colorado typically sees dry falls and snowy winters. 

figure 7: Three Month Precipitation Outlook

Monthly Precipitation Totals

figure 8: USDA’s Arkansas River Basin SNOTEL Snow/Precipitation Update Report

Flows Compared to Median

*30 year running avg

River Flow Snapshot (10/31/2024,12:00pm)*

* measured flow totals include native flows, BOR project water, releases, and exchanges
​

• Granite, CO (8 miles south of Leadville)-  98.8 cfs
• Salida, CO- 372 cfs
• Wellsville, CO- 421 cfs
• Portland, CO (10 miles south of Canon City)- 422 cfs
• Above Pueblo Reservoir, CO- 422 cfs
• Avondale, CO- 443 cfs
• Lamar, CO- 22.1 cfs

For current streamflow updates, reference the Colors of Water webpage.

Monitoring

Drought Monitoring: US Drought Monitor

Drought Forecast: National Weather Service Climate Prediction Center

Precipitation Totals:  Community Collaborative Ran, Snow, and Hail Network’s Precipitation Mapping System.

Snowpack: Natural Resources Conservation Service

Winter Water Storage System (only applicable until march): Southeastern Colorado Water Conservancy District

Precipitation: ​​https://www.cocorahs.org/

Arkansas River Daily Report – http://www.div2waterops.com/dailyreports

Wind: Windy

 Snow Survey and Water Supply Forecasting: Natural Resource Conservation Service Snow Survey

Additional monitoring resources: 

Colorado Water Conservation District/Department of Natural Resources

 Colors of Water 

USBR Instant Data Hydromet

Definitions

30 Year Running Average:  When we present the monthly flows, we compare them to that month’s median flows from the last 30 years (referred to as 30 year running average). 

Reservoir Percent Full: The  Bureau of Reclamation considers a reservoir “full” when pool elevation is at the top of the active conservation pool. Percentage is therefore based on total reservoir volume below that level.

Authorized Diversion: An authorized diversion is NOT A CALL, but a notice that one (or more) diversion structures are subject to a call have been authorized to divert water against the call. These types of  diversions are only authorized when the diversion will not affect the downstream call. This type of diversion could occur due to a localized event, such as precipitation diurnal patterns (labeled futile diversion or localized event)

Nonconsumptive call: A call by a diversion that consumes no water (ex. Hydropower, in-stream flow water management).

Futile Call: A situation in which a junior water right holder is allowed to continue to divert in spite of a downstream senior call when curtailing the junior would not produce any additional water for the senior. 

For more information on calls, reference the Colorado Division of Natural Resources Administrative Call Standard document. 

Educational Resources

Administrative Call Explained: DWR

Citizen’s Guide to Colorado Water Law: CFWE Education

Non-Attorney’s Guidebook to Colorado Water Courts: Co State

Voluntary Flow Management 

1. https://arkvalleyvoice.com/ahra-says-arkansas-river-flows-are-high-and-fast-making-safety-paramount/
2. https://coloradotu.org/arkansas-river

U.S. Climate Normals: https://www.ncei.noaa.gov/products/land-based-station/us-climate-normals 

figure 5: Three month precipitation outlook