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Winter/Spring 2024 Columbia Basin Water Supply Forecast

by Kyle Dittmer, CRITFC Hydrologist-Meteorologist

We measure water years from October to September. Starting on Oct. 1, the 2024 water year had a dry start, continuing into November. A big change started in early December as a series of powerful atmospheric river events (formally known as the “Pineapple Express”) delivered much-needed valley rainfall and mountain snowfall. These special weather events continued through January.

The seasonal rain/snow accumulation graphic (right) shows higher than normal totals in southern Idaho and Oregon’s Willamette Valley. This pattern has greatly benefited from the recent powerful storms rich in moisture.

At present we are in a moderate-strong “El Niño” event where Pacific Northwest winters are warmer than normal temperature with below normal rain/snowfall. This means that the amount of spring snowmelt runoff will be moderately below normal. NOAA weather forecasters predict that this El Niño event will weaken and transition to a neutral state by spring. NOAA forecasters are now predicting, with a 75% chance, that we will move back into a La Niña pattern next winter (very beneficial for Columbia River salmon).

The timing of the river runoff is likely to be near historic norms: late-April to mid-to-late May for the tributaries and late May for the mainstem Snake and Columbia rivers. This runoff feeds the river flow which helps the fish migrate down the river and out to the ocean. Unfortunately North Pacific Ocean conditions along the Pacific Northwest and Alaska coastlines are less favorable for salmon survival now due to less coastal upwelling from the deep ocean. The upwelling signal is beginning to increase.

There is still concern of the lingering effects of the multi-year drought (see graphic below). Any existing dry soils will need to be replenished before any snowmelt runoff may occur. This means that the expected tributary river runoff may be a little lower than expected in some areas.


The table below shows the change in snowpack, as measured by “Snow Water Equivalent” (i.e., the liquid water content of the snow) for select tributaries that are of interest to tribal fishery program managers:

The change from January 1 to February 1 is extreme due to the benefit of the atmospheric river events. The March 1 update has benefited from more mountain snowstorms.

The figure (see graphic below) shows the current state of the region’s snowpack. The Oregon Cascades and southern Idaho showed the most improvement. Current North Oregon Cascades snow level is at 1800 feet. We are three-quarters of the way in the seasonal accumulation of PNW snowpack.

Snowpack, along with monthly and seasonal precipitation and current river flow, are the key components that are used to calculate the seasonal Water Supply Forecast. This forecast is used by water management agencies – U.S. Army Corps of Engineers, BPA, and the U.S. Bureau of Reclamation – to determine how much water is released for power, irrigation, and fish. The latest water supply forecast (as of March 11): Columbia River at The Dalles is 91% of normal for the April-July runoff period (CRITFC method). NOAA’s forecast is for 78% of normal.

(maps provided by NOAA/National Weather Service-Portland, updated on 11-March-2024)


If you have any fishing enforcement problems or need assistance or information, day or night, contact the Columbia River Inter-Tribal Fisheries Enforcement Office, 4270 Westcliff Drive, Hood River, Oregon. Phone: (541)-386-6363 or toll-free (800)-487-FISH (3474). Show pride in your tribe’s treaty rights by carrying your tribal ID. Please consult your tribal Fisheries Department for additional details on tribal regulations. PLEASE WEAR YOUR LIFE JACKETS FOR SAFETY and avoid overloading your boats.


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