Water Supply in Good Shape for Summer

All indications point towards a very favorable water supply for the summer. Reservoirs are filled to the brim west of the Cascades and are above-average east of the Cascades, and the entire Pacific Northwest has above-average snowpack, including the Upper Columbia and Snake River Basins in British Columbia and Idaho/Eastern Oregon. Our snowpack got off to very slow start and was well-below-average through early January, but it increased dramatically during the second week of January as much colder and wetter/snowier weather entered the Pacific Northwest, and higher elevations continued to see snow build through the latter half of January as we remained in a wetter-than-average pattern. The atmospheric river that brought major flooding to the Cascades and record flooding to the Blue Mountains significantly reduced our snowpack below 3,500 feet but we saw dramatic gains above 6,000–7,000 feet and moderate gains overall, and a few chilly storms in the latter half of February helped restore our lower-elevation snowfall after the heavy rain washed it all away.

Having a bountiful water supply is beneficial for many reasons. Power costs are cheaper due to higher streamflows through the dams and less need to run expensive fossil fuel plants, and a higher water supply reduces the risk of municipalities having to impose water rations for their citizens. To my knowledge, it does not affect the price of agriculture—water bills are regulated at a fixed price regardless of supply, and rations have never been imposed on farmers.

But while cheaper utility bills and green lawns are nice, a good water supply can mean the difference between life or death for creatures that rely on ample summer streamflows and lake levels to survive. And nobody benefits more from a healthy water supply than the salmon that return to our rivers in the early autumn. After a hot summer and poor water year, streams are very low and warm just as the salmon are returning to spawn. Warm water can hold less oxygen and increases a salmon’s susceptibility to disease, so pre-spawning mortality rates (when the salmon make it up the river but die before spawning) skyrocket when temperatures are well-above-average, particularly when they approach approximately 20 degrees Celsius. In fact, Oregon governor Kate Brown recently wrote a letter to Jay Inslee calling for the removal of four Snake River dams, as these dams are resulting in significant salmon mortality by increasing water temperatures in the reservoirs behind them. I won’t get into that debate here, but it just underscores how important high, cool rivers are for salmon to successfully spawn.

If we see a very warm and dry spring, we may end up with a slightly below-average water supply for summer, but given how widespread the above-average snowpack and reservoir levels are throughout the Pacific Northwest, I think it’s a pretty safe bet that we’ll have at least an average water supply this summer. Additionally, March and April can still be very snowy months even between 3,000–4,000 feet, and our region wide snowpack doesn’t typically peak until May.

Unfortunately, a healthy snowpack is not correlated with reduced fire danger. If anything, a wet spring increases summer fire danger because it results in increased low-level vegetation, providing more fuel for fires when this vegetation dries in the summer. It’s too early to know how the 2020 fire season will turn out, but we can at least celebrate the high probability of an above-average water supply for the summer, both for our pocketbooks and for our beloved salmon!

~Charlie Phillips

Charlie Phillips, a Madrona resident, received his B.S. in atmospheric sciences from the University of Washington and works in Portland as a meteorologist. Check out his weather website at to charlie.weathertogether.net.

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