Record-breaking temperatures scorched the Pacific Northwest in June as a heat dome settled over the region. While heat domes – a mass of high-pressure air that acts like a lid trapping heat – aren’t unusual, the magnitude and intensity of this one was unprecedented, causing temperatures to spike well into the triple digits from Vancouver, British Columbia to Portland, Oregon.
This was the just the latest example of the dry conditions throughout the West. According to the U.S. Drought Monitor, almost 80 percent of the region is in a drought. At its July meeting, the Council was updated on the basin’s water supply from Ryan Lucas with the Northwest River Forecast Center and Aaron Marshall with the U.S. Army Corps of Engineers.
While at the end of February much of the Columbia Basin had near to above normal water supply forecasts, the Snake Basin forecast was mostly below normal, and the Middle Snake tributaries water supply forecasts were especially low. Despite the healthy buildup of snow in the northern Cascades and upper Columbia Basin, starting in March, very dry conditions had reduced water supply forecasts throughout the region. Currently, the only basins with normal April – September forecasts are in the Clark Fork and portions of the Washington Cascades.
Many measurement locations throughout the basin have forecasts that rank as some of the driest volumes documented, noted Lucas.
“If these forecasts prove accurate, it will be the driest April – September volume on record.”
And it’s a recipe for disaster for fish as flows are well below normal and stream temperatures are increasing. Fisheries managers are evaluating conditions in the mainstem Columbia and Snake rivers and tributaries, and initiating emergency management actions where needed, including moving fish to avoid warm water, altering hatchery operations, and modifying harvest regulations.
“We may be experiencing another exceedingly hot, dry season like the one we experienced in 2015,” noted Fish and Wildlife Director Patty O’Toole. “We’ve been through this before, and we’ll be working with our partners to implement actions to mitigate another challenging summer.”