Water supply gets boost to start 2021

By KARL HOLAPPA staff writer

An atmospheric river of precipitation has helped the Yakima Basin increase its water supply in January, making up for some shortages and starting 2021 off strong.

According to the Jan. 14 Yakima Project Hydromet System Status Report, Lake Keechelus is at 52% capacity, with Lake Kachess coming in at 59% and Lake Cle Elum at 41%. Total capacity for all five reservoirs in the system is at 50%, putting total storage at 108% of average to date.

The report states that inflow to the five reservoirs is 194% of average, and much of that can be attributed to the strong precipitation in January. Precipitation at the five reservoirs from Jan. 1 to Jan. 14 was 33.65 inches, a whopping 218% of average and 85% of the months average. Precipitation for the water year to date is 135.30 inches, or 110% of average. Snowpack in the basin has also been affected by the atmospheric river, with NRCS Snotel SWE for the Upper Yakima Basin reporting 127% of average.

Current Yakima Subbasin forecasts place Lake Keechelus at 101% of average, Kachess at 103% and Cle Elum also at 103%, with the system as a whole coming in at 102% forecast of average.

Current Yakima Basin storage sits at 492,470 acre-feet, putting it on par for water years 2005 and 2017, and if weather predictions are accurate, the year could continue to improve through the winter. According to the January Bureau of Reclamation River Operations presentation, winter and spring seasons in the basin are predicted to have below average temperatures and above average precipitation. The bureau’s prediction states that La Niña is likely to continue through the Northern Hemisphere winter, with a 95% chance between January and March and into spring with a potential transition into spring, with 50% chance of neutral from April to June.

“The La Niña mode is likely to kick in during January thru April, and that opens the door to more active weather, but also colder air from the Gulf and coming down from the North,” Meteorologist Phil Volker of Extended Range Forecasting said in the presentation. “We have had late season snows the last several years, and it appears that potential is facing us again.”

The BOR hydrologist said the favorable conditions have resulted in healthy storage levels in the five basin reservoirs and said the La Niña conditions give forecasters a reason to be optimistic about the water supply going forward.

“As wet as it’s been and as good as it’s been for refill and the snowpack, the November and December percents of average were I think 85% and 90%,” he said. “It’s an interesting combination that even though they weren’t up to average, we did have a wet October that’s helped us along, carried us forward and really wetted up the ground. We’ve just had a good combination of weather, given that we were below average those two months. We have snowpack on the ground, and we have our reservoirs filling at the same time. I think it goes to show that if you get somewhere close to average, over 90%, we’re pretty good if we’re not digging out a big hole from the previous season.”