What happens to spring runoff in the weeks after peak snowpack? Colorado scientists are trying to find out.
Water managers in the Colorado River basin are gaining a better understanding that what happens in the weeks after peak snowpack — not just how much snow accumulated over the winter — can have an outsize influence on the year’s water supply. Water year 2021 was historically bad, with an upper basin snowpack that peaked around 90% of average but translated to only 36% of average runoff into Lake Powell, according to the U.S. Bureau of Reclamation. It was the second-worst runoff on record after 2002. One of the culprits was exceptionally thirsty soils from 2020’s hot and dry summer and fall, which soaked up snowmelt before runoff made it to streams. … But according to the paper, in 2021, “rates of snowmelt throughout April were alarming and quickly worsened summer runoff outlooks which underscores that 1 April may no longer be a reliable benchmark for western water supply.”
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