It was past midnight when Lester McKee pulled the plug. He’d been watching the weather for days on screen, looking for the perfect storm of conditions he needed to send his team out to sample the Guadalupe River in Santa Clara County. He knew there’d been enough rain already to saturate the soil and surpass annual averages. Zooming in on real-time sensors aimed at Santa Clara Valley Water District reservoirs, he could see they were full enough to spill downstream. On NOAA’s weather site, he found that ten inches of rain were projected to fall on the ridgeline of the Santa Cruz Mountains, and the state’s water resources department was estimating peak flows of 9,000 cubic feet per second in the river. The intensity of storm also looked promising, exceeding two inches of rain in a six-hour period right over the middle of the watershed.
“I could see it was going to be what I call a hot moment, when the watershed gets enough rainfall that its mean side comes out,” says McKee, an environmental scientist with the San Francisco Estuary Institute.