On a normal day, Ullrich Water Treatment Plant produces roughly half of Austin's drinkable water and is crucial to keeping the city's water system functioning. State regulations require the plant to either have access to a backup power source or a substantial amount of water reserves in case the plant sees an unexpected shutdown. Ullrich has both. So when a tree limb fell on an electric line leading to a substation that powered Austin's largest water treatment plant on Feb. 17, backups should have snapped into place to keep power running and water production churning. But there was a problem: Nobody on site knew how to operate a 52-year-old gear switch that would have restored power to the plant.