California is having its rainiest water year since record-keeping began in 1895 — a deluge that has been rapidly altering the landscape of a state that until recently was in drought. It has rained an average of 27.81 inches statewide from Oct. 1 to Feb. 28, the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information reported. A water year begins on Oct. 1. The 20th century average was 15.5 inches in the same time period, and the previous record was the winter of 1968-69, when it rained an average of 27.34 inches, the agency reported. Signs of this shift are everywhere.