Only 5 more inches. That’s the amount of precipitation the northern stretch of the Sierra Nevada needs between now and September 30 to become the wettest water year on record. The Eight-Station Index, a measure of precipitation in the northern Sierra that helps determine the status of Northern California’s water supply, currently stands at 83.5 inches. It’s only another storm or two away from the current record of 88.5 that was hit in the 1982–83 season.