Thursday September 12, 2024
Lake County Record-Bee —
As we move into the fall months a number of people are curious about how far down Yolo County can draw the lake. The lake level is currently at 3.6 feet on the Rumsey Gauge. Clear Lake historically reaches its lowest level during the months of October and November.
Yolo County can take the lake level down to a plus-1 foot on the Rumsey Gauge. The Rumsey Gauge is a measurement of the lake level that was established back in 1872 when Capt. Rumsey created a gauge to measure the various lake levels. He came up with a standard that is still used today.
Rumsey decided that when water ceased to flow over the Grigsby Riffle, the lake would be at zero on his gauge. Zero Rumsey is equal to a height of 1318.256 feet above sea level. When water was above the riffle it would be called plus Rumsey, such as 1 foot, 2 feet and so on. Below the riffle, the lake level would be measured as minus Rumsey.
All measurements were based on zero Rumsey at the Grigsby Riffle, which is located on Cache Creek, about two miles from the dam. Yolo County was originally allowed to take the lake level down to zero on the Rumsey Gauge, however in 1978, eight years after Indian Valley Reservoir was built, Yolo County made an agreement with Lake County to stop taking water out of Clear Lake at plus-1 foot on the Rumsey Gauge.