Residents of the Chester and Lake Almanor area know the level of Pacific Gas and Electric Co.’s major hydroelectric reservoir fluctuates with the season. Phil Datner knows precisely how much — and when.
Datner, a retired electronic technician, has been paying attention to Lake Almanor’s ebb and flow since 2015. When he moved to Hamilton Branch, he was immediately intrigued by the many sensors gauging water level, stream flow and more. He began volunteering with the California Department of Water Resources, taking measurements of Lake Almanor for the Sierra Institute for Community and Environment. That gave him enough familiarity with the system to start downloading daily and hourly data recording reservoir levels from DWR websites that publish lake and reservoir levels throughout the state of California.
“I wanted to see what is what,” Datner told The Plumas Sun. And he began turning what he saw into line graphs. “People can see the information better on a graph.”
The results are multicolored strands undulating across a white background. The combination presents a decade of data about California’s eighth-largest reservoir.
Lake Almanor’s water level generally fluctuates between 4,476 and 4,494 feet in elevation. PG&E keeps the vacillation within about 18 feet, Datner said. When it leaves the reservoir, the water ends up in Lake Oroville, which DWR controls as part of the State Water Project. In addition to using water to generate electricity, PG&E has downstream obligations that include the sale of water and maintaining legal amounts for fish and other wildlife.
The data so far this hydrological year, which started Oct. 1, 2023, show 10 to 14 inches of precipitation. That’s about normal, Datner said. Temperatures are averaging around 5 degrees higher than those in an average year, from a high of 45 degrees Fahrenheit to a low of 30 F. He attributes this to a lack of snow at Almanor’s 4,500-foot elevation. If this trend continues, spring runoff could start later due to less snowpack at lower elevations, he said.
Datner, who said he likes to see how things can change over time, is not finding major fluctuations in water levels at the reservoir. “Lake Almanor is a man-made lake, used for man-made reasons,” he said. “Things don’t change that much.”
If the unanticipated were to occur, Datner’s graphs would reflect it. Expect erratic lines varying wildly from the gentle curve of an average year. For now, he said, lake level trends are normal.
But note well: Datner also graphs earthquake activity.