Here’s the summer rumor, cleaned up for daylight: “Pacific Gas and Electric Co. (PG&E) is draining Lake Pillsbury, so the upper river’s toast.” Catchy, dramatic and not quite right. What’s really happening is more boring and more important — the Federal Energy Regulatory Commission (FERC) greenlighted a summer operating tweak that keeps Lake Pillsbury low (for dam safety and fish), which throttles the Eel River-to-Russian River diversion to a trickle. That means the upper Russian River has less late-summer help from the tunnel. Not nothing — just less.
The fine print: Regulators approved minimum flows this summer of 25 cubic feet per second (cfs) through the Potter Valley tunnel (the diversion from the Eel River to the Russian River), with authority to drop as low as 5 cfs if the Eel River warms up or storage slides. Below Scott Dam on the Eel River, the floor is 20 cfs. The order also sets tripwires: If Lake Pillsbury nears a critical 12,000 acre-feet (a standard measure of water volume), the tunnel can be pinched further; if storage climbs past 36,000 acre-feet after Oct. 1, the variance wraps. All of this sits on top of a standing safety restriction that has already lopped roughly 20,000 acre-feet off how full Lake Pillsbury can run. That’s the “why it looks low” part — not a secret drain-the-lake scheme.
Meanwhile, Sonoma Water (the Sonoma County Water Agency) asked the California State Water Resources Control Board (State Water Board) to modernize how summer flows are set on the Russian River. Instead of using an old Eel River index, the 2025 order keys decisions to what really matters for the upper river: storage in Lake Mendocino. It also trims the summertime minimums to 125 cfs in the upper Russian and 70 cfs in the lower so we don’t burn through reservoirs defending a number on paper. A helpful passage in that order reminds everyone of a hard truth in California water law: When flows are mostly stored water, many diverters can’t legally take it under their own rights. Cities operating under Sonoma Water’s permits can, but most private rights can’t. That’s why this feels different upstream…