Sonoma Water asks the state to lower Russian River minimum flows for 2027

By The Downspout · Posted Oct 12, 2026 · 2 min read

Sonoma Water has asked the State Water Board to lower the Russian River's minimum flows in Normal years starting May 1, 2027. This is a proposal, and the documents we read show no decision yet.

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What happened

Sonoma Water filed a petition with the State Water Board on August 28, 2026. It asks for a temporary urgency change to four of its water right permits.

The petition has two parts.

Starting November 16, 2026, for 180 days, decide if a year is Normal, Dry or Critical by how much water is in Lake Mendocino. The older rule used inflow to Lake Pillsbury on the Eel River.
Starting May 1, 2027, in a Normal year, lower the minimum river flow. Upper Russian River, from the East and West Fork confluence to Dry Creek: from 185 to 125 cubic feet per second. Lower Russian River, from Dry Creek to the ocean: from 125 to 70.

The lower flows would last until the order ends or October 15, 2027, whichever comes first. No change to Dry Creek flows is proposed.

The petition also asks that flows be measured as a 5-day running average. Single readings could dip to 110 cubic feet per second on the upper river and 60 on the lower.

Sonoma Water gives two reasons. Changes at PG&E's Potter Valley Project have cut water sent from the Eel River. And the 2025 Russian River Biological Opinion calls for a Lake Mendocino storage-based index and lower Normal-year flows.

The same kind of change was approved for this year. A State Water Board order dated May 20, 2026 switched to the Lake Mendocino index and set the same lower flows, and it lasts 180 days.

What it means for you

This is about how much water must stay in the river and how Sonoma Water counts dry years.

The petition says Lake Mendocino held 66,886 acre-feet on August 24, 2026.

The documents we read say nothing about water bills or watering rules. If you want to know how this touches your tap, ask your water utility. See where Sonoma County tap water comes from and how the Russian River system works.

What happens next

The State Water Board has to decide whether to approve the petition. The documents we read do not show a decision.

If approved, the Lake Mendocino index would start November 16, 2026. The lower flows would start May 1, 2027.

The Sonoma Water Technical Advisory Committee next meets with the Water Advisory Committee on November 2, 2026. The October 5 agenda listed water supply conditions and the urgency change order as an item.

To read the petition, see Sonoma Water's public notices page. It lists a public notice dated September 17, 2026.

Where this came from

Sonoma Water's petition filed August 28, 2026, the State Water Board order dated May 20, 2026, Sonoma Water's public notices page, the October 5, 2026 Technical Advisory Committee agenda, and Sonoma Water's committee schedule page. This is a proposal by Sonoma Water. The State Water Board has not decided.

Sources

Checked 2026-10-12. Rules and programs change. If something here is out of date, the source above wins. Spot an error? See our corrections policy.