Flood water into groundwater without a permit: what the state says ahead of El Niño storms

By The Downspout · Posted Oct 26, 2026 · 4 min read

California lets people divert flood water to refill groundwater without a water right permit, but only after a local or regional agency issues a flood notice. The State Water Board scheduled a public online workshop on the rule for October 26, 2026, ahead of a possibly strong El Niño winter.

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What this rule is and who it covers

A water right is legal permission to take water from a creek or river. To divert water means to take it out of a creek or river.

A section of the state Water Code, section 1242.1, makes an exception for floods. During qualifying floods, you can divert flood water to recharge groundwater without a water right permit. Qualifying means a local or regional agency has said flooding is imminent. Recharge means putting water underground so it refills an aquifer, the layer of soil and rock that holds well water.

It is a state rule, so it covers Sonoma County too. The State Water Resources Control Board, called the State Water Board below, runs water rights in California. It says the rule helps put water underground while helping to reduce flood risks.

What it means for you

If you own land by a creek and want to recharge, do not divert anything until your local or regional agency issues a flood notice. Ask that agency now how it tells the public about flood risk.
If you plan to divert, identify your diversion and recharge sites before the storm. Be ready to file three reports on time (listed below).
If you have questions about the rule, the State Water Board lists FloodDiversion@waterboards.ca.gov for questions on Water Code section 1242.1. A water rights attorney can also advise you.
For smaller projects at home, see our guide to recharging groundwater at home and our El Niño page.

Our view: refilling aquifers in wet winters fits our leaning toward conservation. The rule also has limits. The state's flyer says you cannot choose when diverting starts, you gain no water right from it, and you must report every time.

What happened

The State Water Board's Division of Water Rights scheduled two online workshops on groundwater recharge. October 19 was on getting ready to recharge with a temporary permit. Monday, October 26, 2026, 10 to 11 a.m., is titled “Capturing Floodflows Without a Permit.” That one is about this rule. The board says recordings will be posted on its website shortly after each workshop.

The board's reason: developing El Niño conditions are raising the chance of above-normal rain this winter. El Niño is a warming of the eastern Pacific Ocean that often brings more storms to California. The board says the chance to recharge may come quickly, but permitting may not.

Sonoma County is preparing too. On October 6, 2026, the Board of Supervisors proclaimed an emergency over the developing El Niño. The county release says forecasters give a 75 percent chance El Niño could reach historic levels this winter.

The rules in the state's flyer

The flyer is titled “Prepare Now for a Super El Niño.”

You can divert only during qualifying flood conditions.
A local or regional agency decides when those exist. It must have a flood protection plan, or a flood-risk section in its latest general plan. A general plan is a city or county's long-range planning document.
That agency must first tell the public that downstream water is at imminent risk of flooding land, roads or structures. You may start only after that notice.
You do not decide when diverting starts or ends. Stop as soon as the agency's notice says flood conditions have lessened and downstream flood risk has ended.
Use existing recharge sites whenever possible, such as percolation ponds. A percolation pond is a basin that lets water soak into the ground.
If none is available, the water can go on land used for agriculture in the last three years. The land must not be associated with animal facilities. It must not be where manure or pesticides were recently applied.
There is no limit on the amount. You must use existing infrastructure or temporary pumps with protective screens. You must not create new flood risks, harm water quality or water supplies, or damage critical infrastructure.
The water does not become yours. The flyer says these diversions create no water right and give no ownership or control of the water.

The flyer says other conditions may apply, and extra conditions apply when diverting from tributaries of the Sacramento-San Joaquin Delta. It points to the State Water Board's Flood Recharge Diversions Technical Guidance Document for details.

You must also file three online reports with the State Water Board, and with your local groundwater agency if one exists. That agency is called a GSA, short for Groundwater Sustainability Agency.

Diversion Notice: at least 48 hours before diverting if possible, but no later than 48 hours after you start.
Preliminary Report: within 14 days after you start.
Final Report: within 15 days after you stop.

The flyer adds that a GSA can set up a program that gives groundwater credits for qualifying recharge.

What happens next

The workshop recordings are to be posted. The board's wet winter page lists permitting materials as “coming soon”: a permitting flyer, an application guide, two technical guides and a frequently asked questions page. Whether any local or regional agency in Sonoma County plans a recharge program this winter is not in these documents.

Where this came from

The State Water Board's workshop notice for October 19 and 26, 2026, its “Preparing for a Wet Winter” page, and its “Prepare Now for a Super El Niño” flyer. The Sonoma County facts come from the county Department of Emergency Management release of October 6, 2026. The El Niño definition comes from the Governor's office release of October 9, 2026.

Sources

Checked 2026-10-26. Rules and programs change. If something here is out of date, the source above wins. Spot an error? See our corrections policy.