California El Niño: Regulatory Guidance for Emergency Stream and Channel Work

• Prepare for a potentially historic storm season: A very strong El Niño could increase the potential for flooding, erosion and impacts to streams, channels and related infrastructure, although conditions will vary across California
• Use the time before storms to get ready: Identify vulnerable sites, establish monitoring and decision procedures, document baseline conditions and develop a plan for potential emergency work
• Know what to do when emergency work is needed: Document changing conditions and actions taken, coordinate with the appropriate regulatory agencies and understand how California’s emergency measures may affect regulatory pathways and response options

California is moving into this year’s winter season with clear signals to prepare early. The National Oceanic and Atmospheric Administration (NOAA) reports a greater than 90% chance of a very strong El Niño during the Northern Hemisphere fall and winter 2026–2027.

For public agencies responsible for streams, flood channels and related infrastructure, periods of heavy rain can create conditions that require rapid action, including flooding, erosion, debris flows and damage to infrastructure.

On September 21, Governor Gavin Newsom declared a state of emergency to mobilize state resources ahead of the super El Niño storm season. The action directs state environmental and natural resource agencies to assist local preparedness efforts through expedited permitting and other regulatory coordination.

Emergency conditions leave little time to establish documentation procedures and how to coordinate the regulatory response.

Before storms arrive, agencies can strengthen readiness through five practical steps:

These steps create a stronger foundation for planning, preparedness, response and recovery, helping teams recognize when conditions have materially changed and providing context for decisions made under emergency conditions.

Emergency stream and channel work can involve several regulatory agencies when it comes to water resources permitting and compliance. Depending on the location and work proposed, agencies may need to coordinate with the U.S. Army Corps of Engineers (USACE) for qualifying emergency repair and protection activities, the Regional Water Quality Control Board (RWQCB) for water-quality requirements and the California Department of Fish and Wildlife (CDFW) for work affecting streams and wildlife resources.

The specific process varies by agency and circumstance, but the core approach is consistent: communicate early, provide appropriate notification, minimize environmental impacts, document the work and complete required follow-up.

California’s September 21 state of emergency adds an important consideration. The proclamation directs state environmental and natural resource agencies to fast-track permitting and identify ways to support local flood, landslide and debris-flow preparedness.

That does not mean environmental requirements have broadly been waived. It does mean agencies have an opportunity to clarify potential regulatory pathways, contacts and responsibilities before an emergency requires immediate action.

If conditions require emergency work, documentation is key.

That record may include:

• Conditions that initiated the emergency response, e.g. a stream bank caved in or high flows
• Work footprint and site access
• Actions performed and relevant quantities
• Pre- and post-work photographs
• Measures used to avoid or minimize environmental impacts

Early regulatory coordination remains important. Notifications, authorizations and follow-up requirements differ among USACE, RWQCB and CDFW, making it valuable to know in advance who will manage those communications.

Emergency repairs may address the immediate threat without representing the site’s permanent condition. After the immediate response, agencies may need to evaluate additional recovery, such as ecological restoration and nature-based solutions that support longer-term site stability, ecosystem function and resilience.

Preparedness is straightforward: Know the vulnerable sites. Know the triggers. Know the regulatory pathway. Know who will coordinate the response.

Onterris brings together water resources expertise, environmental permitting know-how and strong regulatory relationships to help public agencies plan before conditions change and navigate regulatory coordination when emergency work becomes necessary.