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Understanding Mudflow and the NFIP

The National Flood Insurance Program (NFIP) aims to educate the public about mudflow, including what it is, when it can occur and whether it’s covered by a flood insurance policy.

Defining Mudflow

Mudflow falls under the definition of a flood in the NFIP’s Standard Flood Insurance Policy (SFIP). The SFIP defines a flood as:

  1. “A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (one of which is your property) from:
    1. Overflow of inland or tidal waters;
    2. Unusual and rapid accumulation or runoff of surface waters from any source;
    3. Mudflow.*
  2. Collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above.”

*Mudflow is defined as, “A river of liquid and flowing mud on the surface of normally dry land areas, as when earth is carried by a current of water. Other earth movements, such as landslide, slope failure, or a saturated soil mass moving by liquidity down a slope, are not mudflows.”

Mudflow Conditions

Mudflows can develop in areas where upland or upstream environment features exist and water containing mud can flow down slopes and through channels. They are likely in the wake of wildfires that destroy the vegetation needed to support and strengthen hillsides or, more often, after periods of prolonged drought.

In both instances, the soil is loose and unable to absorb water. Heavy precipitation (such as rainfall or snowmelt) that might not be a problem under normal conditions can trigger fast-moving water that picks up earth, rock and other debris. These mudflows often happen with little-to-no warning and can travel several miles from their source, leaving nearby communities and rural homesteads vulnerable to devastation.

Are Mudflows Covered by NFIP Policies?

Yes, the NFIP can protect policyholders from the financial hardships mudflows can bring. As mudflow is a type of flood event the SFIP insures against, policyholders can start a claim to repair or replace covered property damaged by mudflow.

Immediately following a flood loss, you should contact your insurance agent or company. For a list of actions to take when starting a claim after a flood, review the NFIP Claims Handbook. As with every flood claim, an NFIP-registered adjuster will visit the property and help the policyholder document the claim, including whether or not the loss event meets an SFIP-defined flood.

The SFIP does not insure earth movement, even if the earth movement is caused by flood. A landslide—a slope failure event where rocks, earth or other materials move down a slope—is an example of earth movement that the SFIP does not cover.

The SFIP offers two types of flood insurance coverage: building and contents. Consumers are encouraged to purchase both types of coverage in advance of a flood event to protect the lives they’ve built. It’s important to secure flood insurance coverage well before it is needed as there is generally a 30-day waiting period before NFIP flood insurance policies become effective.

For additional questions on the NFIP and starting a claim, connect with an insurance agent or review your policy. In addition, you may visit or contact FEMA Mapping and Insurance eXchange (FMIX) at 877-336-2627.

Related Resources

This publication was developed with information from the United States Geological Survey (USGS) and the Centers for Disease Control and Prevention (CDC).