Driving into floodwater in Arizona, and what the law says

Arizona’s flood law is one of the few statutes in the country with a nickname everybody knows. The Stupid Motorist Law is quoted in every monsoon news story, usually to explain why a driver will be billed for their own rescue after going around a barricade. Most of what circulates about it is roughly right in spirit and wrong in detail, and the details are the part that matters.

Two things are worth separating from the start, because they get mixed together constantly. The first is what water does to a vehicle, which three agencies publish figures for. The second is what the law does, which is a narrower question than people assume and is answered by a single section of the Arizona Revised Statutes.

This page is not legal advice. It is a reading of a public statute and of published agency guidance, and anyone facing a real question about liability needs a lawyer rather than an article.

What the water does

The published figures do not agree, and this site prints all of them rather than picking one.

Read as a range rather than as a disagreement, the three statements are closer together than the headlines suggest. Twelve inches is the floor: the National Weather Service’s national campaign says that is enough to carry away most cars, and it is the lower bound of the Phoenix office’s own one-to-two-feet figure. Two feet is the ceiling, and all three name it: the national campaign for SUVs and trucks, the Phoenix office for “most vehicles”, and the county for your car.

The number to plan by is the lowest one, twelve inches. If you plan by that, you are covered by all three agencies rather than by the agreement between them.

The single most useful line on the subject is the campaign’s own, which is not a depth at all: “It is NEVER safe to drive or walk into flood waters.” The depths are published so that a driver understands why not, not so that a driver can find the safe one. There is no safe one.

Myth: it is a crime to drive into floodwater

This is the most common misreading. A.R.S. § 28-910 creates no offence of its own, and it is not a criminal statute.

What it is, is a liability provision. Its own title is “Liability for emergency responses in flood areas; definitions”. Subsection A attaches liability for the cost of an emergency response to a driver who operates a vehicle on a public street or highway that is temporarily under water and barricaded because of flooding. Subsection B attaches the same kind of liability to somebody convicted of an offence under § 28-693, which is reckless driving.

In both cases the liability follows something else. In the first, the fact is the barricade and the flooded road. In the second, the fact is a conviction that already exists. Nothing in the section makes crossing water a charge in itself.

Myth: the bill is for the whole rescue

The statute caps the liability in its own words: the expenses of an emergency response “shall not exceed two thousand dollars for a single incident”. The cap is real, and it is the number every news story gets right.

What people miss is the sentence beside it. The same subsection says the liability is “in addition to and not in limitation of any other liability”, which is a plain statement that the $2,000 is a floor on the exposure rather than a ceiling on it. It limits the rescue bill. It says nothing about the value of the vehicle, an injury, or what an insurer decides to do.

Myth: the cap makes the whole thing survivable

Subsection D is the one people have never heard of, and it is the one with teeth. It expressly allows an insurance policy to exclude coverage for this liability.

That means the $2,000 rescue bill may not be covered at all, and that the larger costs of the incident sit on the ordinary footing of whatever policy the driver happens to hold. The cap is a mercy written into the statute; it is not a warranty about the consequences.

Myth: the law only applies behind a barricade

Half true, and the half that is false is the half that matters.

Subsection A does turn on the barricade. That is the fact the provision is built around: a flooded public street that has been barricaded is one where somebody with better information than the driver has already made the decision. Maricopa County’s instruction on the subject is in capitals (never drive around barricades) and it is written as an instruction rather than a warning.

But subsection B reaches a driver through a reckless-driving conviction under § 28-693, and reckless driving needs no barricade. Driving into water on a road nobody has marked yet can still be a reckless-driving charge, and the liability attaches to the conviction rather than to the signage.

So the honest reading is the blunt one. The barricade is a message; the water is the hazard. Nothing in § 28-910 gives anybody permission to cross an unbarricaded road, and the guidance from all three agencies is written against doing it.

What the statute says, in one table

What to do instead

There is no depth at which the guidance endorses driving through water on a road, and there is no situation in which the choice is between crossing and nothing. The National Weather Service attributes to the CDC the finding that over half of all flood-related drownings happen when a vehicle is driven into hazardous flood water, with the next largest share from people walking into or near it.

The Wash-Crossing Decision Flow works through the situation in the order it actually unfolds: where you are, whether there is a barricade, what the water looks like, and whether there is another way round. Most of the branches end in the same place, and the point of the tool is to get somebody there before they have talked themselves out of it. The flash-flood warning guide covers what the warnings mean, and the Monsoon Prep Checklist is where the seasonal preparation belongs, including the thirty-day flood-insurance wait that makes a policy bought during a storm useless for that storm.

A final note on scope. This page describes a statute and repeats agency guidance. It does not advise anybody on their own situation, and it cannot: whether a particular driver is liable under § 28-910, or what an insurer will do about it, are questions for a lawyer and an insurance policy rather than for a reference page about the desert climate.