Bollay

*106 Opinion

The property line between publicly owned tidelands and contiguous upland property is known as the mean high tide line. That line is not constant; it changes over time with the level of the sea and the erosion or buildup of the shore.

This case is a challenge to a policy of the State Lands Commission (Lands Commission) prohibiting development seaward of the most landward historical position of the mean high tide line. The challenge is limited to the argument that the Lands Commission’s policy is a regulation and, therefore, is not valid because it is an underground regulation—that is, it was not promulgated pursuant to the Administrative Procedure Act (APA; Gov. Code, § 11340 et seq.). While the Lands Commission effectively concedes that the policy is a regulation, it claims, and the Office of Administrative Law and trial court both held, that the policy is exempt from promulgation under the APA because it is “the only legally tenable interpretation of a provision of law.” (Gov. Code, § 11340.9, subd. (f).) The Lands Commission argues that its policy is required because of its legal duty to protect the state’s tidelands.

Contrary to the holdings of the Office of…