California Code, Harbors and Navigation Code - HNC § 774.4

(a) This article does not impose any mandatory duties upon any public entity to monitor sea or weather conditions or to warn or prevent vessels from leaving or entering a harbor entrance during unsafe conditions.

(b) No public entity or employee thereof is liable for any injury which results from any act, or omission to act, prohibiting an operator for a for-hire vessel from leaving or entering a harbor.