In Citizens for Odor Abatement v. City of San Diego, published February 9, 2017, the Fourth District Court of Appeal, Division 1, affirmed summary judgment in the defendant city's favor in an action alleging that the noxious sea lion waste odors emanating from La Jolla Cove were a public nuisance. The city had attempted to eliminate the odor, but while it was successful in addressing the odor from bird droppings, it had not succeeded in eliminating the sea lion dropping stench. The plaintiff alleged that a city fence had encouraged sea lions to accumulate in a portion of the cove by keeping humans out of the area. In its motion, the city presented expert evidence that several factors other than the fence caused the sea lion population to grow, and that the fence, built decades before the population growth, did not cause the growth. In response, the plaintiff presented evidence, including an expert declaration, that the population growth occurred after the fence was built. The expert opined that the fence caused the sea lions to feel more comfortable resting on the fenced-off bluff. The trial court sustained the city's objection to the expert declaration as a classic post hoc, ergo propter hoc (it happened afterward, therefore it was caused by) logical fallacy, and as contradicted by the evidence.
The appellate court noted that a public nuisance cause of action requires that the nuisance be caused either by something the public entity did or something it had a duty to do but failed to do. The trial court correctly ruled that the undisputed evidence failed to establish this causal nexus. The city's expert evidence disproved the theory that the fence caused the population growth. The plaintiff did not appeal the ruling sustaining the objection to the plaintiff's expert's declaration, and the trial court correctly excluded it. The evidence from locals that there was not an odor problem before the fence did not create an issue of fact as to whether the fence created the odor problem; that was a post hoc, ergo propter hoc fallacy. The plaintiff also failed to show that the city failed to act to attempt to alleviate the odors, even assuming it had a duty to do so. The court also rejected a theory that the plaintiff was entitled to mandamus on the ground that the city had assumed an obligation to alleviate the odor. A memorandum issued by the mayor asserting that the city would attempt to eliminate bird waste odor did not impose a duty to alleviate sea lion waste odor.