At Big Lagoon beach, a short drive from Arcata, signs posted near the parking lot warned beachgoers not to turn their back to the surf and to pay special attention to sneaker waves.
A steep slope of beach leads to the water's edge, where waves break with a boom right on shore. Officials warn beachgoers not to turn their backs to the water.
On Saturday, as the family walked along the beach, Howard Kuljian threw the stick and the dog gave chase, said Dana Jones, a state parks district superintendent.
Seeing his son in the water, Kuljian leapt to action, and disappeared into the frigid water.
Gregory managed to pull himself back onto the sand, but after realizing his father was drowning, both he and his mother went in to save him.
A nearby bystander called police. By the time help arrived, it was too late.
Jones said the officer wasn't able to get to the family members because of the high surf.