Mosquitoes in Pismo Beach tested positive for the West Nile virus.
The California Department of Public Health says the mosquitoes were collected on July 9th and 10th at the city's Chumash Park.
The creeks and freshwater ponds were treated with an insecticide on July 18. The best breeding conditions for mosquitoes is during warm weather.
Protect yourself by removing standing water in and around your home or business.
In California this year, there have been four confirmed human cases of West Nile virus. Two were in Los Angeles County.