Investigators are looking at bacteria that is naturally growing in a Stanislaus County lake.
The bacteria is believed to have nearly killed a Stockton man after returning from a camping trip.
Luis Lopez began feeling sick on June 7, the day after his family spent a camping trip at Woodward Lake.
Lopez had to be taken to the emergency room because he began feeling dizzy with a fever of 107. He spent six days in the hospital, losing 28 pounds.
Doctors discovered the bacteria inside the lake's water called campylobacter was the cause of Lopez's illness.
Two other family members also began feeling sick but not to the extent Lopez had suffered. They are all taking antibiotics.
The area around Woodward Lake does have signs posted -- warning of unusually high bacteria -- however there are no swimming restrictions.
The director of the county's environmental resources says an investigation will happen when they get a report from the California Department of Public Health.