In 2006, technicians spent about 1 percent of their time responding to abandoned pools with pesticides to prevent mosquito reproduction but in 2007, a spokeswoman said it was more than 50 percent.
Mosquito reproduction is worrisome because they are the prime carriers of West Nile Virus, a potentially deadly virus that killed twenty people in California last year, according to the California Department of Public Health.
"Mosquitoes can reproduce hundreds of thousands of times in one pool," said mosquito vector spokeswoman Deborah Bass. "And they can fly at about a 5-mile radius."
The organization hired three extra technicians this year to focus specifically on pools and Bass said it was absolutely necessary. She said the district has a list with about 50 to 75 percent of the same pools from last year, as well as new ones from this year.
The West Nile Virus season varies according to weather and could happen as early as May, Bass said.
The best type of prevention comes down to the individuals, she said.
"We're calling upon realtors and residents to help us protect our communities," she said.
People can report abandoned pools to the Contra Costa County Mosquito and Vector District at (952) 685-9301.