News Release

For Immediate Release — Friday, September 15, 2023

Contact: Nola Woods, Public Affairs Director

Direct: 925-771-6158

Cell: 925-250-6502



Report Neglected Swimming Pools to Reduce Risk of Mosquito-borne Disease

CONCORD, CALIFORNIA - The Contra Costa Mosquito and Vector Control District (District) reports four more groups of trapped mosquitoes and four more dead birds have tested positive for West Nile virus (WNV) in Contra Costa County. The dead birds were collected from Kensington, Danville, and Concord (2); while the mosquitoes were trapped in Discovery Bay, Martinez, Concord, and Brentwood. So far this year, there have been 41 dead birds, 16 groups of trapped mosquitoes, and five sentinel chickens that have tested positive for WNV.

Unmaintained swimming pools increase the risk of mosquitoes and WNV because they provide a place where thousands of mosquitoes can develop from eggs to biting adults.

West Nile Virus activity in Contra Costa County as of September 15, 2023.

Red markers are WNV+ Mosquito locations — Blue markers are WNV+ Dead Bird locations —

Green markers are WNV + sentinel Chicken locations

"Neglected (unmaintained or improperly maintained) swimming pools in residential neighborhoods have the potential to produce thousands of mosquitoes that are capable of becoming infected with WNV, putting the entire neighborhood at risk. That is why it's so important to maintain swimming pools properly and to report neglected swimming pools to the District to reduce the risk of mosquitoes and WNV," said Scientific Program Manager Steve Schutz, Ph.D.

Contra Costa County residents can report an unmaintained swimming pool by phone at 925-685-9301 or online. Neglected swimming pools may be reported anonymously.

In addition to reporting unmaintained swimming pools to reduce the risk of WNV, the District also advises Contra Costa County residents to:

  • Use an EPA-registered insect repellent that includes one of the four most effective active ingredients: DEET, Picaridin, IR3535, or the repellent version of Oil of Lemon Eucalyptus
  • Make sure door and window screens are in good working condition
  • Report dead birds to the California West Nile Virus Dead Bird Call Center
  • Contact the District to request mosquito service

Contra Costa County residents can report dead birds by phone at (877) WNV-BIRD (968-2473) or online. County residents can also request mosquito service for their residential properties by calling (925) 685-9301 or online.

Since 2003, 77 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. For human case information, please visit the California Department of Public Health Vector-Borne Disease Section online.


Contra Costa Mosquito & Vector Control District, an independent special district and public health agency, is located at 155 Mason Circle in Concord.

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