Neglected or Green Pools

Neglected or “green” swimming pools pose a serious health threat to the residents of San Diego County.  Mosquitoes that can carry West Nile virus and other diseases harmful to humans use green backyard pools to breed in as little as one-quarter inch of standing water and multiply into the millions. 

The County of San Diego Vector Control Program utilizes an aerial surveillance program to locate, identify, and treat green pools that could otherwise go unnoticed indefinitely.  

Report Green Swimming Pools

Contact the Vector Control Program if you notice a green swimming pool in your neighborhood or know of a foreclosed or unattended home that has a swimming pool.  Vector Control Technicians will treat the pool to prevent it from breeding mosquitoes (treatment will not affect the appearance of the pool but will reduce mosquito numbers). When reporting a green pool, please include your name, phone number, and the address where the pool is located. 


Properly maintaining your pool helps prevent mosquito breeding, keeping you and your neighbors safe and healthy. A regularly cleaned pool with a working filtration system helps ensure mosquitoes cannot breed. Pool maintenance may include:

pool under construction
  • Maintain Filtration System: Ensure pool's filtration system is working properly by routinely checking parts such as the pump, filter, return inlets, and main drain
  • Use Sanitizer: Pool sanitizers kill bacteria and inhibit the growth of algae and other organic contaminants in your pool. The most common pool sanitizer is chlorine. 
  • Regular Cleaning: Skim the leaves and other floating debris from the water
  • Remove Standing Water: Drained pools, pools under construction, and pool covers can collect standing water from rain and irrigation. Drain pools and dispose of liquid pool waste in a way that keeps our waterways clean. 


Mosquito Fish

Mosquitofish can be used in green pools to control mosquito larvae. The fish eat the young mosquitoes that live in the water.  The County of San Diego offers free mosquito fish at several distribution locations throughout the area.


Larvicides can be used to control mosquitoes in green pools, especially when there is only a small amount of standing water. Bacterial larvicides kill mosquito larvae but are harmless to people, plants, pets, and wildlife. They can be purchased online or at home improvement stores in dunks, granules, or liquid form. 


  (858) 694-2888