Neglected or Green Pools

green pool

Neglected or “green” swimming pools pose a serious health threat to the residents of San Diego County. Mosquitoes use green backyard pools to breed and multiply into the millions. The County of San Diego Vector Control Program utilizes an aerial surveillance program to locate, identify and treat these green pools that could otherwise go unnoticed indefinitely. Neighbors are encouraged to report green swimming pools to the Vector Control Program so mosquito fish can be put into the pool to control mosquito breeding. These little fish produce live young and will eat the mosquito larvae as long as they are present.


Mosquitoes only need one half (1/2) inch of standing water to breed and turn into biting adults. Green pools are a threat to public health because mosquitoes can carry West Nile virus and other diseases that harm humans.


Report Green Swimming Pools

If you notice a green swimming pool in your neighborhood or know of a foreclosed or unattended home that has a swimming pool, please contact the Vector Control Program. Vector Control Technicians will treat the pool to prevent it from breeding mosquitoes.  


To report a green swimming pool, please call (858) 694-2888 or email

Please include your name, phone number and address you are reporting.

Filter your Pool

It is important to properly maintain your pool to help keep you and your neighbors safe.  A working filtration system will keep your pool healthy and clean. In order for the filtration system to be operating correctly, you need to make sure all the pieces are working properly.  You should routinely check:

    • The Pump: This is the heart of the filtration system.  It draws water from the main drain and skimmers and pushes it through the filter
    • The Filter:  This removes very small particles and debris from the water
    • Sanitizer: A sanitizer supplies bacteria killing chemicals to your pool
    • Return Inlets: Inlets return the filtered and chlorinated water back into the pool
    • Skimmers: These skim the leaves and other floating debris from the water
    • Main Drain: This is used to suction the water to the filtration system and to drain the pool

    If all of these parts are working properly you will have a clean pool where mosquitoes cannot breed.


    Mosquito Fish

    Other Solutions

    If you are not able to keep your pool treated, there are other actions you can take to stop mosquito breeding. The County of San Diego offers free mosquito fish at several distribution locations throughout the area, which feed on mosquito larvae. You can also purchase larvicide at home improvement stores.

    Draining your pool is only a temporary solution. Rain and irrigation water can build up and create more standing water. In addition, water trapped on the top of pool covers can also create a mosquito breeding ground.


    Pool Construction

    Mosquito breeding can occur during pool construction. In order for your pool to have a strong foundation it is important to spray the cement mixture. This, however, can lead to standing water. Water can collect at the bottom of the pool before it's chlorinated.

    Swimming Pool Under Construction Mosquitoes need only one inch of standing water to breed and can complete their life cycle in as little as one week.  Creating a place for mosquitoes to breed so close to residential areas is a danger to public health and safety.  Mosquitoes can carry the West Nile virus and other diseases, so it is important to take the following steps to prevent their breeding during pool construction:
    • Use products that control mosquito breeding in your pool such as Bti dunks, which kill mosquito larvae.
    • Make sure to use products that do not harm people, animals and plants.
    • Make sure to follow the directions on all labels carefully.


    After Construction

    Once your pool is filled with water, sanitized and filtered it is no longer a threat to public safety.  Make sure to keep your pool clean and your filter running to prevent mosquito breeding in your pool.


    For More Information On 
    WNV Or Other Vectors Contact: 
    (858) 694-2888
    SD Fight the Bite Homepage