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Quarterly Newsletter and Updates

Summer 2023

More water = more mosquitoes, right? Well…not exactly.

Due to the large amount of rain we had in winter, many residents (and even a few journalists) predicted large amounts of mosquitoes and high numbers of West Nile virus this summer. Though it is still early in the season to declare complete victory over mosquitoes, in some cases the rain has actually been beneficial for mosquito control, especially in creeks. Our years-long drought affected the amount of flowing water in Alameda County creeks, many of which had irregular and hard to reach puddles that held standing water for months. Mosquitoes require standing water to complete their life cycle, and small puddles in creek beds could produce mosquitoes if they were not found and treated before mosquitoes reached adulthood. With the large amount of rain we experienced this past winter, many of those small depressions in creeks were flushed out and have been filled with silt or now have fresh, streaming water. If the water is flowing consistently, the risk of producing mosquitoes is extremely low. While we cannot predict how long the creeks will have flowing water, residents are advised to connect with the district if they notice standing water in creeks in the upcoming months. 

What is the biggest issue? Forgotten items

District staff have noticed many of the mosquito concerns from residents are often due to standing water in neglected pools, forgotten backyard items such as toys or buckets, and ponds with overgrown algae. Look over the following list to see if you have these items around your home, and if any are holding water.

West Nile Virus (WNV) reminder 

Earlier this year the district found a WNV positive mosquito pool and two WNV positive crows recently in Pleasanton. West Nile is an endemic disease, meaning it is in our environment and occurs regularly, however Alameda County has had very few human cases within the past ten years. The best way to avoid West Nile virus is to avoid mosquito bites, by using preventative measures such as getting rid of standing water, and defensive measures like using mosquito repellent and wearing long, loose clothing. The public can help with WNV detection as well by calling in any dead birds that are found in the county.

Wild birds are the main source of WNV for mosquitoes. When certain birds become infected with WNV, they will have WNV in their blood. If a mosquito bites an infected bird and feeds on their blood, the mosquito can become infected and pass the virus on to people or other animals that they bite. Not all birds that are infected with WNV will get sick, but WNV can make some birds very sick and even cause death. Corvid birds (such as crows, jays, ravens, and magpies) are the most likely to get sick and die from WNV. Signs of WNV in birds may include uncoordinated movement, a lack of energy, and difficulty breathing. The Dead Bird hotline is 1-877-WNV-BIRD (1-877-968-2473) and you can also file a report on the website, https://westnile.ca.gov/report To learn more about West Nile virus and to see the latest numbers, you can find them on the California Department of Public Health’s website for West Nile virus. 

Social Media Moment

Yikes! We found not one but TWO mosquito egg rafts in one pot. Can you spot them? They look like little pieces of bark or dirt, but they each can contain 80-100 eggs. The best way to get rid of them is to get rid of the water. But if you can't do that, give us a call 510-783-7744


ACMAD participated in a study of pesticide abundance in storm water drains and catch basins. Upon reviewing the data the study concluded that "underground urban catch basins constitute an important secondary source for extended and widespread contamination of downstream surface waters by pesticides such as pyrethroids in urban regions."

Learn more at: Pyrethroid insecticides in urban catch basins: A potential secondary contamination source for urban aquatic systems

Events and outreach

We have been busy at different events and schools over the past six months. A few new events for us this year include:

* Bay Area Carnivorous Plant Society Showcase (Alameda)

* Halkin Elementary (San Leandro)

* East Bay Municipal Utility District 100th Anniversary Celebration (Oakland)

* Healthy Families Festival (Emeryville)

* Safe Kids festival (Oakland)

And more! If you have an event or outreach opportunity for our team, connect with Public Outreach Coordinator Judith Pierce at [email protected]

West Nile Virus Reminder

More WNV information

Alameda County Mosquito Abatement District


[email protected]


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