Temporary Closure of Coyote Hills


The Alameda County Mosquito Abatement District will be conducting a helicopter treatment for larval mosquitoes which will require the closure of park trails. All park trails will be closed on Thursday, March 26, until operations are completed. Trails will potentially reopen in the afternoon.

WHY: Unseasonably high temperatures have created large numbers of marsh mosquitoes, primarily Culiseta inornata (the winter marsh mosquito) and Culex tarsalis (the encephalitis mosquito). Culex tarsalis is a possible carrier of West Nile virus. Access throughout the marsh is very difficult, making aerial application necessary.

TREATMENT PRODUCTS: Larval mosquitoes (those that are still in the water) will be treated with two bacterial products: Bacillus sphaericus (Bs) and Bacillus thuringiensis israelensis (Bti). Both Bs and Bti are extremely mosquito specific and do not affect other aquatic life. Products will be applied in granular form.

For more information, please go to the Alameda County Mosquito Abatement website,

The East Bay Regional Park District is a system of beautiful public parks and trails in Alameda and Contra Costa counties east of San Francisco Bay, established in 1934. The system comprises 119,000 acres in 65 parks including over 1,250 miles of trails for hiking, biking, horseback riding and nature learning.

Carolyn Jones
(510) 544-2217