|Overcoming Hills in the Valley|
Russ Parman may be just as pleased as the real estate community to see the housing market rebounding. That's because as manager of Santa Clara County Vector Control District in San Francisco's Silicon Valley, his team has logged more than 4,000 abandoned or "green" swimming pools over the past five years. The district has uncovered the extensiveness of the problem with the help of a very sophisticated aerial surveillance system that allows it to cover 100 square miles in a typical survey, performed up to four times a year. Prior to this efficient aerial approach, the district would discover only about 40 neglected pools per year due to residential privacy laws.
Now, Parman says, the number of neglected pools, which are a very significant source of mosquitoes in the Valley, seems to be tapering off as the market picks up and foreclosures are being sold. Even as it hopes to see a decline in green pools, the district will continue to conduct aerial surveillance. As abandoned pools are discovered, the district works closely with local residents and realtors to gain access to the homes to treat for mosquitoes. Parman says for six out of ten green pools the team identifies, they can plant mosquitofish and achieve season-long control. In instances where the presence of chloramines prevents this, they use FourStar® briquettes that provide extended release of Bti and Bacillus sphaericus combined, or Altosid® extended release methoprene briquettes. For heavy infestations of pupae or larvae, Agnique® monomolecular surface film is applied.
But green pools aren't the only challenge Santa Clara County Vector Control District faces. It also deals with unique adulticiding obstacles because of the considerable concerns regarding the use of pesticides in the Bay Area. The district fogs only after it has identified positive West Nile virus mosquito samples, and Parman explains that Santa Clara County is committed to community awareness as "one of the few districts that hand delivers informational flyers to every resident in a fogging zone." Originally, the district held community meetings before each fogging operation; now, this has evolved into a phone bank approach in conjunction with the flyers, which has significantly shortened the length of time from the discovery of positive mosquitoes to fogging operations, down to a three-to-four-day window.
Parman says, "This approach has worked well for us. We are confident in our surveillance and treatment combination." The surveillance Parman refers to is an intensive program that plants 40 EVS traps in a mile radius around each dead bird. The typical fogging treatment zone is three square miles, which usually equates to 7,000-10,000 hand-delivered flyers for each initial fogging treatment within the neighborhood. Another very effective public education tool is the use of "pictorials" that Parman offers to residents who call him with concerns. Believing many of his residents are suffering from misinformation about the risks associated with ULV fogging, he helps them understand the risk assessment by visually describing "how low ultra low really is", using examples such as:
"Imagine 1/4 inch of liquid in your kitchen measuring cup, and then stretching that out over an acre of ground (about 200x200 feet). That's one fluid ounce per acre. If we could do that, the resulting ‘film’ would be 10-40 times thinner than the wall of a soap bubble."
According to Parman, this usually does the trick. "Most people understand the miniscule degree of risk after this, even if they remain philosophically opposed to the use of pesticides." Even with this success, it's clear that public perception still weighs heavily on decision making in the district. Parman explains what has historically been the criteria for selecting its ULV fogging products: when it initially selected Pyranone® 25-5 years ago, "one of the reasons was the label said 'public health pesticide'... which served to reinforce the motivation for fogging operations." Eventually, the district switched to Zenivex® because of its low-risk classification, lower acute toxicity and absence of PBO. "Fortunately," says Parman, "we've also had good results with it."
Santa Clara County Vector Control District provides mosquito and vector control to more than 1.8 million people in Silicon Valley, but they've certainly had to overcome some hills in order to do so.