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Are ‘green pools’ deadly?

Public health officials refocus attention on battle against West Nile

Posted: July 24, 2008 1:21 a.m.
Updated: September 24, 2008 5:03 a.m.
County officials are giving out free mosquitofish to be placed in small ponds. The fish could prove valuable in a the fight against West Nile disease. County officials are giving out free mosquitofish to be placed in small ponds. The fish could prove valuable in a the fight against West Nile disease.
County officials are giving out free mosquitofish to be placed in small ponds. The fish could prove valuable in a the fight against West Nile disease.

Green is good when it comes to environmentally friendly living in Santa Clarita Valley, but not when it comes to swimming pools abandoned in foreclosures.

Public health officials working diligently to stop the spread of West Nile Virus by mosquitoes breeding in stagnant water are turning their attention to this year’s main battleground — “green pools.”

With a record number of foreclosures registered in the Santa Clarita Valley comes a high percentage of neglected backyard swimming pools that turn quickly into breeding grounds for mosquitoes carrying the deadly West Nile virus.

Last week, county Supervisor Michael D. Antonovich issued a statement calling for “renewed action to prevent West Nile virus epidemic.”

In it, he said: “Los Angeles County is committed to preventing this virus from growing to epidemic proportions.”

His call for “renewed action” was prompted by the discovery of several dead birds found in the San Gabriel Valley that tested positive for the virus.

One dead crow found in Canyon Country in late April tested positive for the virus, a spokesman for the Los Angeles County Vector Control District said Wednesday.

Upon receiving news of the San Gabriel birds, Antonovich called for a “multi-agency coordination” to stop the spread.

Specifically, he directed the Department of Public Health and Public Works to investigate and clear open waterways that harbor mosquito breeding sites.

The West Nile virus is transmitted to humans and animals through mosquito bites and was first detected in the United States in 1999 in New York City.

The symptoms are flu-like and include fever, headache and body aches. There is no treatment for the virus. Fewer than 20 percent of those infected develop symptoms, and about 1 percent develop serious illness.

A public health spokeswoman said “green pools” are becoming this year’s hot new breeding site.

“What we’re seeing now is properties that have been vacated due to foreclosures and are not being maintained that turn into green pools which are excellent mosquito breeding spots,” said Dr. Rachel Civen, with the county Department of Public Health and Public Works.

“Some of our Vector Control people fly over areas with helicopters and if they see a green pool, they call the owner which turns then to the bank,” she explained.

Vector control officers do not need permission to enter a property suspected of having a “green pool” if there appears to be a compelling public health issue.

At least 550 homes in Santa Clarita Valley are in foreclosure, according to numbers tabulated Wednesday by

At least 145 of those homes are in the Canyon Country area where the diseased crow was found.

One of the environmentally friendly solutions used to address the “green pools” problem involves the Gambusia affinis, or as it’s called among vector control officials, the mosquitofish, which is native to southern and eastern portions of the United States.

Although it is not technically indigenous to the Santa Clara River watershed, the mosquitofish was introduced to the state 85 years ago.

Since then, public health officials have reported that the tiny fish is one of the most effective non-insecticidal and non-chemical methods of controlling mosquitoes.

Mosquitofish do not lay eggs, but rather give birth to live young and need no special environment to thrive.

Chemicals used to address mosquito stagnation, however, would not be a healthy environment for the mosquitofish.

“It has to be one or the other,” said Truc Dever, the county’s Director of Community Affairs.

As far as the county is concerned, mosquitofish are intended to be used for stocking ornamental ponds, “green pools” and animal water troughs.

One large ornamental pool regularly inspected by the county is the Bridgeport “Lake” on McBean Parkway at Newhall Ranch Road.

“We have guys go out there and inspect it every 10 to 15 days to make sure there is no stagnant water and no mosquito breeding,” Dever told The Signal on Wednesday.

Marlee Lauffer, spokeswoman for Newhall Land and Farming Co., the developer that built Bridgeport, said the “award-winning” lake at Bridgeport is “ecologically sensitive” with a bio-filtration system in place.

“It does have a circulation system,” she added.


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