NEWS: Science to lift fog on buffer zones

August 20, 2010
Winnipeg Free Press

Malathion drift will show their ideal width

The city and province have agreed to stop playing politics with mosquito-control policy by conducting scientific trials to determine the proper size of pesticide-free buffer zones.

The City of Winnipeg's insect control branch is preparing to study the way malathion drifts in the air under a variety of wind and temperature conditions in an effort to figure out how large buffer zones must be to make sure properties inside the zone won't be sprayed with the pesticide during nuisance-mosquito fogging operations.
"We need to be able to go out and say without any reasonable doubt, 'Is that property going to be affected or not?' " city entomologist Taz Stuart said Thursday. "The best way to do that is to do a scientific study in a variety of conditions and see how they affect dispersion rates."

The scientific trials will effectively end a game of political hot potato that began in July, when the city asked Manitoba Conservation to determine the size of buffer zones.

Those zones were set at 100 metres almost three decades ago, before the use of global positioning satellite technology became widespread. The insect control branch now uses GPS technology to reduce buffer zones to 15 metres on either side of a registered property to be "reasonably certain" it won't be affected by malathion, Stuart said in a letter to Manitoba Conservation environmental licensing director Tracey Braun in late July.

But that 15-metre figure -- equal to the width of a residential lot in an older city neighbourhood -- was just the city's minimum suggested buffer-zone size. In a series of letters during the following weeks, Stuart and Braun determined the city should conduct scientific trials to be 100 per cent certain of the proper buffer-zone size.

In order to conduct the trials, the city must devise a research plan, select the location for the field testing and ensure it does not include any existing buffer zones, Braun said in a letter to Stuart this week.

The city must also apply for a temporary licence to disperse malathion when there is no need to fog for mosquitoes. Affected residents will be notified.

If the weather stays warm into September, it's possible the trials could be conducted this year, Stuart said. But it's more likely they will take place in 2011.

Factor in data-analysis time and buffer zones may not be reduced in size until 2012. St. Vital Coun. Gord Steeves, one of council's most vocal opponents of 100-metre buffer zones, said such a delay would be frustrating, but also necessary.

"As politicians, we don't have the expertise to simply mandate the smaller buffer zones. We are going to need the backup of science," Steeves said in a telephone interview from Orlando, Fla.

But Steeves also surmised it should be possible to make an interim reduction of the buffer-zone size, adding the decision to make buffer zones 100 metres is out of date.

"Ultimately, science can be as inexact as politics. At some stage, somebody is going to have to make a decision as to what makes sense."

Pesticide opponents hailed the decision to conduct scientific trials as a victory.

"We said, right from the start, we need to do more research to determine the best and most effective mosquito policy. To find that out, you can't do that on the back of an envelope," said Josh Brandon, of non-profit environmental organization Resource Conservation Manitoba.

"It sounds like Taz Stuart and the city's administration were under a lot of pressure from the politicians to get rid of the buffer zones as much as possible. But they didn't have the evidence to show that's safe."

In the same correspondence, Manitoba Conservation agreed to allow the city to reduce the public-notification time before fogging commences to 24 hours from 48 hours.

But the province has asked the city to provide more evidence to back up its request to reduce the number of days when city-wide trap counts are above 25 mosquitoes to two days from three.

bartley.kives@freepress.mb.ca


Skeeter-control update

In July, city council asked the Manitoba government to approve a number of changes to the city's mosquito-control policy. Here's an update on some of the requests:

Buffer zones: The city must conduct scientific trials to determine the size of buffer zones. The dispersal rate of malathion will be tested under various wind conditions and temperatures. The zones could wind up being as small as 15 metres on either side of a registered property, city entomologist Taz Stuart hypothesized. But the trials will determine the result.

Notification times: The province agreed to allow the city to reduce the public-notification period before fogging commences to 24 hours from 48 hours.

Preconditions for fogging: Currently, city-wide trap counts must average 25 mosquitoes or higher for three days. The province wants the city to provide more evidence to back up its desire to reduce the number of days to two.

 

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