January 1, 2007

Vancouver residents unfazed by city's first-ever boil-water advisory

By: Mark Sabourin

Though BC residents are somewhat accustomed to seeing turbid water pouring from their faucets, the week-long boil-water advisory that affected residents of the Greater Vancouver area last November was an anomaly. If Mother Nature deals the lower mainland another blow like the one it dealt this fall, it could happen again, but come 2008, the region's problems will be behind it.

On November 16, public health officials issued a boil-water advisory affecting some two million residents of Vancouver and environs. The advisory was not fully lifted until 12 days later.

"Turbidity is an issue that affects Greater Vancouver's water supply during periods over very, very heavy rainfall," says Bill Morrell, corporate communications division manager for the Greater Vancouver Regional District (GVRD). It is neither an unusual problem, nor is it deeply troubling, he says, as it has little or no significant health impacts.

In fact, it's a province-wide issue, says Richard Taylor, executive director of the Union of British Columbia Municipalities. It's an issue that crops up often in smaller, unincorporated communities.

Most of the province's drinking water is drawn from protected watersheds. Contacted by E-mail, Duncan Ellison, executive director of the Canadian Water and Wastewater Association says, "The general presumption has been that protected watersheds are 'safe' and that all is needed is disinfection."

Though Vancouver got all the attention because of its boil-water advisory, that was an anomaly, says Taylor. If there's a problem, it lies in the smaller systems that are costly to upgrade.

That having been said, drinking water quality for the bulk of the population is high, if only because the population is concentrated in large municipal areas such as the GVRD and the Capital Region with large, well-managed protected reservoirs.

But turbidity is not entirely benign, as it can have an impact on disinfection, and Morrell admits there is a statistical correlation between turbidity and gastroenteritis. That's why the GVRD is nearing completion of a $600 million filtration plant, scheduled to come on stream at the end of 2008, "that will make these kinds of events a thing of the past," says Morrell. Until then, the region will continue to be served by treated but unfiltered drinking water from three reservoirs: Capilano, Seymour and Coquitlam.

In consultation with public health authorities, the GVRD has adopted a policy of increasing disinfection when turbidity reaches 1 NTU (nephlometric turbidity unit, which measures the opacity of the water). A public notice goes out at 5 NTU, mainly for the benefit of persons with compromised immune systems. Morrell says this happens once or twice a year.

But last November's record rainfall caused unusual runoff into the region's reservoirs. "We were seeing numbers in the Capilano and Seymour reservoirs approaching 70 NTU," says Morrell, "and in the streams that feed the reservoirs, numbers like 300 NTU, which is like chocolate milk.

"This is the first boil-water advisory that's ever been issued in Greater Vancouver," Morrell notes. But "at no time was the microbiological quality of the water a problem." The water was unattractive, but not necessarily unhealthy.

The boil-water advisory was issued by public health authorities "in an abundance of caution."

Citizens seemed to take it in stride. Morrell says he was the point of contact for media and for much of the public. The number of public complaints (as opposed to inquiries) was negligible.

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