Beach report: High fecal-coliform counts mean quiet times at East Vancouver's Trout Lake

The reason is immediately apparent to anyone who goes to the Vancouver Coastal Health Authority website and downloads beach-water-quality reports. There, you can read the fecal-coliform counts at nearly two dozen swimming spots in Vancouver, North Vancouver, West Vancouver, and Richmond. One location has consistently stood out with the highest number: Trout Lake. The most recent summary, issued on August 2, cited 354 bacterial counts in a 100-millilitre sample. That’s well over the ceiling of 200 parts per 100 millilitres.

The only location higher than that in the region was Rocky Point Park, a nonbathing beach in Port Moody, which posted 369 in the last report issued by Metro Vancouver. The next highest coliform count at a Vancouver bathing beach was 97 at Sunset, according to the health authority. Eagle Harbour in West Vancouver posted a count of 94. This means that Trout Lake was almost four times as polluted as any other bathing beach in the western part of the Lower Mainland. (For the 30-day period ending on July 19, counts reached 128 at English Bay and 124 at Sunset, according to Metro Vancouver.)

The supervisor of maintenance management for the Vancouver park board, Ian Harvey, told the Georgia Straight by phone that staff have been trying to solve the mystery of high coliform counts for a few years. He even asked two groups of fourth-year UBC engineering students to examine the issue. “The conclusion,” Harvey noted, “is that there is virtually no flow in the lake at all.”

The park board pumps water into the south end of the lake, adding just over three metres to the height over summer. But according to Harvey, most of that drops to the bottom because the lake is on top of peat, so this doesn’t flush out pollutants. Meanwhile, there is an off-leash dog park at the north end of Trout Lake, which has been blamed by some area residents for the swimming ban.

Harvey, however, maintained that this isn’t the source of the problem. “Because there is no flow, really, whatever is happening on the north side has no impact on the south side,” he said. “The other thing about fecal coliform is it has the half-life of less than two days—which means if you have an independent, isolated poop in the water, two days later, it will be at half the level. Two days later, it will be half again. So basically, if you’re reading and continuing to read a ”˜hot’ lake, it’s because there is a reinforcing thing happening.”

Harvey revealed that the last set of readings by the Vancouver Coastal Health Authority disclosed a 10-to-one ratio between different areas of the lake. The east end posted 1,800 coliform counts per 100 millilitres, whereas the west side generated a count of 180. What could explain such a wide discrepancy? Harvey believes the primary source is birds.

“This year, we have physical evidence,” he explained. “I’ve got photos of bird seed on the beach. Someone this year has decided to feed the birds—and maybe they have been feeding them through the winter. Because the lake staffing is only there when the lifeguards are there, no one has noticed.”

There are two new, makeshift signs on the beach urging people to stop feeding the birds. With a certain irony, Harvey pointed out that there are virtually no birds on the north side because dogs scare them away to the other side of the lake. “The day I was there early on [this year], there were at least two pairs of Canada geese, which, of course, are fairly big fowl, but there were maybe a dozen or so ducks as well,” he said. “The public-education piece, which we’re going to have to work on, is explaining to people who feed the birds that what they’re doing is changing the water quality so that people can’t swim in the summer.”