How safe is your lake?
Grady Semmens
The Calgary Herald
August 8, 2004
Swimming, windsurfing, boating and
fishing are all pastimes commonplace at lakes such as
Arbour, Chaparral, Bonaventure and Bonavista.
But are these lakes safe for these
activities?
The simple answer is "yes,"
according to water quality experts and independent tests
conducted by the Herald.
However, the challenges in maintaining
these manmade bodies of water, as well as declining
standards for Calgary's recreational lakes, is raising
concerns the condition of the city's beloved swimming
holes could begin to sink.
A Calgary Herald investigation into the
water quality of Calgary's swimming lakes has revealed
that all of the city's community-owned lakes and the
public swimming areas of Sikome Lake and Chestermere Lake
are well within the Calgary Health Region's safety limit
for fecal coliform -- the only form of pollution regularly
monitored by local health inspectors.
Fecal coliform bacteria is an indicator
of contamination from the feces of humans and other
warm-blooded animals.
Water samples from the lakes collected
by the Herald and analyzed by Calgary's independent WSH
Laboratories Ltd. also found that all eight lakes met
federal and provincial guidelines for recreational human
contact, with the exception of Lake Bonavista where the
water's pH slightly exceeded the recommended maximum of
nine.
A measurement of acidity/alkalinity, pH
is rated on a scale of zero to 14, with seven being the
neutral pH of pure water. Calgary water is often slightly
alkaline, with a pH of about 7.9 in summer.
Eye and skin irritation can be caused by
exposure to water exceeding recommended pH values between
five and nine.
While several Calgary lakes have been
closed in the past due to excessive fecal coliform levels,
Calgary Health Region director of environmental health
John Pelton said they are generally considered to be clean
and safe for swimming.
"They're monitored so carefully and
they have good management staff," Pelton said.
"We've had to close some in the
past but it really doesn't happen that often," he
said, referring to temporary closures of Sikome Lake in
1991 and 1999 due to excessive contamination from bird
droppings. McKenzie Lake was also closed briefly in 1990
when fecal coliform levels skyrocketed after a septic tank
containing raw human sewage was illegally dumped in the
lake.
All of Calgary's swimming lakes are
tested weekly for fecal coliform bacteria. Staff at the
lakes are required to collect water samples from all
beaches and take them to the Provincial Lab of Alberta at
the Foothills Hospital, where fecal coliform levels are
measured and forwarded to the CHR for review.
If bacteria levels are found to be
higher than the maximum acceptable level under Alberta's
Public Health Act, Pelton said the lake is ordered closed
to swimming immediately.
"When I say immediately, I mean the
moment we get the bad result, it's closed within
minutes," Pelton said.
While all lakes rated far below the
maximum acceptable level of 400 colony-forming units (CFU)
of fecal coliform, the Herald's tests of Midnapore Lake
and Lake Chaparral found fecal coliform levels that would
trigger the suspicions of health inspectors. The Midnapore
sample contained 87 CFU while Lake Chaparral contained 61
CFU.
"Those are higher-than-normal
readings that would trigger us to ask for an immediate
resampling," Pelton said.
"If there is no change and it
didn't go down, it would warrant a very careful inspection
and sampling around the area to determine the cause."
Pelton said CHR records indicate fecal
coliform levels in all Calgary lakes have been around 10
CFU all summer, with a few "spikes" of 20 to 30
CFU, mainly due to weather conditions.
"When you have a gush of rain it
draws surface contamination around the lake into the lake
so we expect to see blips like that after
rainstorms," he said.
"Sometimes we'll see spikes that we
feel are deserving of a call. The inspector will call the
lake manager and tell him to take another sample from the
exact same spot immediately and then we follow that
through. If we get two spikes in a row then we start to
get more concerned."
Managers of Chaparral and Midnapore
agreed, saying the Herald's findings are unusually high
for their lakes and could be the result of storm run-off
or improper collection of samples.
"We take samples at three different
spots around the lake and ours have always come in at
under 10," said Patti Coburn, director of Genstar
Development Corp.'s Lake Chaparral.
"We have really good water quality
and it's improving as our community matures."
The Herald's samples were taken from the
beach areas of both Midnapore and Chaparral on July 20
when the weather was sunny and people were swimming in the
lakes. A rain storm had passed through the city the
previous afternoon.
Both lakes have had problems with geese
and gulls flocking to their shores in summer, leading to
higher fecal coliform counts. Coburn said birds are
becoming less attracted to Lake Chaparral as homes
gradually fill up the remaining lake-front lots.
Midnapore Lake manager Don Hoar said
weekly tests on his lake have been below 10 most of the
summer and that the highest fecal coliform count this year
was 40.
Hoar said several families of Canada
geese have nested on the lake's rocky southern shoreline
in the last few years and he is investigating measures to
keep them away.
"They started coming here a few
years ago and now they're coming back every year,"
Hoar said.
"I try to keep the beach as clean
as I can. We clean up bird droppings as often as possible
and we don't just brush them into the lake," he said.
"We're looking at what we can do to
get them to leave but it's tough because there's not a lot
we can do."
The community lakes that registered the
lowest overall bacteria readings -- McKenzie Lake and
Coral Springs Lake -- are both equipped with underwater
aeration systems that help reduce bacteria growth by
adding oxygen directly to the water. Other community lakes
use fountains and waterfall structures to circulate and
aerate water.
Unlike private community lakes that are
open only to members, Calgary's public swimming lakes
fared well in the tests but are drastically different when
it comes to the source and management of their waters.
Despite its huge number of users and
past closures due to waterfowl fouling the water, Fish
Creek Provincial Park's Sikome Lake had the second-lowest
level of fecal coliform and the lowest level of total
coliform bacteria.
That came as no surprise to park
officials who say a $1.8-million upgrade in 1989, which
included the installation of a water treatment plant to
chlorinate the lake's water supply, has been a success.
"It's not a surprise because we
treat our water, so it should do better than other
lakes," park planner Wayne Miekele said.
"When it leaves our treatment plant
it's drinking water standard and we try and keep it as
close to swimming pool standard as possible even though
it's outside."
After years of battling high fecal
coliform levels and bacteria that cause swimmer's itch,
the provincial government shut down the manmade lake for
18 months to dredge the bottom and install equipment that
can treat the lake's 45.5-million litres of water every
eight to 10 days.
The 26-year-old lake is now filled from
underground wells next to the Bow River every June and
drained after the September Labour Day long weekend.
Between 75,000 and 100,000 people visit the lake each week
of the summer.
Chestermere Lake, on the other hand, was
created as an irrigation pond in 1906 and now serves a
dual purpose -- a 750-acre reservoir along the Western
Irrigation District canal and a popular boating and
swimming destination for neighbouring communities that
have grown up around it.
Chestermere's total coliform levels were
far higher than any other lakes tested for the Herald, but
it is considered safe for swimming.
Chestermere's water is also tested
weekly for fecal coliform.
"We have excellent quality water
and we pay close attention to it because we have a lot of
recreational users as well as downstream users who need to
have safe water, too," said Heather Davies, a member
of Chestermere town council and chairwoman of the town's
watershed committee.
Unlike the other swimming lakes, the
biggest problem facing Chestermere Lake is the new water
constantly flowing into the reservoir. Channelled out of
the Bow River by the weir below downtown Calgary, tonnes
of sediment is deposited in the lake each year, providing
a nutrient bonanza for weeds and an array of heavy metals
and other pollutants that have been detected on the muddy
lake bottom in recent years.
"Ironically, the reason why the
water in this lake is so clear is because there are so
many weeds and they're doing what they're supposed to
do," Davies said.
"They're a pain in the butt for
users because the weeds wrap around your legs and arms,
but they are there for a reason, they do a good job of
filtering the lake."
Davies said the City of Calgary's
construction of new stormwater settling ponds near Shepard
to catch sediment before it flows into the canal will
dramatically reduce pollution levels, and the town also
hopes to secure funding to dredge 10 metres of soil
accumulation from the bottom of the lake.
"Once we get back to a depth where
the sun can't penetrate to the bottom it'll make all the
difference in the world for weed growth," she said.
"Our average depth is about 27 to
28 feet (8.2-8.5 metres) right now, but at one point it
used to be up to 40 feet (12 metres)."
Although he pays the membership dues
that grant him access to Midnapore Lake, Midnapore
resident Brian Pincott says he and his wife Barb Kinnie
never set foot in the 27-year-old water body because they
don't believe it is clean enough for swimming.
"We won't use the lake in the
summer, it's as simple as that," said Pincott, who is
a director of the Sierra Club of Canada's Chinook chapter.
"They build these artificial lakes
but there's no way to keep them clean without the natural
systems they need to cope," he said.
"The water quality in all of them
is suspect. I don't think it's worth taking the
chance."
Worries about water quality in Calgary's
lakes are compounded for critics such as Pincott by the
government's decision to loosen its regulations for
manmade lakes.
In response to lobbying by the managers
of Calgary's community-owned lakes, the provincial
government changed the Public Health Act last year to
raise the maximum allowable fecal coliform level to 10
times the former limit.
It's a move that was opposed by the
Calgary Health Region officials who argued manmade
community lakes should be held to a higher standard.
"We didn't see raising it that high
as a necessary step," Pelton said. "Being in the
business of public health, I like to see the standards
become more stringent over the years rather than loosened
up," he said.
"Once they're loosened up, then
somebody will come along and say they're still too
stringent and it can just get worse."
The change was made after lake managers
requested an end to differing standards for manmade and
natural lakes, saying manmade lakes shouldn't have to meet
stricter standards. Alberta's Health Minister Gary Mar
agreed, thereby increasing the maximum acceptable fecal
coliform limit to 400 CFU from 40 CFU.
"The logic behind the change was
that it didn't make much sense to have two sets of
guidelines if the bottom line is public safety,"said
Alberta Health and Wellness spokesman Howard May.
"If you're looking at the safety of
swimming in the water, if it's safe, it's safe, regardless
if it's manmade or natural."
Officials from Lake Chaparral
spearheaded the lobby group after lake quality tests done
for the Herald in 1999 found fecal coliform levels of 121
CFU in Lake Bonavista and 100 CFU in Lake Chaparral.
"Our concern was: Why were the
levels for lakes in the city different for those in the
rest of the province and the country? Was there undue
health concerns being portrayed to the community?"
asked Patti Coburn of Genstar's Lake Chaparral.
"The CHR really couldn't state why
they had those levels so we asked the government to
revisit them."
Coburn said lake managers argued that as
carefully controlled ecosystems, manmade community lakes
are typically maintained at higher levels than natural
lakes.
"Our lake is completely filled with
city tap water.
"The idea of something coming from
upstream and contaminating our system is unusual,"
she said.
Pincott said manmade lakes should be
required to meet a higher health standard because they are
built specifically for human use. He said he is disturbed
the change was made without public input.
"It was set at that level for a
reason and for us to see that it doesn't apply anymore
based on an industry lobby group is a bit much," he
said.
"Being a resident of one of the
lake communities, this directly affects me but we were
certainly not told about it or consulted in any way."
Independent water quality expert Dennis
Trotter said eliminating the difference made sense since
water quality tests are notoriously inaccurate.
"When it comes to public health
standards there's already a huge margin of error built-in,
just in case," Trotter said.
"The bottom line is it's very
difficult to draw the line between 40 and 400. You could
go out and take a sample in the bright sunlight at noon
and have virtually no bacteria and then take it later that
afternoon when it's cloudy and have 400 on the
other," he said.
"In either case, if someone was to
go swimming and drink a few millilitres, chances are they
aren't going to get sick."
While the standards may have changed,
Pelton said regular tests show there's no reason to
believe water quality in lakes is slipping.
"There isn't any concern of that at
this time," he said.
"This summer, even by the old
standards, levels are extremely low."
gsemmens@theherald.canwest.com
© The Calgary Herald
2004
