SYLVAN LAKE — Among the many interesting photos unearthed for Sylvan Lake’s centennial celebrations were old beach shots from the early 1940s.
The photos show throngs of sun lovers staking out their claims on a wide strip of sand out of which cropped a long wooden pier and large rental boathouse and snack shop.
Flash ahead 70 years and the boathouse and pier are long gone.
But so is the sand.
Sylvan Lake now laps at the concrete sea wall at the edge of the provincial park, much to the consternation of those who relish the good ol’ sand castle days.
Research by Alberta Environment and Sustainable Resource Development hydrologist Terry Chamulak shows Sylvan’s big beach days are more rare than many might assume.
In the early 1940s, the lake level was about 936.3 metres above sea level, which is unusually low.
A 1978 study determined that ideal lake levels for 60 metres of beach is in the range of 936.27 metres elevation.
“Historically, if you look at the water levels for Sylvan Lake going back to 1940 to the present, the lake has very seldom been in that target range,” says Chamulak.
Except for the mid-1960s, a few years in the 1980s and around 1990, it’s never been in that range.
“People think the target range, which is ideal for a beach … a regular occurrence. It’s actually very rare.”
The town used to meddle with Mother Nature to restore the beach in the 1980s by using graders to dredge up sand. The idea was recently broached again, but Alberta Environment said no way.
There has also been some talk among lakeside communities about improving the flow of the outlet channel — what is known as Sylvan Creek in the southeast corner of the lake — but nothing has been decided and there’s a potential for causing flooding problems downstream.
This summer, the town has built a beach area on park land to give people a sandy alternative.
While beach-friendly lake levels are rare, the amount of water in the lake in recent years has also been uncommon. The lake was at an all-time high in 2011, reaching 937.049 metres.
The question of why the lake is so high is complex, says Chamulak.
“Every lake is unique really. However, when you see a trend in a region, it typically reflects climate.”
However, when Chamulak checked precipitation records for stations around Sylvan Lake he found precipitation was no higher than usual. In fact, to his surprise rainfall levels were below normal averages.
What is likely happening, he deduces, is that there are more extreme weather events occurring. There have been more torrential downpours, but because of their localized nature that rainfall is not always recorded by the network of climate stations.
“Climate stations are a small plot of land, maybe 10 metres. And if the storm doesn’t go over that it misses.”
Streamflow gauging stations though cover a wider area. Chamulak looked at three gauging stations, two on the Blindman River, northeast of Sylvan Lake, and on the Medicine River, west of Sylvan Lake. They cover almost 4,000 square km of water catchment area.
“What is interesting is I’ve noticed very, very significant increases in stream flows in the years that these lakes have risen dramatically.
“All three gauging stations are showing significant stream flows — double or triple the normal average for a year in terms of volume of water (versus long-term average).”
For instance, in 2007 when Sylvan Lake’s levels really began to rise noticeably, the Medicine River station recorded stream flows 272 per cent above normal. On the Blindman River, flows were 199 per cent above normal.
“The last few years for Sylvan Lake have been above normal for stream flow runoff, but not precipitation.”
In 2011, when Sylvan Lake reached a historic peak, the climate station on the Blindman River near Bluffton was 164 per cent above normal. On the same river near Blackfalds, the station recorded runoff 231 per cent above normal annual levels.
The Medicine River near Eckville was 223 per cent above normal.
Another factor may be significant land use changes around the lakes.
“We’re getting a lot of development here. What’s happening is landowners are draining their potholes and sloughs. So what that’s doing is that instead of trapping that water we’re getting more water that is running off.
“So even though you have average precipitation, even below-normal precipitation, you have more water running off.”
Some of that is to improve agricultural productivity, but some is to clear land for development. Forest canopies have also been whittled down, and new roads mean more runoff.
Similar factors have also led to increases in Gull Lake’s levels.
So, when can Sylvan Lake expect to see its beach return?
Probably in a few years, says Chamulak. Sylvan Lake’s levels seem to rise and fall on roughly 10-year cycles. The last time lake levels were quite low was 2007, so around 2017 could be the next low.
“I would say if history repeats around that time we could be back to those desirable levels.”
But for the optimum lake levels for a good beach to be reached, a few things have to go right. Since the lake’s outlet is at 936.7 metres, the lake will never drain enough to reach the 936.27 range for the best beach. Getting that low means lots of evaporation will be required, so the weather must co-operate as well.
Mayor Susan Samson has taken the view the lake is best left to its own devices when it comes to beach fronts.
“I think as stewards of the lake we have to recognize what our role is and we can’t change nature. We have to learn to live with the lake levels,” she said earlier this year.
And besides, lower lake levels sometimes means warmer water and blue-green algae can become a problem.
“You have to be careful what you wish for.”
Lacombe County council also debated the merits of tinkering with the outlet creek to improve flow and, hopefully, reduce lake levels.
Coun. Brenda Knight summed up the presiding sentiment.
“Mother Nature knows best. Leave her alone — she’s got the ultimate power.”
pcowley@www.reddeeradvocate.com