Article courtesy of Greg Mercer | July 25, 2015 | The Record.com | Shared as educational material
PUSLINCH LAKE — The lakeside scene beyond Art Zymerman’s dock looks like it was pulled from a postcard. But beneath the water’s surface, there’s a war going on.
Residents of Puslinch Lake have been fighting for years against an invasive species of weed called Eurasian water milfoil, and chronic sediment problems that have clogged their beloved lake and threatened to turn it into a swamp.
This month, they resumed a privately funded dredging project pulling an average of about 300 tonnes of mud out of the lake every day, their latest plan of attack that is costing them around $130,000 a year.
So far, the dredging, combined with annual chemical treatments, seems to be working. Using a barge manoeuvred by a tugboat, an excavator has been digging out the lake’s silty bottom, and hauling the sediment to shore where it’s trucked to dry in a nearby field.
Last year, they hauled about 24,000 tonnes out of the lake. This year, they hope to do upward of 28,000 tonnes. But that creates a new problem: Just what do you do with all that sediment?
That answer is not yet known, but for Zymerman and others with property around the lake, losing this battle isn’t an option. If the silt and the weeds win, they say it’ll be the end of the fishing, boating, swimming and water skiing the local lake just south of Highway 401 is known for.
“I think most sane people would have walked away from this a long time ago,” said Zymerman, president of the Puslinch Lake Conservation Association, created by homeowners in 1997. “It’s just been one thing after another.”
Both nature and people share some of the blame for the problems with Puslinch Lake. Formed by retreating glaciers, the shallow kettle lake has no natural flow of water in or out. Run-off from old septic systems and farming operations flushed into the water, and compounded the plant growth.
About a decade ago, the Eurasian milfoil started appearing in the lake, and soon began choking it out. The weed, native to northern Europe, is thought to have been brought to North America in the 19th century in the ballast of ships.
Today, it’s one of the most widely distributed invasive aquatic plants on the continent. It forms dense underwater mats that shade other aquatic plants, and can begin to reduce oxygen levels in the water, pushing out native species and killing fish.
This summer, the fight against the milfoil infestation and the sediment continues, one scoop at a time. It’s believed to be one of the few inland lake dredging projects in North America, and the homeowners have had to jump through a maze of regulatory approvals to do it.
The dredging means less sediment and fewer nutrients to feed weed growth, making Puslinch Lake deeper and cooler, which also slows plant growth. And since the kettle lake is self-contained, there’s an awful lot of mud that has collected at the bottom over the centuries.
“There’s 10,000 years of silt in that lake,” said Dave Taliano, the project manager and the lake resident who came up with the dredging plan.
“The mud we’re pulling up is like nothing you’ve ever seen. It’s an organic, spongy blend of fish, plants, shells and everything else that has decomposed since that lake was formed.”
The dredging also means things that have fallen into the lake since it became a popular summertime playground in the late 1800s are being found again. These include hundred-year-old bottles, a silver spoon, even a vintage water ski from the 1960s, all preserved in the mud.
The residents have discovered that the lake is deeper than previously thought. In some places, the mud is believed to be in excess of 16 metres deep, and they’ve discovered underwater ridges and valleys that have never been mapped.
A big barge docked a short walk from Zymerman’s house is the homeowners’ main workhorse. Using two 14-metre “spuds” that hold the barge steady in the water, an excavator on-board digs down about six metres below the surface and hauls up the sediment.
When a holding bin on the barge is full, the tugboat makes for shore, where the sediment is trucked to a nearby field, dumped, and left to dry.
An agreement with the Grand River Conservation Authority promises not to stockpile the mud on the site. That means the homeowners have to get rid of it as fast as they can, which is why they offer it up to anyone, for free.
There’s been some interest from farmers and aggregate companies, but not enough to clear all the sediment they’re pulling out of the lake. The amount of mud they intend to remove this year is enough to fill some 1,400 dump trucks.
Zymerman says the sediment has tested clean for contaminants and is “better than compost in some ways.” But because it’s mostly clay, it needs to be mixed with other soil or compost for gardening — and the homeowners aren’t allowed to process the material themselves.
“We’re not allowed to sell it, and we have no intent to do that. We’re not turning this into a manufacturing process,” he said. “The only problem is it weighs a lot … We have to find a way to get rid of it, and that’s one of our missions today: Who will take this stuff off our hands without us having to pay for the trucking?”
Hauling the sediment away from Puslinch Lake would cost another $100,000 a year, money the homeowners’ association doesn’t have, Zymerman said.
Saving Puslinch Lake has been a long and expensive battle. A few years ago, residents spent $100,000 on weevils, the tiny beetles that feast on the milfoil plant. The bugs seemed to help the problem, but Zymerman said the homeowners decided they couldn’t afford to dredge the lake and keep stocking it with weevils at the same time.
And there was another problem — the weevils were an abundant source of food for bluegill fish, whose population exploded in the lake.
“We fed the fish,” Taliano said. “Our lake was full of them.”
Ultimately, the homeowners approved a much more affordable plan to attack the milfoil with an aquatic herbicide called Reward, which has shown noticeable results, he said.
An earlier dredging project started by the Puslinch Lake Conservation Association in 2000 used hydraulic equipment that pumped sediment into onshore holding ponds. But concerns about possible contamination in the post-Walkerton era ended that approach in 2009.
Three years ago, the residents settled on a new plan, proposed by Taliano — they would dig a series of deep holes in the lake, which would lower the overall depth and cool down the water. They paid about $350,000 for the dredging equipment, plus the annual costs to run the operation.
Almost all of that expense has been covered by a few dozen property owners, save for some small corporate grants, a little help from the township and a $50,000 Trillium Foundation grant. They’ve held fundraisers, solicited donations and repeatedly hit up residents for pledges.
For the next few months, the dredging will continue all day long, five days a week. It’s tedious work. The barge can only move a little under two kilometres an hour, and breakdowns are frequent because the equipment is working in water.
“It’s a very slow process, and the challenges are extreme,” said Taliano, who had to form a company, Express Dredge Service, to do the project. “But I was at the point where if we couldn’t get it fixed, I was moving. Who wants to live on a swamp? So I found a way to fix it.”
The improvement has been night and day, say homeowners.
“We’re taking the lake back 200 years,” said Taliano, a resident for 15 years. “There’s been a massive change. Five or six years ago, no one would move out here. Now we’ve got beautiful water again, the weeds are under control, the sediment is under control.”
When Zymerman and his wife bought their waterfront property about 11 years ago, he was shocked the first time he saw the weeds choking out the surface of the water.
“It was basically a carpet of gold,” he said. “It was everywhere.”
The milfoil was so thick beyond his dock that it clogged his powerboat when he tried to ride across the lake. Today, Puslinch Lake is blue again, more like the lake he used to know.
“We’re not doing this for us. We’re doing it so our kids, and our grandkids, can enjoy the lake,” Zymerman said. “It hasn’t been easy. But that’s what makes it worth it.”