Field Notes
Field Notes

Wind, waves, and water science

Monday, March 30, 2020
Posted by
Greg Seitz

Rollers at sunrise on Lake of the Woods, late October 2019.

The bow of the boat rises and falls as it crosses silver waves, the deck pitching and rolling. Sometimes we slam into one and water sprays across the deck, sometimes we come off a crest and slap down, splashing into the frigid lake.

The spray freezes where it lands. A thin coat of ice covers all surfaces, including our coats and life jackets.

Dr. Adam Heathcote is driving, twisting and turning across the water, trying to avoid direct hits, steering and working the throttle to plot our course as smoothly as possible.

It isn’t very smooth. The crew says these are the worst conditions they’ve ever encountered.

It’s late in the afternoon, late in October, and we are the only boat that appears to be out on vast Muskeg Bay, or maybe the whole southern basin, of Lake of the Woods. The temperature is in the twenties, and a stiff breeze from the southwest sends endless waves wandering toward us. Dr. Mark Edlund is Adam’s partner and co-pilot, both of them scientists at the St. Croix Watershed Research Station, part of the Science Museum of Minnesota.

This adventure is being undertaken with funding from the Minnesota Pollution Control Agency to help develop realistic water quality goals on this important lake, and find the best methods for achieving them. The MPCA’s Cary Hernandez is aboard for the first two days on the lake, dragging buoys aboard and freezing along with the rest of the crew.

We will head back to the landing, back to steady ground, out of the wind and spray, back to dinner and a beer in Baudette, only after we’ve pulled some sensitive instruments from under the water.

Lake of paradoxes

Left to right: Mark Edlund, Adam Heathcote, Greg Seitz

This huge lake is full of walleye — and contradictions. It is more popular for fishing in winter than summer. Its bedrock geology bridges the basalt of the Canadian Shield to the north and east, and the sands of Glacial Lake Agassiz to the west and south. It contains both broad sheets of water and rocky island-studded channels.

And, crucially, even though paper mills and sewage treatment plants have largely stopped dumping nutrients into it since the 1970s, Lake of the Woods is still plagued by cyanobacteria blooms that turn the water green and possibly toxic.

Cyanobacteria are ancient organisms — billions of years old, they were the first forms of life to use energy from the sun. They’re found almost everywhere on Earth, in harmless low numbers. But when they burst into a big bloom, driven by nutrients, weather, and other forces, they cause big problems. On Lake of the Woods, this has caused the deaths of multiple pet dogs, who died after swimming in water full of toxins produced by cyanobacteria.

Adam Heathcote observes Lake of the Woods during a cyanobacteria bloom on an earlier research trip. (Video by Mark Edlund)

Unlike most Minnesota lakes with cyanobacteria problems, Lake of the Woods is not surrounded by farm fields or cities that dump large amounts of nutrients into its water. This is wild country comprised of bogs and lakes, forests and rivers. Only 12 percent of the land that drains toward the huge lake is used for agriculture, while eighty percent of the watershed is open water and wetlands. Most of the lake’s tributaries in the Minnesota portion of the watershed meet state standards for water quality.

Yet cyanobacteria in the lake seem to be a bigger problem every year.

That’s why we’re here on this cold and lonely trip. By placing sensors in the lake for almost the whole open-water season, scientists can see when blooms happen, what the water is like before, during and after a bloom, and much more.

Hopefully it will all help government agencies, tribes, nonprofit groups, and private citizens from two countries restore and protect this special waterbody.

First we have to brave the waves and find the buoys.

Search and retrieve

Mark Edlund prepares water samples while Cary Hernandez of the MPCA (at right) assists.

Most of the equipment has been out here since June, taking measurements of a variety of water quality variables every 30 minutes, from temperature to oxygen levels and more. The devices made from PVC pipe collect sediment, gathering a record of the amount and type of nutrients, algae and other material suspended in the water.

All that information is still below the surface of the lake.

Crossing miles of Muskeg Bay, we can only pull hats and hoods over our faces and ride with our own thoughts. The noise of the wind, water, and the motor rules out conversation. Adam watches the waves while the rest of us watch a little triangle crawl across the screen of the GPS display, tracking our position, following a laughably straight line toward the next coordinates.

We ride — winding and weaving through the waves, rising, falling, pitching, rolling, slapping, spraying, splashing.

Mark Edlund hauls a sediment trap on board.

Each site exists as a virtual speck — a set of GPS coordinates — and as a physical manifestation — contraptions consisting of sensors connected by yellow polypropylene ropes, submerged and anchored at or near that location.

The buoys have nothing above the water, but there is a float at the top of the rope, a few feet below the surface. The bright yellow line goes down through the water to cement blocks on the bottom. Tied on at various depths are sensors and sediment traps.

The first job when arriving at the coordinates is to find the thing.

Once a month all summer, Adam, Mark, and a rotating crew of helpers visited the sites, downloading data and collecting samples. On a sunny day with relatively clear water, the crew could sometimes see the float through the water as soon as they arrived.

Today is different.

Swerving and snagging

Passing Gull Rock at sunset.

The low angle of the late October sun, the gray skies, and the waves, make it impossible to see below the surface. We hope to spot the float pop out in the trough of a wave, but that does not happen.

The boat’s GPS takes us from Arnesen’s Rocky Point Resort to the first study site. When we get close, navigation switches to a small hand-held GPS device that shows the precise distance and direction to the coordinates. One person watches it, reading out the information for Adam at the helm, and he swerves through the waves, trying to get there but not overshoot.

“Fifty feet straight ahead.

“Thirty feet starboard.

“Ten feet ahead.

“Three feet starboard, throw!”

Mark throws out a small buoy with a light anchor line to mark the spot. On such a vast expanse of water, where the shoreline is out of sight to the north and barely visible to the south, a point of reference on the water makes it easier to know where to look.

Mark Edlund attempts to snag the buoy with a line attached to a large treble hook.

Then, while Adam and the GPS reader try to navigate back to that buoy, Mark stands in the bow with a huge treble hook attached to a rope. When we are close, he tosses the hook overboard, hoping to snag one of the lines on the submerged buoy.

It takes several tries in these rough seas, with Adam needing to circle the boat around and come back toward the site again and again. We climb and fall on the waves.

Once Mark finally gets hold of the line, the work begins.

Mark hangs over the side of the boat, pulling on the yellow line connected to the high-tech instruments and the anchors. He drags them aboard, everything covered in slimy algae. Mud and algae now freeze to the boat along with the ice.

It can be an intense and challenging process, but everything is eventually brought aboard. Then Mark collects water samples while Adam uses an instrument loaded with all kinds of water quality sensors to take a spot check of conditions at the site.

Constant data collection

Adam Heathcote takes water measurements at a study site.

The first site gives us everything the lake has to offer: ice and waves, cold and wind. At least we are fresh. After wrapping up there, it is another five miles to the second site, another half-hour hunched against the wind. When we get there, the sun begins to set and the challenges are no longer novel.

We circle the spot, Mark throws the hook again and again, and then pulls equipment aboard, performing complicated tasks with frozen fingers. The whole effort might seem crazy, but our salvation is that the crew has done this job many times before. No time is wasted.

And the effort is paying off with the kind of data and insights never before available on this huge lake, nor many other valued waterbodies.

Cyanobacteria blooms on Lake of the Woods were almost nonexistent in 2019. A Canadian environment agency has used satellites to track algae on the lake since 1985, analyzing the extent each summer. This year showed almost nothing.

Satellite analysis of the lake, with warmer colors showing higher inferred levels of cyanobacteria. Left to right: August 29, 2004, September 7, 2016, October 17, 2019.

While the satellite watches from far above, the sensors submerged in the water gather massive amounts of information about conditions in the lake. Combined with climate data and much more, the complex connections in the water start to take shape.

The story of the past summer was cool weather and high water. With trillions more gallons of water in the lake than average, all the nutrients, cyanobacteria, and toxins were diluted.

The minor peak of the year’s algae growth had actually occurred just two weeks before our frigid foray. It almost always reaches its maximum in October or September. That’s one reason why it’s valuable to leave the monitors out as late as possible, to make sure they don’t miss the bloom, so that’s one reason we’re out here in such unpleasant conditions.

The way the lake varies each year is important. By doing this long-term continuous monitoring, the scientists can start to separate real trends from natural fluctuation.

Last but not least

When the buoys at the second site are on board, we pull anchors and settle back into our seats. There is a narrow band of clear sky between the horizon and the cloud cover, so we can see the sun dropping below the horizon. There are a few miles of water between us and the landing.

Adam drives us southwest back toward Arnesen’s, watching the horizon glow. We pass Gull Rock, a hunk of granite that is a rare landmark in this big basin. We bounce off more rolling waves.

It’s nearly dark when the boat bumps into the dock. We move stiff muscles to unload all the gear and samples, and get the boat loaded back on its trailer. Then we go to Rosalie’s Diner in Baudette for wild rice and walleye, two priceless resources of Lake of the Woods, both requiring clean water. The Castle Danger Cream Ale that washes it down likewise depends on the pure waters of Lake Superior — the only body of water in Minnesota that is larger than Lake of the Woods.

Clean water bounty.

Then we sleep. At breakfast each day we are joined by the railroad and electrical line workers who frequent this hotel. Everyone drinks a lot of coffee.

We get the third and final buoy with a little help from our friends. This one is located in the hardest possible position based on the wind direction and our boat landing options, so Shane Bowe of the Red Lake Department of Natural Resources brings up a boat with a cabin and other luxuries.

It’s early when we launch at Wheeler’s Point, where the Rainy River flows into Lake of the Woods. The sun is just coming up over the Canadian shore when we leave the landing.

The wind and waves don’t get serious until we pass through the gap between two of the barrier islands that shelter the river’s mouth. This international archipelago also happen to host one of the only beaches in Minnesota or Ontario where endangered piping plovers breed.

Then we are exposed to the lake, which apparently did not settle down overnight as we hoped.

Turning back isn’t really an option. This buoy is the only one with a new sensor attached that records the levels of cyanobacteria cells in the water. Samples were collected during each visit to measure the amount of toxins in the water and the scientists hope to compare this to the abundance of the algae that produce them. A key question about cyanobacteria is when toxin levels can be dangerous even if there’s no visible sign of a bloom.

In this year when the satellite showed little algae growth, it will be useful to see if there were still toxins in the water.

So we have to get that instrument. We speed northwest, right into the waves, it is spine-jarring. I am glad to have apparently passed the “will-I-get-seasick” test so far.

It’s the eastern horizon’s turn to glow. Morning mist is whipped over the waves by the steady wind, all of it lit by the rising sun. We’re the only people to see this particular sunrise in this particular place, and it makes the cold and the waves worth it.

Adam and Mark wrestle a buoy aboard from the bow of the Red Lake DNR's boat.

Once more we get to the site, throw the hook, finally snag the buoy. It gets wrestled onto the boat, samples are recorded, and we turn tail and retreat to shore. The field season is done, a winter’s worth of analysis awaits.

By comparing how toxin levels rose and fell with measurements of cyanobacteria, the amount of light reaching through the water, and more, the team will start to see how water, nutrients, wind and temperature, interact.

Only constant observation can provide such insights into how the lake functions, and why cyanobacteria blooms occur.

The continental breakfast is still being served back at the hotel. We get more coffee, grab our luggage, load everything up, and hit the road home. Dozens of computer chips in the bed of the truck contain countless pieces of information representing months of changes across the wild waters that will soon be locked in ice.

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

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