Editor's note: This article was originally published Sept. 30, 2018.

DEVILS LAKE-At first glance, the image on the depth finder screen looks more like the surface of the moon than the bottom of Devils Lake.

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To Bruce "Doc" Samson and Warren Parsons, both experts in the ways of sonar, mapping and imaging technology, the picture tells the story of a battle lost in trying to stave off the advance of a rising lake.

The image, captured as a screen shot and stored on a tiny chip, shows an extensive row of rocks and what once was a swimming pool now submerged under more than 12 feet of water at the bottom of Creel Bay.

"As the water went up, he was probably trying to save his house, which was right by the swimming pool," Samson says, pointing to a screenshot of the image.

The rocks likely were placed in an effort to protect the property from the rising lake, Samson speculates.

Probing the depths of Devils Lake has been a passion for Samson and Parsons for years, but advances in underwater sonar technology from companies such as Humminbird and Lowrance-two of the biggest names in fishing electronics-have taken their discoveries to new levels.

Or, more accurately, perhaps, new lows.

Trailer house frames, marinas, swimming pools, concrete slabs, foundation footings, old farm equipment and trees by the hundreds are among the discoveries they've made with sonar, side-imaging and down-imaging technology.

"Warren likes it for the historical stuff; I like it for the fishing," Samson said.

Call him 'Doctor Sonar'

Known in the industry as "Doctor Sonar," Samson, 69, is a Cavalier, N.D., native and UND graduate from Osakis, Minn., who retired as a physician in 2003 to become a full-time fisherman.

A member of the Minnesota Fishing Hall of Fame, Samson is one of the winningest anglers in the history of professional walleye fishing. These days, he's cut back his tournament schedule to focus on teaching others how to use sonar, down-imaging, side-imaging and digital mapping technology to "see" the bottom of the lake and catch more fish.

Samson recently partnered with walleye pro Johnnie Candle of Devils Lake to offer a two-day Walleye School in Devils Lake that filled to capacity.

"I have a lot to share with knowledge of sonar and I simplify it for them," Samson said. "I'll do sidescan, downscan, sonar and teach them to interpret what they're seeing."

On a recent September day before the Walleye School, Samson and Parsons offered a crash course in sonar and mapping, sharing some of their Devils Lake discoveries over breakfast at the White House Cafe before heading out in separate boats to map other parts of the lake.

Samson also found time to wet a line, something Parsons rarely does.

"If I stopped to fish, I'd never get anything done," he said.

During the breakfast session, Samson points out the image of a series of rock piles, stored in a tiny chip and displayed on the depth finder screen.

The sonar actually casts a shadow, similar to a spotlight, behind the rocks, revealing them as large boulders, perhaps riprap protecting a driveway from the rising lake.

"See the shadow? Look at the size of the boulders," Samson says. "Those are piles of rocks, and there are fish in there. I know because I caught them."

Hooked on DL

Parsons moved to the Lake Region from Forest Lake, Minn., more than a decade ago so he could spend more time mapping and probing the depths of Devils Lake. Just shy of a geography degree at UND, he later worked as a survey technician for the Minnesota Department of Transportation, leaving that job in 1998 to concentrate full-time on mapping lakes.

He knew little of Devils Lake until joining Samson on the water before a fishing tournament in May 2004.

With Parsons' assistance, Samson markets a line of instructional DVDs and digital maps under the Doctor Sonar brand, including several for various portions of Devils Lake.

"Warren does most of the mapping," Samson said. "I'm the motivator."

Parsons has merged the sidescan and downscan images of many of his underwater findings with the digital maps he's created on the water and historic photos-complete with contour lines-showing what the landscape looked like in 1949 and 1990 before the water came up.

Six-Mile Bay, for example, basically looked like a swamp in the 1949 photos.

"He's an expert at taking these photos and making them accurate for GPS," Samson says. "We're only showing the good stuff on the map because it takes so much data."

It's kind of like putting a jigsaw puzzle together, Parsons says.

"Bruce is after fishing, and I'm after seeing what was going on down there," Parsons said. "Like, 'OK, here's all these rocks. Why is this path in the middle of it?' "

Not surprisingly, given the variety of submerged structure at the bottom of the lake, their Devils Lake chips are the most popular among anglers.

Parsons calls up another screenshot that had him scratching his head until he put an underwater camera through the ice, when visibility is best.

"Those are the remains of trailers," he said. "That's just the frame.

"We actually got lucky and landed right in the middle of them" with the camera, he said. "One, I think, was a really huge trailer. This area is full of things like that."

Another time, Parsons recalls coming across rows and columns of what he thought was an orchard.

The underwater camera revealed a different picture.

"I went out there with the camera last winter, and they're actually footings," Parsons said. "It must have been a big building."

CHIRP, for short

The technology Parsons and Samson use on their boats allows them to pick up images of rocks or other submerged structure as small as softballs, Parsons says.

"It's fairly accurate," he said. "It's not like shooting a bullet through an eyehole. It's more like horseshoes and hand grenades. But if you've got a (GPS) coordinate, you can take your waypoint and drive up to it."

In the very simplest of terms, the sonar uses a fairly new technology called CHIRP-Compressed High Intensity Radar Pulse-which transmits multiple signals from the boat's transducer at varying frequencies instead of one set frequency, in turn providing a clearer picture of whatever the signals hit below the water.

Side-scan transmits two beams, one out each side of the boat, while downscan transmits a single beam. The electronics Samson runs in his boat-a Humminbird Helix 10 and two Lowrance HDS 9 units-can be set to operate as imagers, GPS maps, regular sonar units or in a split screen format, offering an even broader picture of what's below.

It's all about bringing the bottom of the lake into focus and, ultimately, catching more fish. Given the size of Devils Lake, there's more down there just waiting to be discovered.

"You have a better picture of the bottom" with side-imaging, Samson said. "It makes more sense now."

• On the Web:

For more information on "Doctor Sonar" maps and instructional videos, go to www.doctorsonar.com.