By Timothy R. Olsen ’09, ’18 MBA

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In the spring of 1997, the heavens opened and severe flooding rocked south-central Texas. More than a dozen counties were designated Federal disaster areas and millions of dollars of damage were inflicted. 

After the flooding, an investigation into the stability of the Wirtz Dam in Horseshoe Bay, Texas, roughly 55 miles northwest of Austin, revealed a massive hole below the spillway, which had opened all 10 of its gates for the first time during the event.

With long-term forecasts indicating the potential for greater flooding the following year, this was a serious concern.

Enter the Utah Water Research Laboratory.

Contacted by consulting engineers from the firm Freese and Nichols, the UWRL built a 1:35-scale model of the dam in their Logan facility. Using the model, they were able to show how concrete pads placed at the base of the spillway could deflect the flow, shifting the energy dissipation downstream and protecting the bedrock.

“Responsible design says let’s minimize risk or uncertainty as much as we can,” says Civil and Environmental Engineering professor Blake Tullis, a 1990 USU graduate who worked on the Wirtz Dam project. “That often involves doing a physical model in a facility like ours, and there’s not too many of us in the country.”

This modeling, combined with additional testing done to create an alternate gate operating sequence, resulted in millions in potential savings. A fact that was even celebrated by a headline in the November 10, 1997, issue of the Austin American-Statesman.

That same fall, Dustin Mortensen was just beginning his educational journey at USU. Born in Delta and raised mostly in Richfield before moving to Pleasant Grove in high school, Mortensen first visited Utah State as a participant in the university’s Engineering State program. After that visit, he knew he was going to be an Aggie. 

“I spent the week at USU in one of the towers, did all sorts of engineering activities, made good friends, and experienced Logan and USU,” Mortensen recalls. “After that week I decided that’s where I was going to go.”

Mortensen says he’d always kind of leaned towards civil engineering, but that once he was on campus, three individuals — professor Michael Johnson, associate professor Steven Barfuss, and Tullis — really influenced his focus on dam engineering.

Johnson, who was teaching an intermediate fluid mechanics class at the time, says school came easy for Mortensen. He remembers a story recounted to him from some of Mortensen’s classmates about how they’d scribble notes frantically during the class and often leave confused, whereas Mortensen would simply sit and pay attention and seemingly master the concepts. 

“Dustin is a fellow who is quick to observe what’s going on in a process, and I think is fairly methodical with what he says and what he does. He is very sharp at processing the situation and then acting in real time in terms of what’s needed,” Johnson says. “There are some people who are very aware of what’s going on. They see more than just themselves, and I think that’s Dustin. He’s good that way.”

For Mortensen, who graduated with his bachelor’s in 2003, the initial plan wasn’t to stick around for a master’s. However, the combination of USU’s unique engineering program — which has a one-year add-on master’s track — and an offer from Johnson to design and build a physical model of a spillway structure were too much to turn down.

That project also involved Freese and Nichols, the same engineering firm the UWRL had worked with in 1997, and the company Mortensen now works for.

“I’ve got a guy here who’s pretty good, you ought to consider hiring him,” Johnson recalls telling his contacts at the firm. “[Mortensen] interviewed and I reached out to my friend after the interview and he said he didn’t interview very well. I said, ‘Really? Well hire him anyway. You won’t be disappointed.’

“I got a call back in about three months and they said, ‘Do you have any more like him?’” 

Now, nearly 30 years since Utah State was brought in to consult on the Wirtz Dam, Mortensen is wrapping up construction on a new dam in North Texas. One that just began filling in July and will provide much-needed water for an area of major expected growth.

The roughly 2.3-mile-long Leon Hurse Dam — part of the Lake Ralph Hall project — includes a unique spillway that was tested in the Utah Water Research Laboratory. According to Tullis, this project was the first to combine a labyrinth weir design with a stepped spillway chute.

A labyrinth weir is a type of low dam with a zig-zag shape across the top which helps control how fast the water flows. The longer edge created by the sawblade-like shape, as opposed to a straight line, helps keep the water behind the dam from rising too high and flooding the banks during heavy rain. It also allows for water control with no moving parts, using only gravity and the unique shape.

As for a stepped spillway it’s exactly what it sounds like … steps that the water spills over. This helps dissipate the water’s energy as it tumbles down over the dam before reaching the bottom — in this case a fair distance.

“It was a little bit unique to have the crest of the spillway be a labyrinth with a steep stepped chute, and transitioning the water from that complicated crest into the step chute was a little bit unique,” says Civil and Environmental Engineering associate professor Brian Crookston who worked on the project. “We added some features that really helped with that transition.”

For Mortensen, the project meant a relocation in 2021 for he and his wife, Melissa — a 2003 psychology graduate — and their four sons. While it was a change to leave Austin, the place they’d called home since 2004, it was an opportunity to shape the future and create lasting impact. 

“It’s really neat to be involved with a project like this that changes the map,” Mortensen explains. “When you look at a map and a new lake this size shows up, that’s something. “It’s going to be here a lot longer than any of us will. Lakes last a long time. … It’s just neat to be involved with something so much bigger than me.”