More than 5,000 athletes will be in Milwaukee this weekend for the 2026 USA Triathlon.
The athletes will be dipping into Lake Michigan as part of the competition. And thanks to a local researcher, they’ll know exactly what the lake’s temperature is before they take the plunge.
Todd Miller squeezing in time on the water before joining students on campus. He teaches in UWM's School of Freshwater Sciences and Zilber College of Public Health.
“I have to go up to my main lab on campus and help students with the fish, looking for algal toxins in fish,” Miller says.
Miller’s research focuses on blue-green algae. It can produce toxins that are harmful — not just to fish but other life, including humans.
Part of that research includes monitoring lakes.
In 2010, Miller and his students started designing and building small, solar-powered buoys to collect data on the presence and pervasiveness of blue-green algae.
“Lake Winnebago was our first project, monitoring algal blooms in real time. We’ve come a long way since then," Miller says. "They were pretty crude buoys back then — large, difficult to manage. Electronics that were inefficient. But over time we made them much more efficient, made buoys smaller, more easily deployable."
He dubbed the buoys “Panther buoys” — after the UWM mascot.
Over time they’ve been put to work in other inland lakes and as far away as the Apostle Islands.
In 2013, Miller was tapped to collect data — not for algae, but water temperatures — when the USA Triathlon came to Milwaukee, and would be competing in Lake Michigan.
“We were working with the health department to do monitoring of water quality, and they asked for water temperatures. Normally, people will take an instrument and drop it into the water, measure water temperature one time on a given date. So, we did that for them on several dates leading up to the event,” Miller says.
The next year, the triathlon returned to Milwaukee. Miller proposed using buoys to measure the lake’s water temperature every few minutes.
“[The race organizers] said yes, it would be very useful," Miller says. "Contestants would really like to look at that data. So, students and I put together a very small buoy with electronics that we had designed and built, and we deployed this small buoy in the Discovery [World] lagoon for them."
That’s where athletes would be competing.
“They jump in the water at the Discovery World dock and then they head out under the bridge into the Summerfest lagoon area and then back. This lagoon during this race is just boiling with swimmers,” Miller says. “Pretty cool to watch.”
Miller deployed that same, well-maintained buoy a couple of months ago leading up to this weekend’s triathlon.
“So, it’s measuring water temperature with a sensor that students and I made that has digital temperature sensors at four different depths, from the surface — 0 feet — to 10 feet,” Miller says.
The 25-pound buoy is 2 feet in diameter, standing 3 feet tall. Its sensors are mounted beneath, while three small solar panels up top capture sunlight to provide continuous power.
Occasionally Miller hops on a small School of Freshwater Sciences vessel to check on it.
“There’s been a few times where the buoy has disappeared and then reappeared, many times where we’ve seen it not in the location where we dropped it. I think kids at night like to swim out there and play around,” Miller says.
We arrive and the buoy looks ship-shape.
“Looks good! Data’s coming in,” he says.
Miller says triathlon participants start checking the data as soon as the buoy hits the water. They just click a link provided by event organizers to tap in to the live tracking.
“They might be coming from Arizona and might be their first time in a Great Lake swimming, so they’re quite interested to know what they’re in for,” he says.
Temperatures can be tricky, even in August.
“We can have cold water come up into the surface water and cool things off rather quickly in nearshore waters,” Miller says.
Brian D’Amico, USA Triathlon event director, stands on the Discovery World dock.
In a few days athletes would be diving in, in waves of 75 to 200 people at a time.
D’Amico calls Miller’s contribution to the competition unique.
“There’s not any races that I know of that put a buoy such as this out where they can see different temperature reads. So really that data is really invaluable,” D’Amico says.
And it's practical. The temperature determines whether wetsuits are required, optional or not allowed.
“There’s a temperature range of about 16 degrees or so,” D’Amico says. If it's at or below 60.6 degrees Fahrenheit, “It’s mandatory athletes have to wear wetsuits. If it’s about a certain degree – 76.8 – wetsuits are forbidden.”
When this story was produced Tuesday afternoon, the surface temperature was 73.25 degrees Fahrenheit – meaning wetsuits would have been optional.
You can check for yourself here.
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