WESTBROOK — Dozens of triathletes from across Maine and the country who will be competing in the Presumpscot River this weekend will have bragging rights after swimming in waters where a giant snake, nicknamed Wessie, has been spotted.

T-shirts that read “I Survived Wessie” – the artwork features an image of a grinning snake and swimmer – will be sold Saturday during the Major League Triathlon race that is part of a daylong festival in Westbrook’s Riverbank Park.

Several snake sightings have been reported in the park and a large snakeskin was discovered near the river on Aug. 20. Westbrook Police Chief Janine Roberts sent the snakeskin to an associate professor of biology at the University of Texas, where DNA tests determined that it belonged to an 8- to 9-foot, juvenile anaconda. Professor John S. Placyk Jr. said anacondas are not venomous and pose no threat to humans. A bite from an anaconda is painful, but not fatal.

Daniel Cassidy, the CEO of Major League Triathlon, and his wife, Sarah Cassidy, are using the snake to promote the triathlon and plan to award race winners a 4-foot stuffed anaconda toy. The Westbrook Community Center will receive 10 percent of the proceeds from T-shirt sales.

“We are embracing it (Wessie) full throttle,” Sarah Cassidy said.

The snake was dubbed “Wessie” after Westbrook police officers saw it eating a beaver and swimming across the river in June. The snake was believed to be a python until the DNA tests were performed.

Wessie garnered national attention and a Twitter feed named “Wessie P. Thon.” It has more than 1,900 followers, including the Boston Globe, which tweeted Wednesday, “Should be fun to watch the swimming portion.”

The Cassidys said some of the triathletes had expressed concern about the presence of a giant snake in the river, but in the end the couple decided to hold the swimming portion of the race in the Presumpscot.

The city will station lifeguards on the riverbanks and have kayaks and paddleboards in the water to keep an eye out for Wessie. The swimming leg will vary depending on whether it is an amateur or professional race, with the longest distance set at 500 meters.

“Both professionals and amateurs will be joining Westbrook’s very own favorite anaconda, Wessie the snake, in the Presumpscot River for the swim,” Daniel Cassidy said in a media release promoting the event. “Athletes will then ride through downtown Westbrook and run along the river, finishing in Riverbank Park.”

Mike Lynch, 68, lives just over a mile from Riverbank Park and plans to participate in Saturday’s triathlon.

“I really don’t have a problem with swimming in the river,” Lynch said. “I don’t like snakes, no question about that, but I think a snake would flee if it saw a human. With 180 people in the water, Wessie will be going the other way.”

Placyk, the biologist, told Westbrook police in his report that anacondas’ primary defense against people is flight. “They will try and get away, usually via a body of water,” he said.

Event organizers are expecting 32 professional triathletes to participate, including 2016 Rio Olympians Ben Kanute and Sarah True. Kanute and True are members of the U.S. Triathlon Team. Major League Triathlon operates a league of eight teams, which competed in four triathlons during 2016. Westbrook is hosting the league’s last triathlon this year.

More than 150 amateur triathletes had signed up as of Wednesday, said Catherine Wilson, who is organizing the event for the city.

Wilson, the Westbrook Community Center recreation coordinator, said she worked with her son, Justin Irish, to design the Wessie T-shirt. Irish owns an online company called Epic Supply, Wilson said.

Westbrook City Administrator Jerre Bryant said Westbrook approved use of Riverbank Park for the event, but also offered an alternative swimming site – an outdoor swimming pool near the Sappi paper mill.

“I can guarantee that these athletes will never forget that they swam with Wessie,” Daniel Cassidy said.

The amateur races are scheduled to start at 7:30 a.m., with the pro race set to start at 11:30 a.m. National recording artist Russell Dickerson will perform a free concert in Riverbank Park after the race.