The magic number at Eagle Lake this weekend is three.

The Gator Bait at Eagle Lake open water swim will celebrate its third anniversary on Saturday by adding, for the first time, a triathlon to the lineup. It’s Vicksburg’s first triathlon and is one of only two at Olympic distance — a 1,500-meter swim, 40-kilometer bike ride and 10-kilometer run — in Mississippi.

The triathlon will begin with the swim at Messina Landing at 7:30 a.m., followed by the bike and run along Mississippi 465. The open water swim will begin around 8:30 and includes races covering 400, 800 and 1,600 meters.

“A lot of people coming to the swim were bringing their bike or their shoes and doing that after the race. So we figured why not try this?” race director Matthew Mixon said. “It’s a great venue, and the sport of triathlon is really growing. There’s a great triathlon community here. Lots of us do it. I swim, some are bikers, others run. It keeps you from getting monotonous with your workouts.”

About 30 people participated in the first open water swim in 2009, and the number doubled last year. This year, it has dropped back to about 30, but Mixon said he’s happy with that. Most of the adults who had previously signed up for the swim are instead flocking to the triathlon, which has about 100 people registered.

The total number of roughly 125 is double what participated in the open water swim alone in 2010. There are triathlons and duathlons — races with two of the three events — nearly every weekend in Mississippi from March to November. For a first-year race on a crowded schedule, Mixon said organizers have been pleased with the response.

“We feel like 100 is a good number with people not having been here. A lot of these races have been going on for years and have a following,” Mixon said. “Everybody has been really pleased with the way things have been going. Everybody likes the venue. They think Vicksburg and they think hills, but it’s wide open out there. It should lead to some good times.”

Joe Giambrone, who is in charge of setting up the triathlon’s bike course and will race in the event, said Eagle Lake’s setting and facilities enhanced its appeal.

“We think it’s one of the best venues in the state, and we’ve been all over,” Giambrone said. “You have a great staging area. Some of these places, you’re out in a pasture. Here you’ve got a paved parking lot.”

Although the triathlon seems to have quickly surpassed the Gator Bait’s original open water swim in popularity, there are no plans to drop the swim from the lineup. Mixon said it remains popular with younger swimmers who aren’t ready to tackle the triathlon.

“Us being the swim team, we like to offer that to our guys that aren’t on the triathlon level yet,” said Mixon, who also coaches the Vicksburg Swim Association youth team. The Gator Bait races are used by the VSA as a fundraiser. “They really like that open water to see what all the time in the pool was for.”

The event itself is also growing. Besides the increased participation, the VSA has lined up River Region Health System as its first primary sponsor. Other companies have donated lesser amounts, and all will help the VSA improve and refine both the triathlon and open water swim in years to come, Mixon said.

“People don’t realize how much it takes to put on a race. It takes money,” Mixon said. “You have to pay for the timing, the T-shirts, the swim caps. It is essential for us to have sponsors to continue to put on a good race.”