LOUISVILLE, Ky. (WDRB) -- More than 2,000 people are scheduled to take part in the Ironman Louisville triathlon this weekend, but Mother Nature isn't cooperating, as there are still concerns about toxic algae blooms in the Ohio River. 

A total of 2,300 people are registered for the 13th annual race, representing 49 states and 29 countries.

The Sunday, Oct. 13 race will mark southern California resident Scott Tompkins' 15th full Ironman.

"It fills our soul. That's what it does for me," Tompkins said. 

New York native Jeannie Mahony says this weekend's race will mark her third Ironman. She told WDRB News she's looking forward to hitting the hills and seeing what she has for the run.

"You just have to accept what happens on the day," Mahony said. 

Experienced triathletes know plans could change depending on mother nature.

"There's always something. So whether it's extreme heat, or extreme cold," Tompkins said. 

This year that something could be the Ohio River. 

Last month the state issued an advisory on a toxic algae bloom in the Ohio River, where the swim portion of the race is completed.

Keats McGonigal, the senior regional director for Ironman, says officials are continuing to monitor the situation with the Kentucky Department of Water.

"We are testing that kind of on a daily basis and we are looking at it everyday," McGonigal said. "Right now the plan is to move forward with the whole event, but it's something we're watching." 

"I'd rather be safe, but you know if they let me swim in the green stuff I'm going to swim in in it," Tompkins said. 

If athletes are told the swim is cancelled at least they will still get to experience the Ohio, as this year's course will be less through downtown and more along the river.

"You can't control everything. You can control your attitude and your effort and being grateful for having the opportunity to be here," Mahony said. 

Participants from 18 to 77 years old will start bright and early at 7:30 Sunday morning, with a 2.4 mile swim in the Ohio River, followed by a 112-mile bike ride through Oldham and Henry Counties. Competitors then run a full marathon to round out the over 140-mile race. 

Officials say a big change for this year will be the run route, which will stay closer to the river instead of running through downtown.

Road closures will start as early as 5 a.m. Sunday, with some roads remaining closed until 1:30 Monday morning. Some of the main streets affected include portions of River Road, Witherspoon, and Second Street. Dozens of other roads in Louisville La Grange, Goshen and Pendleton will also be closed for parts of the day during the race. 

Click here for a full list of closures. 

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