The swim portion of the Sunday run-bike-swim race was in jeopardy for weeks.
The Kentucky Division of Water lifted the advisory on Friday for the area of the river where the contest takes place. Other portions of the river are still under an advisory.
Karl Schmitt, president and CEO of the Louisville Sports Commission, says Ironman Louisville is largest Ironman competition in North America. It draws more than 3,000 athletes and has a roughly $5 million economic impact in the community.
A separate event, the Great Ohio River Swim, was cancelled because of the algae blooms.