Olympic marathon swim test run cancelled over water quality concerns for Seine River

A test run meant to allow Olympic athletes to familiarize themselves with the marathon swimming course in the Seine River was cancelled Tuesday over concerns about water quality in the Paris waterway.

World Aquatics made the decision to cancel the exercise at an early morning meeting, the organization said in a statement. Fluctuating bacteria levels in the long-polluted waterway have been a constant concern throughout the Games with the swimming portion of the triathlon and the marathon swimming events both planned in the river.

Another marathon swimming test event is scheduled for Wednesday, and organizers will decide early that morning whether it will go forward, the statement said. The women's marathon swim competition is set for Thursday, while the men are scheduled to race Friday.

The cancellation of Tuesday's marathon swimming test event comes a day after the triathlon mixed relay event was held in the river that runs through the center of the French capital. World Triathlon released data Tuesday showing that when the triathletes swam Monday, the levels of fecal bacteria E. coli and enterococci were within acceptable levels for the length of the triathlon relay course.

The swimming portion of the triathlon and the marathon swim both start and finish at the Pont Alexandre III, but the marathon swimming course extends farther down the river. Marathon swimmers do six laps on the 1.67-kilometer (1 mile) course for a total of 10 kilometers (6.2 miles.)

Water samples drawn early Monday showed E. coli levels ranging from "good" to "very good" at four collection points in the river, World Aquatics said.

It takes longer to cultivate enterococci samples, so the decision to cancel Tuesday's test run relied on samples taken