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The U.S. National Whitewater Center acknowledges that algae in its artificial whitewater course weakened the effectiveness of its filters to disinfect waterborne illnesses, such as a brain-eating amoeba that was fatal to one visitor.

The center's response to questions submitted by The Charlotte Observer (http://bit.ly/29AUp0O) comes about one month after Ohio teenager Lauren Seitz contracted a brain-eating amoeba and died after rafting there.

Related: N.C. Whitewater Park Closes After Teen Dies

At the time, officials at the center said its disinfectant system was "99.99" percent effective against the organism.

Park spokesman Eric Osterhus said authorities are asking water quality experts how to contain algae that built up in the water channels. Osterhus said algae is generally not unsafe, but does create an environment that allows organic matter to grow and avoid the existing disinfection systems.