Lost River Cave’s tour boat floated amidst a sea of billowy white clouds about 10 p.m. Wednesday – or at least, that’s what it looked like. The real culprit was soap suds, a recurring problem in the cave’s waterways, which lie at the lowest point in a 55-mile watershed.

The soap first appeared a week earlier, on July 20, and the situation continued to deteriorate until it reached Wednesday night’s peak, said Rho Lansden, Lost River Cave executive director.

While suds have a lengthy historical precedent in the cave after rainfall, Lansden said this time called for more concern. The suds appeared out of nowhere, without any precipitation precursor or other obvious cause.

“This has been happening over the years and it has usually been seen after rainfall,” Lansden said. “But according to my property manager, Justin Jennings, he’s observed probably since last November that we’ve been seeing on occasion soap suds without any significant rain, if at all, and that’s a new thing.”

As always, Lansden reported the suds to Matt Powell, Bowling Green public works environmental manager. Powell then reported the incident to Bruce Hatcher, Kentucky Division of Water environmental scientist, who came to test the water for turbidity and chlorine.

Turbidity measures the relative ability of light to shine through water without running into floating particles from silt, bacteria or other sources. Chlorine levels can also indicate the presence of harmful bacteria.

Hatcher did not test the water for optical brighteners, compounds often used in laundry detergents, or surfactants, chemicals that form bubbles around dirt to remove it from surfaces and are often found in cleaning products. He did not explain why, Lansden said.

“It seems like the state should be collecting samples and testing for surfactants and optical brighteners and what type of optical brightener it is,” Lansden said. “It looks like detergent, and I don’t know what else would make this amount of suds.”

Neither Powell nor Hatcher responded to requests for comment by deadline.

The suds impact more than cave visitors, “who have come from near and far” to see the cave only to be turned away while the suds clear away, and cave and watershed wildlife that seem unlikely to survive the influx of chemicals, Lansden said.

“My most worrying concern is for our drinking water,” she said.

Lost River Cave flows into Jennings Creek, which continues on to Barren River, the source of Bowling Green’s water supply.

Lansden is concerned that water quality will diminish as this problem worsens.

“We are going to get to the bottom of this. This has been an ongoing problem for years and it’s going to stop,” she said. “We’ve reported it often enough and we need a resolution. The community deserves answers.”

– Follow regional reporter Sarah Michels on Twitter @sarah_michels13 or visit bgdailynews.com.