MAHA‘ULEPU — Results from a new kind of water quality testing show no imminent health threat for swimmers near the Waiopili Stream in Maha‘ulepu, and are casting questions on water testing methods that are being used in Hawaii.
It’s all contained in a report released Wednesday by the state Department of Health detailing a Lawrence Berkeley National Laboratory study of Kauai water samples using PhyloChip Source Tracking, which is a microbial source tracking tool.
PhyloChip is a DNA microarray that identifies more than 59,000 different types of bacteria in one sample, according to the study, and then provides a genetic fingerprint of the microbial community.
Scientists compare those genetic fingerprints with samples from places like injection wells, the mud in the streambeds, and animals in the surrounding areas to determine the source of the microbes.
Samples were taken throughout the Maha‘ulepu and Waikomo watersheds. In total, 13 locations were sampled in the Maha‘ulepu Valley, from the head of the valley through Warner Dam, and to the bridge to Makauwahi Cave.
Five locations were sampled along Waikomo Stream.
“While researchers were unable to pinpoint the exact sources of the bacteria, they conclusively determined human waste is not the cause of bacterial contamination in the water,” DOH said in a Wednesday release. “High bacteria counts historically observed in the Maha‘ulepu and Waikomo watersheds on Kauai are not associated with human waste.”
PhyloChip testing did, however, show that the water near Poipu Kapili Resort contained human feces in April and October 2018 testing.
Further research matched the microbes in the water with Poipu injection wells, however, DOH says it’s not enough of an indication to present a risk to swimmers in the area.
“(That location) was sampled at extremely low tide and took some time to collect due to a low volume of water at the site,” said DOH spokeswoman Anna Koethe.
For years there have been concerns about the high counts of enterococci bacteria in the Waiopili Stream and surrounding areas, a bacteria that indicates the presence of feces and pathogens in the water.
The PhyloChip study shows that bacteria aren’t coming from human waste. In scattered instances, the fecal indicator bacteria counts have come from cows and feral pigs, but the majority of the bacteria matched that in soil samples.
That indicates the high level of enterococci are naturally occurring in the environment and aren’t associated with pathogens that would be present if the enterococcus were coming from human or animal feces.
“Ninety percent of water samples exceeded the U.S. EPA recommended threshold for enterococci, yet only 25 percent had any fecal signal,” the report states.
David Burney, paleoecologist and independent scientist who has been working for years at Makauwahi Cave, said that’s because the soil in the tropics contains plethora bacteria that resemble fecal-indicating bacteria – cousins of the enterococci.
“What we’ve been picking up isn’t fecal bacteria. What we’re picking up are things that are giving a false positive from soils in tropical environments,” Burney said. “It’s a correlation, not the smoking pistol. It’s not the stuff that makes you sick.”
Unreliable testing, late report
The reason water testing on Kauai has been picking up those false positives, according to Burney and the DOH report, is that the Fecal Indicating Bacteria (FIB) tests being used were designed in temperate zones, not the tropics, where bacteria composition in the soil is different.
And it’s not only giving false positives, but also false negatives.
“It looks like results reported around Kauai may very well not only give a false impression of what places are dangerously polluted, but it looks like from this (Berkeley study) show the test can also fail to detect dangerous levels of fecal DNA,” Burney said.
Carl Berg, former head of Blue Water Task Force and current science adviser for the Kauai Surfrider Chapter, confirmed the traditional FIB testing isn’t always reliable.
“It does give false positives,” Berg said Wednesday. “(But), it’s the best thing we’ve got. EPA has been, for 10 years or more, trying to find another one that’s quick and correlated to human pathogens.”
He pointed out that, “when you get counts of 10,000 (enterococci) in Waipoli Stream, there’s a high probability that there are pathogens.”
DOH’s PhyloChip testing didn’t include pathogens, just testing for traditional fecal0-indicator bacteria like enterococci and Clostridium perfingens. Berg says they should have included pathogens in those tests to truly prove whether the water is safe for swimming.
“With the PhyloChip study, the question is whether or not it addressed if there were any pathogenic bacteria or viruses in the stream,” Berg said.
Meanwhile, some are concerned about the timing of the report’s release and question why it was released weeks after researchers were finished writing.
“How many versions of the report have they had?” asked Bridget Hammerquist, who has been working with Friends of Maha‘’ulepu to protect drinking water and the environment in the area. “We’re not sure what the department has done with the PhyloChip study initially released by Berkeley Labs, but we are concerned that there was a report which DOH asked the lab to change.”
DOH maintains the report wasn’t “in any way rewritten,” but that DOH did request clarifications and grammatical edits.
“After all comments and issues were addressed, the Berkeley Lab scientists produced the final report and provided the document to DOH as the final deliverable under the contract,” Koethe said.
Landowners and leaseholders in Maha‘ulepu are encouraged to hear that the testing showed the bacteria wasn’t from human waste.
“We want to thank the state for their time, energy and cost to complete the sanitary survey,” said Arryl Kaneshiro, general manager for landowner Grove Farm and chair of the County Council. “There were a lot of concerns about the quality of water in and around the Maha‘ulepu area. We hope this survey and the upcoming PhyloChip report will help quell any further misinformation about the area.”
Jessica Else, environment reporter, can be reached at 245-0452 or firstname.lastname@example.org.