After seven years of investigations, the source of faecal contamination in one of the Bay of Plenty's most beautiful swimming spots is still hard to pin down.
In early 2015, Toi Te Ora Public Health issued a warning for people to avoid swimming at Kaiate Falls due to high levels of E. coli likely caused by faecal contamination.
Despite regular testing and work to find the source of the contamination, the health warning was renewed on Monday.
Environmental body Lawa (Land, Air, Water Aotearoa) regularly reports on the results of tests from 80 Bay of Plenty swimming spots. This summer it found nine, including Kaiate Falls, too unsafe to swim in due to poor water quality. Six of the 80 had no recent data to determine a finding.
Lawa - a partnership between regional councils, the Ministry for the Environment, the Cawthron Institute and Massey University - reports on water quality sampling results from each site, as well as overall bacterial risk based on longer-term testing.
A traffic light system identifies those sites suitable for swimming with a green light and those where caution is advised for young, elderly or people with compromised health with amber.
A red status warns the water is not suitable for swimming, either because the risk of infection or exposure to potentially toxic algae is too high.
As of yesterday, in the Western Bay area, Kaiate Falls, Uretara River at Henry Rd, and the Kopurererua Stream at McCord Ave have a red status.
In Rotorua, Utuhina Stream at Lake Rd, Ngongotaha Stream at Railway Bridge, Okawa Bay at Lake Rotoiti and Lake Rotoehu's Kennedy Bay and Ōtautī Bay have red status.
Caution is advised for anyone considering swimming at Waitui Reserve at Te Puna or Tilby Point Reserve at Matua as both locations have an amber status.
At Kaiate Falls, a stunning waterfall and swimming hole located in rural Welcome Bay, water samples found unsafe levels of faecal bacteria - again.
Chief medical officer of health Phil Shoemack said the falls have had problems for years.
"A lot of effort has been put in simply trying to find the source of the problem and there doesn't appear to be any particular point source such as concentration of animals or a broken sewer pipe - it just seems to be general run off which is a lot harder to fix than broken pipes."
People in contact with E. coli bacteria found in water bodies such as Kaiate Falls could experience gastro infections resulting in diarrhoea and vomiting, plus skin, eye and ear infections.
Shoemack anticipated there would be a higher risk to people's health from local waterways in general after the next heavy rain.
"We haven't had any heavy rain for a while ... but what it does mean is when you do get heavy rain ... all the contaminants that are sitting around will get washed into our lakes, rivers and streams," he said.
Bay of Plenty Regional Council acting general manager of integrated catchments Laverne Mason said Kaitate Falls fell into 11 "focus catchments" of priority and it had been working with landowners to "mitigate and remove the identified contaminants".
"It is an evolutionary process and one that understandably takes time," Mason said.
She said the issue with Kaiate Falls meant the waterway had been included in a national pilot study investigating the risk to human health from exposure to micro-organisms such as bacterial pathogens, campylobacter, salmonella, siga toxin-producing E. coli, protozoa giardia and cryptosporidium and human viruses: adenovirus, enterovirus, norovirus GI and GII.
The results of the study were unavailable as they were still being analysed but were expected to help provide greater understanding of the issue, she said.
Some of the council's work at the falls and Waitao catchment already has focused on creating large buffer zones around streams, tributaries and critical source areas "to reduce contaminants entering waterways".
"Since 2019 the catchment has had at least 51,800 native trees planted to date, 33 hectares of previously grazed riparian areas have been planted and/or retired and 11 kilometres of stream/tributaries excluded from stock. In the upcoming two years a further 57,000 native trees are scheduled to be planted, 10ha of land retired and 4km of fencing to be completed."
Mason said the 11 focus catchments had received "significant financial investment" but was unable to say exactly how much.
A Tauranga woman who swam at the falls on January 3 said she was not overly concerned about the health risk.
During her time at the falls, there were about 25 other people also going for a swim; "kids, old people, mums and dads".
The woman, who would not be named, said she was unaware of the health warning but saw the signs afterwards.
"All the people there, it made me feel less concerned that anything was actually going to happen. A lot of people seemed like they swam there regularly, a few of the people I was with were from out of town and seemed more concerned about it," she said.
"My friend told me the sign had been there for years and people swam there anyway."
Land use in the Kaiate sub-catchment area, about 800ha, consists of native forest (67 per cent) and pasture for sheep, cattle or deer (21 per cent).