By yesterday morning, 1809 people had been swab tested in Taranaki since last Friday and all 1557 results so far were negative.
But Taranaki DHB's medical officer of health Dr Jonathan Jarman said the wastewater results mean it is likely an infectious person was in the Stratford area since the start of the month.
"We are working on the assumption that the positive result was probably an infectious visitor or visitors to the region from an area where there is Covid-19.
"The alternative is we have undetected community transmission in Stratford, but this seems less likely."
He said continued testing of wastewater and people was the only way to know if there was widespread transmission in the region.
Recent weeks have seen travellers to Taranaki for garden festivals, and Jarman said garden hosts and other workers serving visitors must get tested if they have even mild symptoms.
Ngāti Ruanui and Ngāruahine both immediately began swab testing for Covid in Stratford on Friday – Ngāruahine have since been testing for six days, and Ngāti Ruanui for two.
Ngāruahine Iwi Health Services kaiwhakarite (manager) Warren Nicholls said he was happy with support from Taranaki District Health Board, which provided extra nurses essential for the testing effort.
But he said it felt like the iwi was doing more than just filling gaps in the public health response.
"We've stood up what we needed to, on behalf of the community, and if we need to do that again we'll consider that.
"But we don't want to be standing up to fill the gaps of other providers or organisations… Sometimes we need to lean on each other and that's okay but we don't want to make that the norm."
Nicholls said Ngāruahine didn't want to be duplicating other efforts and instead would be focusing on equity.
"We want to be targeting our most vulnerable, our Māori community, our whānau that have co-morbidities or who are reluctant to access the normal mainstream services."
He said a full diversity of people needed to be tested to be sure Covid was not in the community and the wastewater test results came from a visitor.
"We've had a higher proportion of Māori being tested in the last five days than non-Māori, that's a huge success.
"However, are there pockets of our community that we haven't reached yet? Is this sitting somewhere in the community unidentified?"
Nicholls said whānau now needed to get prepared for Covid, as an outbreak was inevitable some time soon.
Ngāti Ruanui response leader, Te Pāti Māori co-leader Debbie Ngarewa-Packer agreed whānau plans were urgently needed.
"We've had within 10 days two positive tests so it's very likely we have Covid around us. We need to understand the impact of that and what we all should be doing as a community.
"Whānau need to be talking about your plan, about your isolation space, do you have oximeters, do you have those who will come in and help you if you need kai?"
Ngarewa-Packer said it was vital to look after those responding to the pandemic.
"Those who are going to drop off kai, those who are going to do phone calls and check on the wellbeing of people, those who are going to be making sure we don't have what we see in Auckland: people sick alone and dying alone."
She said the scientific guidance offered by the medical officer of health had been excellent, but she was again critical of the DHB response.
"We've had excellent communication from Jonathan Jarman, but since it's come we've had nothing from the nurses, we've had no support offered from TDHB."
Ngarewa-Packer said it was time for the community, including businesses, to be extra vigilant.
"It's incumbent on us to be asking questions now."
"I think it's important we understand who is coming through our door and where they've been – including asking all sorts of questions you'd want to ask if someone was coming into your home."
Ngāruahine Iwi Health Services is pausing its testing today to vaccinate at Ngārongo Marae Ketemarae Pā on Mountain Rd from 9.30am to 2.30pm.
Nicholls says no booking is needed and all are welcome for a kōrero and kai, whether or not they decide to be vaccinated on the day.