Some of the local residents were retired scientists and were able to help with data collection to ensure Auckland Council's Safeswim could develop a more accurate water quality model.
Local board member Alan Cole lives nearby in Waiau Pa and said: "The key thing was that they [local residents] were able to do daily sampling and then they were able to prove what was happening."
Safeswim Programme Manager Nick Vigar says the removal of the long-term warning at Clarks Beach can be used as an example for other communities to follow.
"The work at Clarks Beach is a real success story of collaboration between the council and the local community – it's an excellent model of how a highly engaged community can work with the council to achieve great outcomes. Safeswim will be looking to use this model in other parts of the region as it helps creates a sense of understanding and ownership of local issues that is so important to resolving the issues."
Long-term public health warnings have been in place for nearly 20 years at some Manukau Harbour beaches, notably Weymouth Beach; historic monitoring has shown frequent exceeding of public health guidelines at several beaches.
Mayor Phil Goff said: "Swimming at our beaches is a cornerstone of the Kiwi summer. It's fantastic that we can tell Aucklanders that four beaches which have been no-go areas, some of them for nearly 20 years, are open for summer."
Meanwhile Waitākere Ranges Local Board Chair Greg Presland says Armour Bay is now considered low-risk for most of the time.
"Although there will still be high-risk periods occurring around some rainfall events, this will enable our community to fully utilise the beach and swim this summer without needing to worry about a risk to their health," he said.
"It's also a good reminder that Armour Bay property owners are generally not on the sewer town supply so it's important property owners are required to regularly check and maintain their on-site waste water systems."
The lifting of the no-swimming advisory is a result of better data collection, thanks to the council's Safeswim programme, which has enabled more accurate modelling. There may still be instances where Safeswim advises against swimming at these beaches because of localised issues brought about by rain and storms, or damage to infrastructure, so swimmers are advised to check at https://safeswim.org.nz/
Goff said: "Safeswim has provided us with the most precise and up-to-the-minute understanding of water quality in our city's history. It has helped us to target and tackle serious issues at our most-loved beaches, quickly and in a systematic manner.
"Improving the swimmability of our beaches won't happen overnight, but with the Water Quality Targeted Rate delivering $452 million investment in fixing water pollution, we are going to achieve in 10 years what would normally have taken us 30.
"It is remarkable that we can now remove the permanent public health warning that has plagued Weymouth Beach for nearly 20 years. It is recognition of the hard work of Auckland Council, Watercare and Manurewa Local Board to identify illegal wastewater connections, increase enforcement and fix damaged waste and storm water pipes."
Manurewa Local Board Chair Angela Dalton says the removal of the warning at Weymouth Beach is great news.
"We are delighted locals will finally be able to swim at Weymouth this summer without risking their health. The removal of the warning from Weymouth Beach after 18 years is particularly significant because it represents genuine improvement in water quality."