A campaign calling for cleaner lakes and rivers has been launched this summer, as monitoring data shows many spots across the country remain unsafe for a dip.
A newly-established group, backed by the Tourism Export Council, has launched a major petition demanding stronger Government legislation that would raise the minimum standard for freshwater.
So-called "bottom line" standards under the Government's National Policy Statement on Freshwater Management, set in 2014, included a requirement for regional councils to manage freshwater bodies so people's health was safeguarded when wading or boating.
But the group Choose Clean Water wants a tougher stance, ensuring waterways were suitable for swimming, and expects to collect 10,000 signatures for its petition by March.
According to the most recent Government stocktake, around two thirds of monitored sites were unsafe for recreational contact.
Another major Government report found water quality was worst in agricultural and urban areas where there was reduced water clarity and aquatic insect life, and higher levels of nutrients and harmful E.coli bacteria.
In Auckland, 54 per cent of the 100 or so streams and rivers it monitors are in a poor or degraded state - and summer monitoring data showed dozens of other regularly-checked sites elsewhere weren't safe.
Around Waikato, most monitored freshwater sites on the West Coast, Hauraki, Waipa River and lower Waikato River were "unsatisfactory", although quality was generally good in the upper Waikato River and in lakes and rivers around Taupo and Coromandel.
A number of sites in Northland showed consistently high contamination levels, such as Otiria Stream near Moerewa and Wairoa Stream in Ahipara, meaning they were not suitable for swimming at any time.
Other Northland swimming spots with current "caution" warnings included the Hatea River at Whangarei Falls and the Raumanga at Raumanga Valley Park.
Choose Clean Water spokesperson Marnie Prickett said her group would also be touring sites around the country this summer and making short films on the impact that polluted lakes and rivers were having on the lives of New Zealanders.
"Many of the people we are meeting with have seen what has been lost - their children no longer swim in the local river, it's harder and harder to find fish, and lakes have become so polluted they change colour with huge algal blooms and can't support wildlife."
Tourism Export Council president Martin Horgan said cleaning up waterways was important both for future generations and commercial reasons today.
"Our clean green image has worked as a marketing promise in the past, but if we don't do more to actively live up to it, in 50 to 100 years' time, there won't be anything to market."
Massey University ecologist Dr Mike Joy believed individuals and groups like Choose Clean Water could make a difference by speaking out and putting pressure on decision-makers.
The fresh call comes weeks after the Land and Water Forum issued the Government a raft of recommendations, including that farmers should have to exclude nearly all livestock from rivers and streams by 2025.
The Cawthron Foundation, also recently founded and headed by a former Parliamentary Commissioner for the Environment, has also made the issue one its priorities.
Check before going for dip
Aucklanders have been urged to check the latest monitoring data before heading to their favourite swimming spots this summer.
Monitoring results from Auckland Council showed nearly all checked coastal sites in the region were safe for swimming.
No-go zones included Piha South Lagoon and St Marys Bay, while Wairau Outlet and Coxs Bay had permanent health warnings.
"Water quality varies at different beaches and can change from day to day," Auckland Regional Public Health Service medical officer Dr Simon Baker said.
Meanwhile, data on the Land, Air, Water Aotearoa (LAWA) website showed a number of sites around the region marked as "caution" for their overall recreational risk levels.
They included Huia Beach, Titirangi Beach, Green Bay Beach, Laingholm Beach and Fosters Bay.