The Waimate District Council has lifted its "do not consume" water notice for more than 600 residents on the Lower Waihao (including Waikakahi East) rural water scheme.
Following months of observation, monitoring and ongoing tests, the council says recent results have now shown the water to be consistently within the acceptable MAV limits, meeting the drinking water standards and proving safe to consume.
Council’s asset group manager Dan Mitchell says despite the reduced nitrate levels, the existing water tanks will remain in place for the next few months – ensuring all residents continue to have access to safe drinking water in the event of another surge or spike in nitrates.
"It’s an important measure to ensure the tanks remain in place until final decisions are made around the operational arrangements and the commissioning of any solution," Mitchell said.
That's despite nitrate levels still being at a dangerously high level, according to Greenpeace.
Greenpeace held free water testing at Glenavy Hall last month, and it returned the highest nitrate readings for any town Greenpeace has conducted tests in.
Greenpeace has been undertaking free town-hall water testing since mid-2021 and also runs a free mail-in testing service, which has sampled over 1500 household bores.
Residents of the water schemes in the Waimate District have been drinking from tanks since August.
Their home water supplies were turned off after the nitrate levels exceeded 11.3mg/l, the maximum acceptable value under national drinking water standards.
Of the 59 samples tested last month, 86% returned levels over 1mg of nitrate per litre, which research shows starts to increase the risk of bowel cancer.
61% of samples taken returned a reading over 8mg per litre, which increases the risk of bowel cancer by 32%.
One sample came in at 12mg/L.
Residents want solution - soon
The Waimate District Council has proposed a denitrification plant, set to be commissioned in mid-2023, but most residents want a solution sooner.
Environment Canterbury says it continues to meet frequently and work closely with Waimate District Council, and it's providing technical advice to help inform the next steps relating to improving the water supply and designing the denitrification plant.
High levels of nitrate in the water supply are linked to intensive farming in the area.
ECan says its land management advisers are working directly with farmers offering free advice and support on best-practice farming to reduce environmental impacts, and, in this catchment, there is a strong focus on supporting the introduction of new nitrogen fertiliser rules, which further restrict the amount of synthetic nitrogen fertiliser that can be applied to pastoral land.
A targeted programme, focusing specifically on this catchment, is also being planned.
A public meeting was held last month with Greenpeace and Dr Tim Chambers from Otago University to address some concerns the residents have, particularly when it comes to potential health risks of high nitrate levels such as cancers, pre-term births and blue baby syndrome.
A community information session will be held at the Glenavy Hall on Wednesday, December 7 at 6.30pm, with Dan Mitchell encouraging all residents on the scheme to get along and learn more about the future options available.
"There are a few options on the table, and that’s something we need a steer on from the community. This will be a great opportunity to have any questions answered, discuss ongoing options around denitrification and talk through the supporting science in an attempt to reach a preferred solution," he said.
"Given that denitrification will have significant capital and operational costs, and the fact current advice is that the MAV remains at 50mg/l, the community will need to make a decision on the level of nitrate removal and how far council need to go with this."