The discovery of green algae in New Zealand's largest freshwater springs has sparked concern at the top of the south island.
But the Tasman District Council says there's nothing to fear.
Around 90,000 people visit the pristine waters of Te Waikoropupu Springs in Golden Bay each year.
It has 63 metres of visibility into its depths thanks to organisms which cleanse the water but the presence of algae is now threatening that clarity.
Kevin Moran has campaigned for the springs and surrounding aquifers to be protected from nitrate pollution.
He says he cried when algae was recently found.
"I was devastated, I was absolutely devastated," he told Newshub.
He believes it's due to increased nitrate levels - and has grave fears for the future of the cold water springs.
"This wonderland we have here will be lost."
But the Council says it's not unusual, especially at this time of year when it's warmer and lighter.
"Algae is everywhere there's water, essentially," said Rob Smith of Tasman District Council.
He disputes the link between this discovery and a slight rise in nitrate levels.
"We're talking about a fraction of very little and a change in a fraction of very little is hardly anything at all."
But the Council is taking samples to determine the species.
Meanwhile, campaigners like Kevin Moran are still awaiting a decision on a 2017 application for a Conservation Protection Order, to safeguard the springs.