A Te Whakarewarewa Valley geyser that has been dormant for nearly 35 years has sprung into life in recent weeks, in what is being described as a possible world first.
The activity signifies the first regeneration of a Te Whakarewarewa Valley geyser since Rotorua's bore closure programme was implemented between 1986 and 1992.
Located near the world-famous Pohutu Geyser, Papakura was historically known as one of the highlights of a visit to Whakarewarewa Valley. Famous Te Arawa guide Maggie Papakura was named after the geyser.
Papakura had been a consistently active geyser until March 1979. The failure of Papakura geyser marked a turning point in the understanding of the damage that the bore use was having on springs and geysers.
The area has been hidden by vegetation for many years, but was uncovered by Te Puia/New Zealand Maori Arts and Crafts Institute staff last year.
In mid-September, bubbling water was sighted coming from the area and on Sunday, September 29, there was a series of small "eruptions", where steam and water were measured shooting up to 1m high.
GNS Science volcanologist Brad Scott said the geyser's reinvigoration was a significant development for the region's geothermal fields and was the first sign of renewed life in Te Whakarewarewa Valley since Rotorua's bore closure programme was implemented.
"Until Papakura became dormant in 1979, she was one of the most consistent geysers in the valley, only stopping once before during a significant drought in the 1930s.
As a result, when her activity ceased, it was a very clear signal that the area's geothermal resources were being depleted."
Mr Scott said the water temperature within Papakura had been rising steadily for some time, however the geyser's overflow was a significant milestone.
"It is a significant and reassuring development for the geothermal field," Mr Scott said.
Bay of Plenty Regional Council chief executive Mary-Anne Macleod said the revival of the Papakura Geyser might be a world first.
The regional council manages the field through the Rotorua Geothermal Plan, which constrains use of the resource to protect geothermal features.
"The revival of Papakura is great news not only for Rotorua, but for all those who have been involved over the years in monitoring and protecting these precious assets."
Council senior planner Bridget Robson said the Rotorua Geothermal Plan had tightly managed the resource and it appeared this action had something to do with the geyser's recovery.
"This could be the first time in the world a management response to a geothermal decline has had this type of result," Ms Robson said.
"Usually when geysers have stopped erupting, they have tended to stay that way. What's happening here suggests there is a big lag period between changing use patterns and the geothermal system responding. This will be of interest internationally."
The Rotorua Geothermal Plan came into effect in 1999, maintaining a 1.5km exclusion zone around Pohutu Geyser at Whakarewarewa, a zone established in 1986 to halt the progressive decline in surface geothermal activity. It saw the closure of hundreds of bores in the city.
After the closures, there were signs of a recovery in geysers, springs and other geothermal features.
Groundwater levels bounced back fairly quickly, Kuirau Park came back to life, Pohutu Geyser became more active again - but the recovery of other surface features was slower and Papakura, among other features, remained dormant.
The regional council became responsible for managing the geothermal field in 1991 and developed the Rotorua Geothermal Plan to protect the field and bring about recovery.
It sets out policies and rules for the use of geothermal energy, puts a cap on the amount of geothermal fluid and heat that can be used, promotes low-effect use and includes ongoing monitoring.
Te Puia chief executive Tim Cossar said Papakura's recent activity was an exciting development.
"Historically, Te Whakarewarewa's Maori culture and geothermal activity were real attractions for visitors to the valley, and the Papakura Geyser was one of the highlights.
"Today, Rotorua is still internationally renowned for its geothermal activity, with the Pohutu Geyser being one of the most photographed attractions in Rotorua."
Visitors to Te Puia are able to view Papakura from existing pathways.
Te Puia is on land leased from the Whakarewarewa Joint Trust. The land is jointly owned by Ngati Whakaue and Ngati Wahiao.
Whakarewarewa Joint Lands Trust chairman Malcolm Short said this was a remarkable recovery of a previous tourist icon in the Whakarewarewa thermal valley.
"It shows the cyclical nature of our geothermal field which is so dependent on groundwater levels. This has happened across our geothermal fields in the past and will happen again in the future."