No water is currently leaking from the dam, but it is rising by about 60cm each day.

A large slip between Wairoa and Gisborne has created a large and growing lake that presents a "significant hazard".

Hawke's Bay Civil Defence emergency management group was working with local authorities to monitor a growing dam of water and sediment sited on the boundary between Wairoa and Gisborne.

Hawke's Bay Civil Defence Group Manager Ian Macdonald said the large landslide had become a significant hazard and people are warned to stay away from it.

SUPPLIED The landslide has resulted in approximately 80 million tonnes of material forming a large dam on a small tributary to the Wairoa River.

"The landslide, likely triggered by a small localised earthquake earlier this month, has resulted in approximately 80 million tonnes of material forming a large dam on a small tributary to the Wairoa River. The new lake is about 50 metres deep and rising. The area affected by the landslide is 25.8 hectares and the landslide is still moving. No water is currently leaking from the dam, but it is rising by about 60cm each day,"

The landslide and dam are located on private property and in a remote area, but authorities want local people and downstream communities to be aware of the hazard risk. With the Wairoa District Council, Civil Defence staff have been talking directly with potentially affected residents.

"Downstream landowners and river users are strongly advised to keep out of the riverbed. The dam might fail at any time and there is a significant amount of water behind the landslide," he said.

He said the only structures threatened were a woolshed and shearers' quarters.

"We're working closely with Gisborne and Wairoa District Councils, with support from Hawke's Bay Regional Council to assess the risk of dam failure and develop an ongoing management plan," adds Mr Macdonald. Specialised engineers engaged by the Hawke's Bay Regional Council are due on the site today," he said.

Paparatu Road in the area is currently closed to the public and appropriate signage has been installed. There is no date for when the road will reopen at this stage.