Ngai Tahu is losing faith the Crown will clean up of rivers and lakes

The South Island iwi has gone to the High Court at Christchurch to seek recognition of its sovereignty over freshwater.

Ngai Tuahuriri upoko Te Maire Tau says this isn't a claim of ownership - but recognition of the tribe's role in water legislation.

He says there's been a lack of political will - and a she'll be right attitude that has gone on for too long.

Tau says Ngai Tahu must be involved in regulating rivers and lakes for pollution and water take.