South Island iwi Ngāi Tahu are taking the Crown to court over freshwater rights.
The iwi wants to tackle the ongoing degradation of awa and moana within its takiwā, or area.
And it is seeking recognition of its freshwater rights, responsibilities and obligations through a test case.
Papers have been filed in the High Court at Christchurch.
Claimant Te Maire Tau speaks to Corin Dann.