Te Rūnanganui o Ngāti Porou and the Gisborne District Council have agreed in principle to jointly manage natural resources in the region.
The trail blazing partnership allows the groups to share decision making for land and water in the Waiapu catchment.
Gisborne Mayor Meng Foon said in practice, that would mean joint hearings, committee membership, and collaboration in writing regional and district plans.
Rūnanganui chair Selwyn Parata said it was important because wai (fresh water) and whenua (land) are taonga (treasures) for whānau and hapū.
He said after 23 hui with whānau and hapū, the agreement was considered the most pragmatic and most effective means of giving effect to their rights and interest in wai in their rohe.
Mr Parata said it was a momentous occasion for the iwi and council to forge ahead together.
The agreement will be developed further before its adoption in October.