The Greater Wellington Regional Council has admitted it failed to properly consult Wairarapa iwi before spraying a popular patch of watercress.
A drain that runs alongside Manaia Road southeast of Masterton where the watercress grows was treated with herbicides by council contractors.
Local iwi, Kahungunu ki Wairarapa, became upset because many local whānau pick watercress from the site.
Council regional environment group manager, Nigel Corry, said the drain was sprayed as part of its flood protection strategy and it has been treated before.
But he conceded it could have done better and talked with iwi first.
"What we take on board, very clearly, is that maybe our engagement with iwi prior to the spraying this time around wasn't adequate enough", said Mr Corry.
"And it may well be that we could do a lot better on that front. So we take that on board and very much are happy to work more closely with them".
Mr Corry said the council would be identifying important mahinga kai (traditional Maori food gathering) sites by working more closely with the Mana Whenua in the rohe.
"The council's had a really strong relationship with iwi throughout the region over many number of years in looking at significant sites, particularly looking at the value of mahinga kai.
"We've reflected that in our regional policy statement, the concept of mahinga kai is well understood and is being developed in partnership with iwi.
"If there are sites that we don't have an understanding of, or even if it's not a significant site that we're aware of, we are completely open to working with iwi around that."
Mr Corry said in future, the council would make more of an effort to erect warning signs when it sprays herbicides on waterways that may be mahinga kai sites.
He said the council is happy to listen to Kahungunu ki Wairarapa's concerns.