One of Canterbury's most polluted lakes has become so toxic two organisations are banding together to improve it.
Lake Wairewa/Forsyth near Little River, Banks Peninsula, has been plagued with toxic algal blooms. The problem is now so severe, eeling has been banned.
Wairewa Runanga Chair Rei Simons said the ban meant Maori could not follow traditions they had practised for centuries.
The Christchurch City Council and the Runanga have agreed work together to improve the health of the lake by controlling water levels and sediments, which feed the problem.
Mayor Lianne Dalziel said the lake was "the life blood of this community".
"It is important that we work together to find solutions to the environmental hazards we are facing."
The Memorandum of Understanding outlines obligations from both parties to jointly manage the opening and closing of Lake Wairewa/Forsyth, erecting signage at the site, carrying out canal maintenance, and developing and implementing a landscape management plan.
The agreement will last for 35 years.