Source: Environment Canterbury Regional Council
The Banks Peninsula water zone committee recently dedicated $58,000 of their annual $75,000 Action Plan budget to Whakaora ai te wai o Te Pātaka – a collaborative approach to catchment management for Wairewa/Lake Forsyth, leading to the establishment of the new Wairewa Mahinga Kai catchment group.
Partnering together as mana whenua and neighbouring landowners, this community-led initiative is a great example of collaboration, focused on sustainable land use solutions, improving water quality, and restoring mahinga kai values.
A lake in need of rejuvenation
Te Roto o Wairewa/Lake Forsyth is a shallow coastal lake on the southwest of Banks Peninsula, regarded as a nationally significant wetland area that was once abundant with aquatic plant and animal life.
However, modern environmental pressures have led to a severe decline in the state of the lake.
Over the last 160 years, deforestation in this catchment has accelerated erosion and sediment loss, depositing an estimated 2 million cubic meters of sediment to the lake bottom.
“Te Roto o Wairewa/Lake Forsyth and the wider catchment is highly nutrient enriched, meaning the lake is in a poor state of health,” says Surface Water Science Manager, Elaine Moriarty.
“Water quality monitoring data from three sites around Te Roto o Wairewa/Lake Forsyth show high levels of phosphorus and nitrogen are present. These nutrients, in excess, act like pollutants causing regular algal blooms of toxic cyanobacteria that significantly impacting the lake’s ecosystem.”
Read more about the current state of Te Roto o Wairewa.
Ambitious plans to restore Wairewa
The catchment group has ambitious plans to be an exemplar restoration project for Aotearoa.
This mahi will build on the mahi of Wairewa Rūnanga to create a strategic catchment management plan that combines Mātauranga Māori and inter-generational landowner knowledge with the ecological and environmental sciences to better the catchment for future generations.
Building on the mahi of Rūnanga
Wairewa Rūnanga have already seen encouraging progress at Te Roto o Wairewa after investing in mahi to enhance the lake’s water quality. However, there is still a substantial amount of work to be done to rejuvenate the lake.
Improvements made thus far include significant works in the canal at the lake’s opening, as well as efforts to stabilise, reshape and revegetate the banks of the main tributaries. The intention behind these efforts has been to reduce the amount of phosphorus-rich sediment from flowing into the lake, therefore improving water quality and reducing the likelihood of flooding in Little River.
To build on the strides made by Rūnanga, the Wairewa Mahinga Kai Catchment Group aims to continue the restoration work by taking a catchment-wide approach – first creating detailed landscape models that identify key problem areas – then deploying targeted interventions like bank stabilisation works, riparian planting, fence installation, and pest control where they’re needed most. The catchment group also receives support from Wai Connection – Tatai Ki Te Wai and New Zealand Landcare Trust.
“As a committee, we’re excited to see a group of proactive landowners and Rūnanga coming together to create a holistic remediation strategy for the Wairewa catchment to restore our local waterways,” said Gina Waibl, Chair of the Banks Peninsula Water Zone Committee.
“We look forward to seeing this grant build on the legacy and gains previously achieved by Wairewa Rūnanga and support the group in their efforts to create a more collaborative management approach for the Wairewa catchment.”
Banks Peninsula water zone committee
The Banks Peninsula water zone committee is a joint committee of Christchurch City Council and us that works with the community to develop actions and tactics to deliver on the Canterbury Water Management Strategy. Water zone committees are made up of people with a wide range of interests in water who have a strong connection to the zone.
Each year, the committee makes recommendations to Environment Canterbury to allocate funding for projects that support the implementation of their Action Plan.
