Source: Auckland Council
Auckland’s Manukau Harbour Te Maanukanuka-o-Hoturoa is well-loved and well-used by Aucklanders – so it’s important we continue to protect the health and vitality of the harbour.
In 2024, Auckland Council’s Planning, Environment and Parks Committee adopted strategic direction to achieve better environmental outcomes for the Manukau Harbour and endorsed a forward work programme.
Since then, staff have been progressing this programme, including the recent completion of an environmental assessment to identify priority focus areas to improve the health of the harbour.
Cr Richard Hills, Chair of the Policy and Planning Committee celebrates this small milestone and acknowledges the work needed to be done to ensure the council achieves the strategic direction adopted.
“We have a responsibility to look after our natural environment, including a significant statutory role to ensure natural environment outcomes for the coastal marine environment, such as harbours,” says Cr Hills.
“Decisions relating to policy and planning including land use zoning, environmental regulation, waste management, water services, and transport infrastructure, for example, all influence the state of the Manukau Harbour. Through this strategic direction, we can ensure that growth and infrastructure are delivered alongside prioritising the harbour’s health.”
Environmental assessment and prioritisation
This recently completed stage of the forward work programme involved an assessment of environmental state and pressures, a stocktake of the council’s environmental management activity related to the harbour, and the identification of gaps and priorities for further environmental management responses.
As a result, fifteen priority focus areas were identified based on the environmental assessment to help foster clean waters, thriving biodiversity, and climate resilience for the harbour.
These priorities range from reducing sediment from land-use activities, loss of coastal and marine ecosystems, to pressures on wading birds and seabirds using the harbour, to toxoplasmosis which threatens Māui dolphins of which there are approximately 54 remaining in coastal waters in and adjacent to the harbour entrance.
The health of the harbour
Some marine and coastal habitats are in good health while others are not. The sandflats in the main body of the harbour are considered in good health and support a diversity of life that provides food for the many wading birds that visit the harbour. However, historic loss of seagrass and saltmarsh habitat has not yet recovered, although some recovery in the amount of seagrass is occurring.
Additionally, sediment has been building up on the seafloor in the harbour’s inlets over a long period. This has reduced the diversity of benthic life (organism that live at the bottom of a water body) in the inlets, which has numerous flow-on impacts for life in the harbour.
“Manukau Harbour is recognised as a nationally and internationally significant bird habitat because of the numbers and diversity of bird species, as well as the high numbers of native and threatened bird species present. Wading and sea-birds face many pressures while in the harbour including habitat loss, pest animals, plastics, and disease,” says Dave Allen, Auckland Council Manager, Natural Environment Strategy.
Water quality
Most beaches around the Manukau Harbour are considered safe for swimming most of the time, referring to 24 of the 29 beaches assessed by Safeswim.
Monitoring of arsenic, mercury, copper, lead and organic contaminants has not found these contaminants at concerning levels in the harbour.
“Water quality is poor in the harbour’s inlets due to elevated sediment and nutrients coming into this system from the land. Water quality is poorest in and around Māngere Inlet. Algal blooms that would be expected with the levels of nutrients observed are not regularly occurring, because of the light limiting impact of the sediment in the water,” says Mr Allen.
Microplastics have been found at high levels in the sediments of Manukau Harbour beaches, compared with Kaipara and Waitematā harbour beaches.
Climate change is affecting the harbour, including increased sea surface temperatures, ocean acidification and rising sea levels. Climate impacts on marine species and habitats will increase over this century.
Next steps
The environmental assessment undertaken to date will underpin the next stage, which is to develop objectives to achieve the environmental outcomes and long-term vision that have been adopted for Manukau Harbour.
The council will continue to report and communicate on this work as it progresses. You can read the full report on KnowledgeAuckland: Manukau Harbour environmental assessment
Those interested in the future of the Manukau Harbour can also attend the Manukau Harbour Symposium – supported by the Manukau Harbour Forum. The Manukau Harbour Symposium will be held on Saturday 31 May in the Auditorium at Green Bay High School. Tickets are $15 each and can be booked through Evenfinda.
