Maitai Valley Water Supply Scheme

Engineering Work (eg road, bridge, sawmill, dam)

The Maitai Valley Water Supply Scheme supplied 65% of Nelson City’s water in 1990, with a major emphasis in its design and construction on quality environmental and safety standards.

To provide an essential commodity, this scheme, opened in 1987, has paid particular attention to both safety and the environment.

The dam and water supply provide Nelson city and surroundings with an assured high quality water supply to meet its needs into the 21st century. Because of its proximity to the city it also provides a degree of flood mitigation and a recreational resource, while for the same reason its design has been particularly conservative including an analysis of the effect of a dam break due to unforeseen circumstances. The project is of national interest in its setting of high standards of safety and technical design for urban water supply.

The dam break analysis, by Dr. Alec Sutherland of Canterbury University School of Engineering, represented the state of the art in this specialist field.

The environmental evaluation and debate, and the resulting provisions for environmental enhancement and safeguards are unsurpassed in New Zealand for this type of project. It highlights the level of planning and public involvement needed to develop properly an environmentally sensitive project, and the need to budget for associated time and costs.

The intake facilities of the dam are of special design, and a key part of technical measures to avoid water treatment.

The project has also been noteworthy as a leading example to the engineering profession through its attention to safety aspects and use of detailed peer review of design and construction throughout the project. It is also noteworthy for the unusual solution to meeting the requirement of a judgement on the appeal against the water rights whereby the quantity of water abstracted by the intake on the adjacent tributary is replaced below the intake by water released from the dam in certain low flow conditions.

The project’s contribution to the region has been fundamentally beneficial in ensuring a reliable water supply to Nelson City and the surrounding area.

Designers: Tonkin & Taylor Ltd., Worseldine & Wells
Constructors: Wilkins & Davies Ltd., O.F. Howey Ltd

Heritage recognition

IPENZ “Engineering to 1990” project
This item of New Zealand’s engineering heritage was recognised as part of the IPENZ “Engineering to 1990” project which the Institution organised to help celebrate the country’s sesquicentenary in 1990. A plaque was unveiled to mark the significance of this water supply as part of the development of the nation.


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Maitai Valley, Nelson

Nelson Bays

Access Info
The Maitai Dam is part of the Nelson City Council's Dun Mountain Trail. (

Nature of Engineering
Infrastructure (incl. Road, water, ports), Natural Hazard Protection

Lat: -41.293318 Long: 173.370030