Maitai Dam

Contents

Pre-dam schemes

The Maitai River was first considered for water supply in the 1930s. At this time the Brook Scheme (commissioned in 1867) was unable to meet demand.

Rather than proceed with the Maitai, the Government backed a weir on the Roding River, as this was seen to benefit not only the city (a much smaller place than today!) but also the Tahunanui Town Board, Stoke (then Waimea County) and Richmond Borough. The Roding succeeded for a time but by the 1950s more water was needed. A dam on the Maitai was proposed. The pipeline part of the scheme was completed in 1963 but the dam was postponed in favour of a temporary, intake grating on the South Branch.

Maitai Dam 1985Maitai Dam 1985. Nelson City Council.
Click image to enlarge
A dam at last

By the 1970s Nelson's water supply was suffering not only volume problems but also quality  problems. A Maitai dam was once again proposed, in 1973, but was heavily debated. The earth dam received scores of reports, financial and environmental assessments, public relations campaigns, letters to the editor, water right applications and appeals which dominated media and local politics for more than a decade.

Design for the new Maitai Water Supply Scheme was finalised during 1984, construction started later that year and the work was completed in 1987.

Maitai DameMaitai Dam 1996. Nelson City Council.
Click to enlarge
The Dam
  • Height: 36 metres
  • Length of crest: 140 metres
  • Width of base: 185 metres
  • Volume of Fill (Dam core) 272,000 cubic metres
  • Additional Fill (platform) 100,000 cubic metres
The Reservoir
  • Area 32 hectares
  • Volume 4 million cubic metres
  • Greatest depth 32.75 metres
Diversion Culvert

This culvert served as a diversion channel during construction (to enable the earth fill to be placed in dry conditions) and now holds the supply and scour pipes of the dam.

Maitai DamMaitai Dam 2005. Nelson City Council
Click image to enlarge
Intake Tower

Sits atop the valve chamber. The three pipes are each capable of taking 600 litres per second from the reservoir.

The Earthfill Dam

Piezometers were placed at 27 sites throughout the dam to measure seepage; flows from the various filter drains are also measured.

Concrete Spillway

Flow capacity of 125 cumecs (cubic metres per second) which corresponds to a 100 year flood event. Events larger than this will overflow to an unlined auxiliary spillway.

Cost in 1987 Dollars
  • Design and supervision           $1.8 million
  • Preliminary Works      $150, 000
  • Dam Works     $6.7 million
  • South Branch Works   $650, 000
  • Control & Instrumentation     $400,000
  • Total    $9.7 million

The Council received a subsidy from the Health Department of $1 million. The remainder of the cost was funded from loans which by 2005 were paid off.

Resource Consents
Maitai DamMaitai Dam observation tower. Nelson City Council
Click image to enlarge

Among the Resource Consent conditions are requirements that minimum flows in the Maitai River are 300 litres per second from April to October and 175 litres per second from November to March. In addition, any water drawn from the South Branch intake must be replaced with stored water from the reservoir.

Supply

Designed for peak demand 40,000 cubic metres per day. The Roding scheme contributes 13,000 cubic metres per day.

Nelson Water Treatment Plant

Opened in 2004 - supplies international standard water. Enables an additional 1 million cubic metres of previously unusable water from the Maitai Reservoir to be treated for supply. In 2005 supplies an average peak demand of around 42,000 cubic metres per day. Has the potential to treat 52,000 cubic metres per day.

This material is taken from the Nelson Heritage Trust Plaque at the Maitai Dam, 2000

Do you have a story about this subject? Find out how to add one here.

Comment on this story

Post your comment

Comments

No one has commented on this page yet.

RSS feed for comments on this page | RSS feed for all comments

Further sources - Maitai Dam

Books

Books

  • Cawthron Institute (1979) Environmental assessment of the Maitai Dam proposal, Nelson, N.Z.: author
  • Dams in New Zealand (1989) Wellington : New Zealand Society on Large Dams
    http://www.worldcat.org/oclc/23761133
  • Davis, S. (1982) Submission on the proposed Maitai water supply dam. Christchurch [N.Z.] :N.Z. Ministry of Agriculture and Fisheries
    http://www.worldcat.org/oclc/150742717
  • Nelson City Council (1987) Maitai water supply scheme. Nelson, NZ: author
  • Nelson City Council water supply augmentation : Maitai scheme feasibility study (1981) [Wellington : Tonkin & Taylor Ltd.]
    http://www.worldcat.org/oclc/233660846
  • Newell, J. (1982) Review of the Maitai Dam proposal : part of the Nelson City Council's water supply management programme. Thesis (M. Sc) University of Canterbury
  • Sutherland, A. (1980) Flooding effects from a failure of a proposed dam on the North branch of the Maitai river. Nelson, N.Z.: Nelson City Council
  • Wright, M. (2009) Big ideas :100 wonders of NZ engineering. Auckland, N.Z. :Random House
    http://www.worldcat.org/oclc/421587929

 

Articles

  • Council begins renewing dam consents (2002, May 4) Nelson Mail, p. 5
  • Costs, benefits in the Maitai's ebb and flow (2010, January 23) Nelson Mail, p.17
  • Day, M. (1982, October 4) Council counts cost to ratepayers of dam building delay, Nelson Evening Mail, p. 10
  • Day, M. (1982, October 6) City states its case for the dam, Nelson Evening Mail, p. 12
  • Day, M. (1982, October 7) Close look at safety angle, Nelson Evening Mail, p. 6
  • Day, M. (1982, October 11) Cheapest option, so it now - mayor.  Nelson Evening Mail, p. 10
  • The Maitai Dam (1987, May 27)  Nelson Evening Mail, [supplement]
  • Plan to dam Maitai criticised; Pollution `could reach pool area' (2005, April 9) Nelson Mail, p.3
  • Nichol, R. (1982, October 2) why south branch water is vital, Nelson Evening Mail, p.4
  • Nichol, R. (1982, October 2) What effects on Maitai if a dam is built. Nelson Evening Mail, p.4
  • Water demands (1999) Momentum : opus international, p.10

Web Resources