The Maerewhenua District Water Resource Company (MDWRC) is a small community irrigation scheme with a command area around the Duntroon and Maerewhenua areas on the south bank of the Waitaki River.
The scheme was originally built by the Ministry of Works in the 1970s as a gravity-fed border-dyke irrigation system. It was sold by the Crown in 1990 to a collective of local irrigators who formed the MDWRC. The original scheme design used water from the Duntroon Springs and the Maerewhenua River, however the Waitaki River now provides a much higher level of reliability.
In early 2011, the scheme’s intake structure and headrace were completely destroyed during a period of sustained high river flows (around 1100 cumecs for three months). The scheme has therefore invested significantly in having the intake structure moved and rebuilt, and the headrace replaced with a piped reticulation system. A pumped extension has also been constructed to increase the area under irrigation whilst improving environmental flows into the Maerewhenua River.
5
pump stations
23km
of pipeline and races
$3.9M
estimated infrastructure value
Water is abstracted from the Waitaki River to the north-west of Duntroon and delivered to shareholders through a combination of pumped and gravity distribution systems. The intake structure comprises a rock barrier fish screen and a small settling pond, constructed off a protected river braid.
The intake pond discharges via an automated gate structure to a 1350 mm diameter concrete pipe. This pipe connects to an open race 700 m downstream. This open race delivers water a further 1800 m to a small balance pond and pump station near Duntroon.
From the balance pond, water is pumped alongside the Maerewhenua River towards Livingstone, and then further into the command area via series of booster stations. The pipe network comprises approximately 11.8 km of pressurised pipe which delivers water to on-farm holding tanks. Many MDWRC shareholders had previous water rights to irrigation supply from the Maerewhenua River which were rolled into MDWRC during a round of consent renewals.
Water is also moved underneath the Maerewhenua River via a piped siphon constructed of 900 mm concrete pipes. An earth lined open race then delivers water to shareholders along the SH83 road corridor. The race is approximately 10.9 km in length and terminates at Bortons Pond. The company is currently investigating opportunities to pipe all open race sections on the scheme.
Daily operation and maintenance of the scheme is managed under contract by Waitaki Irrigation Management Ltd (WIML).
The MDWRC is a limited liability company, operating under co-operative principles, whose purpose is to deliver water to its farming shareholders at the lowest possible long-term cost. The company has 15 shareholders, who farm along the Waitaki and Maerewhenua Rivers near Duntroon and who, collectively, hold 2024 shares (1 per irrigated hectare). Each share incurs an annual charge, payable to the company, which is used to meet the operating and debt-servicing obligations of the company.
The scheme supplies water for a variety of property types, needs, and uses including sheep, beef and dairy operations. Shareholders have signed a Water Supply Agreement (WSA) with MDWRC that contains binding obligations of share ownership.
Water is allocated on a per share basis at a maximum application rate of 500 L/s for border dyke and 0.5 L/s for spray irrigation. The annual volume of water allocated to each shareholder is stated in their farm environment plan (FEP), taking into account the number of shares that each shareholder owns. The annual allocation per share is derived from the scheme’s annual volume attached to the consent(s), taking into account “reasonable use” requirements.
MDWRC is administered by a board of directors comprising four farmer shareholders - Kelvin Weir (Chair), Russell Hurst, Michael Andrews, Grant Tremewan