The major development of water resources by dams in New Zealand has been planned for electric power generation and controlled directly by the Government on a national basis. The assessment of power potential from hydrological and topographical investigations and the planning and construction of the required dams and other hydraulic works is a function of the Ministry of Works (formerly the Public Works Department), and is performed on behalf of the New Zealand Electricity Department, the latter having responsibility for the power plant and its operation and for the transmission of power to distribution centres.

There are some instances of a limited contribution by hydro-electric works to facilities for land irrigation; for instance, economical electric power from the Roxburgh station enables the pumping of water from local sources, and in the Hawea Lake control works provision has been made to supply water to a future irrigation project. The influence of hydro-electric dams on ameliorating major flood effects in low-lying areas, though not neglected, is unlikely to be conspicuous because it lies outside their primary function.