Investigations into the feasibility of a Branch River Power Scheme began in 1978, and following a detailed investigation in 1980, finance was approved with construction beginning soon afterwards.

Canal filling commenced in March 1983, with generation commencing at the Wairau Powerhouse in June, and at Argyle two months later.

A run of the river scheme with daily storage, the Wairau and Argyle Stations have one generator each, giving a combined output of 11 MW and an average annual output of 54.3 GWh.
                                                                                                     

Resource Consent applications seeking a re-permitting of the Branch Scheme were lodged in mid 1999. In early 2001, the Marlborough District Council renewed Resource Consents for the scheme for a term of 35 years.

Conditions within the new consents were developed through close and robust consultation, to recognise the desires of local fishermen and Fish and Game New Zealand. Consultation included how to consolidate the fishery within Lake Argyle, and enhance the fishery upstream of the Branch River intake by re-designing the existing fish pass.

A fishpass enabling trout to access the area upstream of the weir has been installed and commissioned, as has a separate pass for native species. In addition to this initiative, other methods of enhancing upstream stocking, including flow sharing and trout restocking, are being trialed in consultation with Fish and Game and expert advisers. While there has been mixed results with some of the trials, TrustPower will continue to work diligently to implement a satisfactory outcome for the fishery.

A Memorandum of Understanding has been entered into with tangata whenua to ensure there are ongoing efforts to improve the eel fishery. An elver trap has recently been commissioned as part of the drop structure at the end of the Wairau Tailrace, with the catch available for transfer to the catchment above the Branch Intake Weir or the wider catchment.