[8] The amount of water that may be taken by the RDR scheme is governed by resource consents issued by Environment Canterbury to Rangitata Diversion Race Management Limited.

The operation and maintenance of the scheme requires RDRML to comply with a significant number of individual resource consents and their associated conditions.

The main resource consent (CRC182542) for the diversion of water from the Rangitata River was renewed on 14 August 2018 for a period of 24 years (expires 31 January 2042).

A separate resource consent (CRC011245) applies to the diversion of water from the South Branch of the Ashburton River/Hakatere – with a maximum continuous take of 7.1 cumecs.

[10] However, the main consent condition (CRC182542) limits the maximum combined take from the Rangitata and South Ashburton rivers to 35.4 cumecs.

The maximum volumes and rates of flow of water that may be taken from the Rangitata Diversion Race are specified in section 15 of the Irrigation Schemes Act 1990.

The power output available from the station reduced over a long period of time following commissioning, as a result of the gradual accumulation of sand in the canal.

This provided a trigger for Government to seek opportunities for public works that would get workers off the unemployment benefit and also raise farm productivity.

The planning and construction of the Rangitata Diversion Race was initiated and managed by the Public Works Department, with Thomas Beck as the lead irrigation engineer.

The original scheme included three waterfall drops at this point, each of about 2.4 m (8 feet), to maintain the standard gradient in the canal and prevent scouring.

[3] The RDR canal passes beneath the North and South branches of the Ashburton River in syphons constructed from large concrete pipe sections.

The recovery works following the slip required the construction of large concrete pipelines to carry the race in a syphon through the Surrey Hills.

[15] During a visit to the site on 19 October 1940 while construction was taking place, the Minister of Public Works, Bob Semple, had a photograph taken of his ministerial car inside one of the large pipe sections.

Approved in 1936 to provide unemployment relief and a vision for Canterbury's future, the 67 km race was the first major river diversion for the development of water resources.

[20][21] In September 2016, the Ashburton District Council published a Notice of application by RDRML for resource consents for a large water storage facility.

[23] However, the decision to grant the resource consents was appealed by several parties, including the New Zealand Salmon Anglers Association and Ngāi Tahu.

[24] In June 2019, while the disputed application for resource consents was still at the mediation stage in the Environment Court, the Minister of Conservation Eugenie Sage, announced that a project was being developed in conjunction with partners to enhance the ecological health and biodiversity of the Rangitata river.

[25] In July 2019, the New Zealand Salmon Anglers Association spokesman announced that they were withdrawing their appeal against the granting of consents for the extra 10 cumecs of water to be diverted at times of high river flows.

[26] In April 2020, New Zealand Salmon Anglers petitioned Environment Canterbury to enforce the Water Conservation Order on the Rangitata River.

The scheme includes 7 water storage ponds, holding a total of 16,500,000 m3 to distribute across 16,000 ha of formerly dry land farming area between the Rangitata and Orari rivers.