Editing Hunua Ranges (section)

===20th century===

From the 1920s onwards the land was progressively bought by Auckland City Council utilising funds from its water supply operation.<ref name=barton1978>Barton, Ian L. 1978 ''"Auckland's south eastern bulwark : a history of the Hunua Ranges"''. Privately published.</ref> Development of the water supplies commenced in 1946, with the first of the four dams, Cossey's, completed with a capacity of 11.3 million cubic meters in 1956.<ref name="EvolvingAuckland2.1">{{Cite book| editor-first=John| editor-last=La Roche |title=Evolving Auckland: The City's Engineering Heritage |year=2011 |publisher=Wily Publications  |chapter=Auckland's Water Supply |first1=John |last1=La Roche |author-link1=John La Roche |pages=27–50 |isbn=9781927167038}}</ref> Three [[embankment dam]]s were constructed in the area: Upper Mangatāwhiri (1965), Wairoa (1975) and Mangatangi (1977).<ref name="EvolvingAuckland2.1"/> Combined, the dams have a capacity of  77.1 million cubic meters, and supply approximately 68% of Auckland's potable water, through the Ardmore Water Treatment Plant.<ref name="watercare">[http://www.watercare.co.nz/about-watercare/our-services/hunua-and-waitakere-dams-water/Pages/default.aspx] {{Webarchive|url=https://web.archive.org/web/20130210185519/https://www.watercare.co.nz/about-watercare/our-services/hunua-and-waitakere-dams-water/Pages/default.aspx|date=2013-02-10}}, Watercare Services Ltd. Retrieved 22 February 2013</ref>

A decision was made to reforest the ranges in the early 1960s, after the area had gradually reverted into farmland.{{sfn|Barton|2001|pp=85–86}} The bulk water supply operation and the land passed to the newly formed [[Auckland Regional Authority]] in 1964. The Authority completed the water supply development and continued the exotic afforestation on some of the north and western catchment land, started by the City Council, and its Water Department administered the land.<ref name=barton1978 /> The ranges were planted with a mix of exotic forest and native species, predominantly [[Dacrydium cupressinum|rimu]]. The forestry service nursery was one of the first organisations in New Zealand to propagate native trees through grafting techniques, and were the first to successfully graft [[Agathis australis|kauri]] trees. The forestry service was shut down in the late 1980s, as the Auckland Regional Authority was replaced with the [[Auckland Regional Council]].{{sfn|Barton|2001|pp=85–86}}

The water operation was corporatised as [[Watercare Services]] in 1992, but the land itself remained with the Auckland Regional Council. Watercare took ownership of the water related assets and took a long term lease from the Auckland Regional Council of the reservoir areas and the operational areas. The exotic forestry land was also leased to another party. The catchment land became regional park land.{{sfn|Barton|2001|pp=94–95}}