Maraetai I In early 1946, the Minister of Public Works
Bob Semple, announced a full development of the Waikato River, with the first three stations planned at
Ohakuri,
Whakamaru, and Maraetai. Although Ohakuri was chosen first, the choice soon shifted to Whakamaru as it would be the best location for transmission needs. However, more investigation had been done for the Maraetai site, and starting Whakamaru first would make it more complex to divert the river for Maraetai later, so it was decided to build Maraetai first. Investigations into a hydroelectric station at Maraetai had been completed between 1940 and 1945. The site was in a deep narrow
gorge, west of
Tokoroa and upstream of
Arapuni. Because of the narrowness of the gorge, the powerhouse took up the entire length of the base of the dam, meaning no orthodox
spillway could be constructed. This meant that the spillway had to be designed as part of the diversion tunnel. The site was composed of volcanic
ignimbrite, which had cracked extensively on cooling meaning extensive grouting of the rock was required. Construction of Maraetai I began in 1946, with the construction of an access road from Tokoroa, and establishing services and accommodation for the workers of the dam. The service and accommodation camp formed the town of
Mangakino, on the south shore of what would become
Lake Maraetai. Problems were encountered right from the beginning - the
Second World War had just ended, which meant there was a great deal of shortages of labour and materials. The Public Works department's work-force was less than two-thirds of its pre-war size, with thousands of vacancies not filled.
Concrete and
steel were also in short supply, as steel imports were less than half their pre-war levels, and local contractors could only produce two-thirds of the required amount of concrete. Combined with
industrial unrest and the nature of the site, the target completion date of 1951 became less achievable. ==Dam==