"21 June 2005"

Takes form of letter.

Meridian Energy, which has a resource consent permitting the diversion of water from the Mararoa River into Lake Manapouri via the Waiau Arm, agreed to monitor for the microscopic presence/absence of didymo along the margins of the Waiau Arm and entrance to Lake Manapouri to validate previous reports that no macroscopic growths of didymo had been observed along the Waiau Arm, even though water had been diverted from the didymo-affected Mararoa River for several previous years when didymo was presumably present in the diversion water. The Waiau Arm Margin Surveys were conducted by NIWA five times from April to December 2005. The surveys showed that outside of the Manapouri Lake Control (MLC) area (zone 1) where didymo was expected to accumulate, there were no live or dead, microscopic or macroscopic didymo colonies along the river margins either in zone 2 (the main reach of the Waiau Arm) or in zone 3 (the Arm near the entrance to Lake Manapouri and along the Lake shore). Individual didymo cells, either dead or alive, were found extremely rarely along the margins in the main reach of the Waiua Arm (zone 2) and were not considered to indicate established colonies. (MAF Biosecurity New Zealand thanks Meridian Energy for funding these surveys.)

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