Sustained rain in the catchment area has raised the level of Lake Hawea to nearly 346m above sea level, one of its highest levels in more than a year.
Contact Energy's Clyde dam generation manager, Graham Quinn, said from Christchurch that engineering staff were undertaking routine maintenance work at the earth Hawea dam structure.
Contractors were off-site by yesterday afternoon.
The maintenance work had nothing to do with the scoping work for the company's plans to build a two-turbine generator at the site, nor was it related to high lake levels, he said.
