Pest algae an issue at dam
A pest algae present across Canterbury’s lakes is causing problems at a South Canterbury dam set to be the subject of an important energy test later this month.
Lake snow, a plant with the consistency of thick green sludge, has been blamed for clogging up part of the infrastructure at the Tekapo A hydroelectric power station.
On Tuesday, Genesis Energy group manager corporate relations Emma-Kate Greer said the company had had been experiencing ‘‘more frequent blockages of screens’’ at the power station.
‘‘Testing has revealed high levels of the diatom ‘lake snow’ in some of the water diverted [through the dam].’’ Testing for the lindavia algae, commonly known as lake snow, earlier this year confirmed its presence in at least seven South Island lakes, including Tekapo, Benmore and Waitaki.
The plant was related to didymo, the nuisance pest that infected many South Island rivers. The algae was non-toxic and did not have any known health effects.
Greer said lake snow posed ‘‘no significant impact to our operations as Genesis undertakes regular screen clearing as required’’. ‘‘We notified the various agencies who have been looking into the presence of lake snow in the region,’’ she said.
Genesis’ teams remained ‘‘vigilant’’ about rigorously sticking to strict aquatic-biosecurity protocols, to prevent the pest plant spreading any further, Greer said.
‘‘Caring for our waterways is important so we’d encourage everyone with a boat or just enjoying New Zealand’s lakes and rivers to remember to ‘‘check, clean, dry’’.
Greer said Genesis remained ‘‘concerned about the presence of lake snow and will liaise with and support the various agencies exploring this issue’’. The dam was set to play a key role in the Tekapo area in the coming weeks, when a test of whether it could supply power to the surrounding area during a power outage would be tested.
Alpine Energy operations manager Rick Liew said Alpine Energy was carrying out routine maintenance on Tekapo’s connection to the national power grid on November 14 and 28.
Once work was completed during the second outage, before the town was reconnected, a theoretical alternative supply that could provide power if the town was cut off for real would be tested. ‘‘The Tekapo community has the benefit of having Tekapo A [hydroelectric] power station right on their doorstep.
‘‘It is possible that the power station could be used to restore supply when the main transmission network is unavailable for any reason. ‘‘Alpine, in collaboration with Transpower and Genesis Energy, the operator of Tekapo A power station, plan to utilise the outage to carry out a black start operation.
‘‘Black start is the process of restoring part of an electric grid to operation without relying on the external transmission network. In this case, the black start would be attempted using Tekapo A power station.’’