Pest al­gae an is­sue at dam

The Timaru Herald - - FRONT PAGE - BEN AU­LAKH

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.’’

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