The Queenstown Lakes District Council says it may be weeks before it has a conclusive result about what substance was poured into Horne Creek yesterday turning the water neon green.
In a statement, the council said there had been "a lot of speculation" about what the substance may have been, but said it was not associated with any council operations.
"The substance does have similar characteristics to water tracing dye, which is used for mapping waste and stormwater flows.
"This is not a toxic substance, but is certainly an unnecessary addition to an environment we work so hard to protect''.
CCTV footage showed the substance entering Horne Creek near the Queenstown library about 2.28pm yesterday.
The council was notified by numerous people at that stage and immediately dispatched a contractors' crew to the site.
"The water was clear in this location approximately ten minutes later as it moved down the creek and towards the lake."
The council was reviewing more CCTV footage and following up on "all possibilities regarding where the substance originated from".
"We don’t have any further information on that aspect, or what further action will be taken at this stage.
"We are taking the matter very seriously and would welcome any information which would allow us to identify the source of pollution."
An update would be provided when more information was available, the statement said.
"While we believe it may be tracer dye we are awaiting the outcome of testing being undertaken by QLDC to confirm this.
"While tracer dye is routinely used in stormwater networks the amount seen yesterday is far greater than we would normally expect to see."
The regional council used tracer dye "from time to time in carrying out our activities" however "we did not have any role in the substance being in the creek yesterday".
"We will await the outcome of the test results to identify the substance and continue to collaborate with QLDC staff to identify the potential source.
"Should we identify the responsible person or persons we will consider what if any enforcement action may be appropriate."
- additional reporting NZ Herald
