Wanaka gets much-needed stormwater study

Bullock Creek outlet into Lake Wanaka, the subject of two stormwater studies.

Two freshwater researchers will be studying the effects of urban stormwater run-off into Lake Wanaka starting this month. Funded through grants from Upper Clutha Lakes Trust (UCLT), ecologist Melanie Vermeulen and University of Otago masters student Victoria Grant will undertake testing and research to advance the understanding of stormwater quality across Wanaka’s urban development and understand the stormwater’s impacts and movement into Lake Wanaka.
The focus will surround Bullock Creek, a spring-fed creek that rises on Otago Fish and Game land and flows through town into Lake Wanaka’s Roys Bay. The research, a need that was identified in last year’s stormwater workshop held in Wanaka, will be used to better inform water management decisions to try and instill positive changes.

“Wanaka is growing incredibly quickly,” said UCLT Wanaka Water Project (WWP) manager Megan Williams. “Wherever you look there are new subdivisions and houses being built. The population is projected to double in as little as ten years. With rapid growth comes the inevitable pressures on our waterways. More earthworks, houses, cars and hard surfaces mean a major increase in stormwater runoff which can carry a host of contaminants. These can include: suspended sediment, heavy metals, animal faeces, pathogens, hydrocarbons (oil, tar and grease), garden fertilisers and weed killer, plastic, paints, dyes and sealants. The problem is, we don’t have a detailed record of what is going into our creeks, stormwater drains and eventually into lakes and rivers or any understanding of the impact of the contaminants which wind up in Lake Wanaka or the Clutha River.”

UCLT’s WWP provided grants to fund the research, which were secured from Central Government’s Freshwater Improvement Fund. The five-year WWP is also funded by Sargood Bequest, Million Metres, Queenstown Lakes District Council (QLDC) and Otago Regional Council; it is supported by Catchments Otago and Te Kākano Aotearoa Trust. Vermeulen’s research is also supported by Otago Fish and Game.

Two two research projects, which are expected to finish by the end of 2019, will analyse samples from streams and stormwater drains flowing through suburbs and developments into Lake Wanaka.  Both researchers will be testing for different factors, including habitat assessment and chemical analysis as well as urban runoff quantity and quality.

The results from both research projects will be presented to the Upper Clutha community.

In related news, to help offset the potential contaminant runoff into stormwater systems, QLDC offers residents an ability to opt out of their kerbside being sprayed if they would prefer herbicides to not be used near their house. QLDC has not disclosed which chemical they use for kerb spraying however they have said, “QLDC has undertaken trials of alternative sprays in the past, but they have proven both ineffective, expensive, or a mixture of both. QLDC’s Parks and Reserves team continues to look at market alternatives and keep up to date with developments here, and we would certainly consider the use of an organic product provided it proves to be effective on targeted species of plant, and cost-effective.” For more information on the No Spray Register, visit https://bit.ly/2vH7jTo.


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