Take care near new monitoring equipment at Lake Benmore

Our scientists will gain a better understanding of the health of Lake Benmore - thanks to a new, purpose-built monitoring station.

The equipment includes a large yellow hull (about 1.5 metres wide) with a solar panel on top, six orange marker buoys, and underwater anchor ropes.

Lake users are urged to keep their distance from the gear, which sits in the Haldon Arm - north of Whanau Island, so important data can be gathered without interruption.

Changes in the water

Lake Benmore was artificially created in the 1960s by the construction of Benmore Dam and is now a popular boating, fishing and recreational spot.

In recent years the lake has seen changes in water quality, with increases in algal biomass (amounts of algae). Water clarity (measured as turbidity) has also changed. We have been continuing to monitor the lake and are also working with landowners in the area to reduce nutrient levels and encourage good management practices to help mitigate these changes.

Our surface water science team leader, Shirley Hayward, says the new monitoring set-up will complement the standard, high-country lakes water quality monitoring over summer.

"It will give us a year-round picture and better idea of how the lake is responding to pressures such as changes in land use, and changes in climate."

Find out more about the history of the lake.

Sensors provide real-time data

The monitoring station houses special sensors, which, instead of being fixed at one depth, travel from the top to the bottom of the lake several times a day - collecting data on turbidity, dissolved oxygen, temperature and algae.

Hayward says this provides a profile of the changes over depth.

"This is important in a lake like Benmore, where temperature and concentrations of algae, oxygen and water clarity can be quite different at the top and bottom of the lake."

The information is fed back to the science team in real-time and will help build a long-term record of water quality changes.

The findings will help inform future planning and research, and will be shared with the public.

'State of the art' monitoring

The recreational appeal of Lake Benmore means there is high public interest in any changes in its water quality.

A continuous lake profiling system is considered 'state of the art' in lake monitoring and will help measure the lake's response to changes in external pressures.

The station will be in place for at least five years, but it's hoped it will become part of our long-term monitoring network.

At the same time, work to reduce nutrient run-off from farming activity is continuing in the Lake Benmore/Ahuriri Catchment, with support from our land management advisors, the Upper Waitaki Water Zone Committee action plan projects and the community-led Ahuriri Catchment Collective.

Find out more about swimming water quality.