Electric dinghy goes live at Wainono

The eels that live in Wainono Lagoon are not of the electric variety but the new dinghy that Environment Canterbury has certainly is.

The regional council has just launched its first electric-powered boat that will make water quality monitoring at the South Canterbury coastal lagoon quicker to undertake and safer for staff.

Up until now, an inflatable rowboat was used to get out to the existing monitoring site in the lagoon – which was a good exercise for the skipper but slow and challenging to work from.

When a new continuous water quality monitoring site was recently added 850 metres from shore, the team needed a vessel with a mode of propulsion and a stable base to carry out monthly sampling, calibration, and instrument readings.  Outside of these visits, the new water monitor continues to gather and report data and helps give Environment Canterbury a better understanding of water quality changes in the lagoon over short-time periods.

Evan Swale, from the Surface Water Science team, said the new boat was a great improvement on other designs and runs off two 55 Amp-hour batteries which can be recharged.

“Being electric is great for the environment and fits in with the lagoon and its status as a Department of Conservation Reserve.  The electric motor is very quiet which ensures minimal impact on the wildlife in the area.  It’s an aluminium pontoon with four chambers, so it’s also really stable to work from and handles small waves easily.”

The dinghy will be based in the Timaru office and, while mostly used for Wainono, will be available for other water monitoring activity in lakes and lagoons in the region.

Water monitoring at Wainono Lagoon

Evan explains that when visiting each of the two Wainono monitoring sites, he collects four different water samples in sterile bottles, which are then sent to a laboratory in Christchurch for analysis.

“The four samples are analysed for E.coli, nitrogen and phosphorus, water clarity, and one for chlorophyll A to check for algal growth in the lake.  We’ve also got a hand-held water meter which records water temperature, dissolved oxygen, conductivity and the pH - which all help build our understanding of water quality in the lagoon.”

Zone Manager, Chris Eccleston, says improving the water quality of the lagoon is a key aim for Lower Waitaki South Canterbury Coastal Water Zone.

“We now have new farming rules in place in this zone to reduce nutrient and sediment run-off into the waterways that flow into the lagoon, as well as Te Mana o te Wai Wainono Lagoon restoration project led by Te Runanga o Waihao. Improving water quality monitoring is key to tracking progress.”

The new continuous monitoring site measures a range of parameters that give a detailed picture of what’s happening with water quality in the lagoon: temperature, dissolved oxygen (important for many forms of aquatic life), conductivity (which measures conductive ions from dissolved salts and inorganic material, pH, turbidity (water clarity), chlorophyll A (responsible for photosynthesis), and blue green algae, as well as meteorological data like windspeed, solar radiation and rainfall.

The water quality probes are self-cleaning and the readings are checked against a separate meter during each monthly visit, with a calibration check carried out every three months.

Water monitoring at Wainono Lagoon is part of a network of hundreds of regularly monitored sites across Canterbury.  Water quality results are uploaded to the LAWA website annually and are used by Environment Canterbury to determine the state and trend of water quality in the lagoon.  It also helps determine if the management framework in place in the lagoon is meeting plan water quality objectives.  The trophic level index of the lake, an indicator of overall water quality, is calculated once a year using results from this sampling.

Wainono Lagoon - A significant area of biodiversity

The Wainono Lagoon is a 480-hectare coastal lagoon and wetland of national and international importance for its birdlife and native fish.  Its importance derives from the lagoon’s size, diversity of habitats and location in a chain of coastal wetlands.  The lagoon and its tributaries are highly significant to Waihao rūnanga as a mahinga kai source and a cultural site.

If you would like to read more about the Wainono Lagoon Te Mana o te Wai Restoration Project visit our Lower Waitaki South Coastal Canterbury Zone Biodiversity page.