If you are driving northwards from Christchurch to Picton, about 40 km (approx 25 miles) south of Blenheim you will suddenly come across a flash of pink or bright white (or both) on the landscape.
This is Lake Grassmere, a natural lagoon covering 17 square kilometers.
It’s right on the coast, separated only by a thin strip of beach, it has no natural inflow and is geographically in a location where strong warm winds predominate and rainfall is low.
The lake is also naturally shallow and has a high salinity, making it ideal for the production of sea salt.
Before salt production began here the lake was often muddy in winter and very dusty in summer and it was during the summer months that natural deposits of salt were found.
In 1943 this prompted salt production on a larger scale and in 2005 Lake Grassmere produced half of New Zealand’s domestic salt production.
However due to the demand for salt from industry (notably the pulp and paper mills and the freezing works) New Zealand still has to import half it’s salt requirements from Australia and the Caribbean.
The lake has been divided into seperate ponds suitable for solar evaporation, sea water is pumped in and moved between the ponds over several months and as evaporation takes place the salinity increases and crystalised salt forms.
The salt at the end of the production is white, but during the evaporation period algae (Dunaliella salina) living in the brine take on a red pigment known as haematochrome due to the high salt concentrations.
This phenomonon also accounts for why the highly salty Red Sea is so named.
As we drive past we can clearly see the agae’s hue from the road and then flashes of white of the salt piles.
I took the photos from the moving car so reflections in the glass window maar the view somewhat, the colours are more intense in real life.
I don’t know how often I have driven past here in my life… I’ve lost count, but it’s always been a place that intrieged me and it’s taken me until now to do some research and find out more.
I cetainly never realised that salt production here accounted for half of New Zealand’s domestic needs.
No doubt, many Kiwi’s like me have driven past it often, completely unaware of the significance of Grassmere’s small hive of industry because it sits almost in the middle of no-where but is actually an important player in it’s niche within the New Zealand economy.
… or maybe they do, but they take it with a pinch of salt.
Background information source: http://en.wikipedia.org/wiki/Lake_Grassmere