Although its 70 sq. miles make it the fifth largest lake in New Zealand, Lake Ellesmere, 20 miles south of Christchurch, has a maximum depth of only 7 ft. It is essentially a coastal lagoon separated from the sea by a gravel spit (Kaitorete Spit) that extends eastwards 18 miles from Taumutu to Birdlings Flat. This spit is formed of gravel from the eroding edge of the Canterbury Plain to the south, carried northeast by longshore drift. The Selwyn River flows into the lake from the north and has built a delta into it, but there is no permanent outlet to the sea. When the lake level rises sufficiently to endanger the adjoining farm land, an opening is bulldozed at Taumutu where the spit is narrow. The lake is brackish and abounds in flounders and eels; it also supports a large game-bird population, notably black swans and Canadian geese.

The Maori name for the lake is Waihora, said to mean “wide waters”. Lake Waihola, near Dunedin, was originally known as Waihora, for the same reason.

by Richard Patrick Suggate, M.A.(OXON.), D.SC.(N.Z.), F.R.S.N.Z., New Zealand Geological Survey, Christchurch.