Geographical features: Selwyn District contains within it two distinct regions: the plains and the high country. The plains, where most of the population lives and the majority of activity takes place, form an expanse of low-lying, flat, and comparatively dry grassland. The extreme south-east is dominated by Lake Ellesmere / Te Waihora, an expanse of water surrounded by marshes, formed by the out-flow of the Selwyn River / Waikirikiri. The tributaries of the Selwyn River include the Waianiwaniwa River, the Hororata River and the Hawkins River.