WAIAU RIVER, NORTH CANTERBURY
The Waiau River rises in the Spenser Mountains and flows eastward to the Pacific Ocean. The main tributaries in its 1,270-square-mile catchment are the Lewis River, which rises at Lewis Pass where the main highway from Canterbury to the West Coast crosses the main divide, the Doubtful River, which rises at Amuri Pass, the Hope River, which rises at Hope Pass, and the Hanmer, Mason, and Leader Rivers. The headwaters, up stream of the Waiau-Hope junction, were strongly glaciated during the Pleistocene. The straight east-west portion of the courses of the Hope, Waiau, and Hanmer Rivers lies along the Hope Fault, a major geological feature of the South Island. During an earthquake in 1888, fences across this fault at Glynnwye were broken and displaced 8 ft horizontally. This was the first conclusive evidence of horizontal fault movement observed in the world.
The Waiau River crosses the southern edge of the Hanmer Plain and then flows through a gorge to emerge on to the northern part of the Culverden Plains. It cuts through two more gorges before reaching the sea. The gorges have been investigated as possible sites for hydro-electric dams. The Waiau River was formerly called the Dillon or Waiau-ua, and was a major barrier to communication north from Canterbury until the construction of a bridge below the Hanmer River junction in 1864. The Lewis Pass highway provides easy access for deer stalkers to the headwaters of the river.
There is a Maori legend associated with this river and the Clarence. According to the story the Waiau-uha (Waiau) and the Waiau-toa (Clarence) were respectively male and female spirit lovers living in the Spenser Mountains. For some reason they were transformed into rivers, the sources of which were not far apart. When warm rains melted the snows and caused floods, it was said that the parted lovers were lamenting and that the rivers were swollen with their tears.
by Donald Rowe Gregg, M.SC., New Zealand Geological Survey, Christchurch.