Lake Onslow

Lake Onslow
Location	Otago, South Island
Coordinates	45°33′S 169°37′E / 45.550°S 169.617°ECoordinates: 45°33′S 169°37′E / 45.550°S 169.617°E
Type	reservoir
Primary inflows	Teviot River
Primary outflows	Teviot River
Basin countries	New Zealand
Surface elevation	700 m

Lake Onslow is a man-made lake east of Roxburgh and south of Alexandra in the Otago region of New Zealand. It lies 700 m (2,300 ft) above sea level. It was formed in 1890 by the damming of the Teviot River and Dismal Swamp.

The lake is the subject of several paintings by the late Edward Mullor.