Crotty Dam
| Company type | Dam |
|---|---|
| Industry | Hydroelectric power |
| Founded | 1991 |
| Headquarters | West Coast Range , Australia |
| Products | Hydroelectric power generation |
The Crotty Dam, originally referred to as the King Dam or King River Dam during its planning and approval stages, is a rockfill embankment dam featuring both controlled and uncontrolled spillways. It spans the King River nestled between Mount Jukes and Mount Huxley in Tasmania, Australia. This dam forms the reservoir known as Lake Burbury.
Built in 1991 under the King River Power Development Scheme by the Hydro Electric Commission, it enables hydroelectric power generation via the John Butters Power Station, located roughly downstream of the dam structure.
Features and location
Together with the Darwin Dam, Crotty Dam constitutes the primary water source for the King River Hydroelectric Power Development. Positioned within the upper King River gorge where the river traverses the West Coast Range, it captures substantial rainfall from the catchment area and channels water through a tunnel to the John Butters Power Station situated downstream.
The dam’s structure comprises of concrete-faced rockfill with a gravel core. The embankment reaches a height of and extends in length. When at maximum capacity, it stores of water. Lake Burbury spans and drains a catchment area of . Its single spillway, which includes both controlled and uncontrolled sections, is capable of discharging .
Spillway
A notable engineering aspect is the spillway’s placement on the embankment rather than on rock abutments—an unprecedented approach for dams of this scale due to concerns about embankment settlement. The embankment’s composition of well-graded gravels provides a high deformation modulus, thereby reducing settlement risks. The spillway incorporates an articulating design that can accommodate ground movement without sustaining damage.
This configuration allows sufficient time to activate a large jet flow valve within the diversion tunnel to safely handle extreme flood events. Engineers Sergio Giudici (who also served as chief engineer on the Gordon Dam), Frank Kinstler, Steven Li, Tony Morse, and Graeme Maher were honored for their innovative work on this articulating spillway system.
Power station
Water from Lake Burbury is transported through a unlined tunnel beneath Mount Jukes to reach the John Butters Power Station on the King River downstream near its junction with the Queen River.
History
Following the cancellation of the Gordon-below-Franklin power development scheme in the 1980s, construction of Crotty Dam commenced and was completed by 1991, finalizing the King River Power project by 1992.
The dam derives its name from James Crotty, who established the North Mount Lyell Copper Mine. The creation of Lake Burbury resulted in submerging the abandoned town of Crotty beneath its waters.
In the early 20th century, specifically during the 1910s, the Mount Lyell Mining & Railway Company explored nearby locations for potential hydroelectric projects. In 1927, Charles Whitham foresaw the eventual construction of such a dam and suggested "Lake Dorothy" as an appropriate reservoir name.
In 2001, Engineers Australia acknowledged Crotty Dam’s significance by including it among Australia's 25 dams with notable heritage importance and awarded it a Historic Engineering Marker through their Engineering Heritage Recognition Program.