The Stage 2 upgrade of Tasmania’s Murchison Dam has been completed, following 36 months of construction work, Entura has announced. The project involved raising the right spillway chute wall by up to 5m, requiring 1,600 m³ of concrete, 375 t of steel reinforcement, and the efforts of over 100 personnel.
Murchison Dam, part of Hydro Tasmania’s Pieman hydropower scheme, is 93m high and channels water through the Sophia Tunnel to Lake Mackintosh. The dam contributes approximately 25% of Tasmania’s renewable electricity generation.
Hydro Tasmania initiated a two-stage, $33 million dam safety upgrade program in 2019 to address increasing flood risks from extreme rainfall events. Stage 1, completed in 2020, raised the dam crest by 3m. Stage 2 focused on the right spillway chute, with construction of 14 concrete monoliths.
Entura provided specialist support across hydropower, dam safety, hydrology, hydraulic and geotechnical disciplines. Contributions included hydrologic and hydraulic modelling, dam break and consequence assessments, emergency planning, and independent design review.
The project faced logistical and safety challenges due to the remote location, steep topography, annual spill events, and high rainfall. Careful planning, lake level forecasting, and scheduling works for lower flood-risk periods allowed construction to proceed safely despite multiple live spillway events.
The completion of Stage 2 increases the dam’s flood capacity and reinforces its role in renewable generation, demonstrating Hydro Tasmania’s commitment to community safety and climate resilience. For Entura, the project reinforces its long-term expertise in dam safety management across the full project lifecycle.
