Wyangala Dam

Facts and History

Wyangala Dam is situated on the junction of the Lachlan and Abercrombie rivers about 48 kilometres upstream from Cowra in Central West NSW. The dam is about 320 kilometres west of Sydney.

Wyangala Dam’s storage capacity of 1,217,000 megalitres is more than twice the volume of Sydney Harbour.

The dam is named after Wyangala Station, one of the properties on which it was built.

Why the dam was built

By the early 1900s it was clear that further development of the Lachlan Valley required a dam to regulate variable river flows. Following completion of NSW’s first dam for irrigation – Burrinjuck on the Murrumbidgee River – worked started in 1928 on the state’s second major irrigation dam, Wyangala on the Lachlan River.

When completed in 1935, Wyangala was designed to irrigate 15,000 hectares along the upper reaches of the Lachlan River, supply water to people and stock over an area of half a million hectares and open up a quarter of a million hectares west of Eubalong for settle and development as wheat farms.

Today the dam provides water for a far larger area following the dam’s enlargement in 1971 and fourfold increase in storage capacity. Pasture and lucerne now have the largest combined irrigated area, followed by cereals and other crops such as oilseeds and legumes. The dam also irrigates cotton around Hillston and smaller areas of vineyards around Cowra.

How the dam was built

Construction of Wyangala Dam began in 1928 and finished in 1935. Hundreds of workers lived on-site at Wyangala township in cottages and barracks. They used steam engines and manual labour to build the wall, with a railway line transporting materials to the site.

The original structure at Wyangala was a mass concrete gravity dam 58.8 metres high with a storage capacity of 374,860 megalitres and a surface area of 25.2 square kilometres.

The dam was later enlarged with a rock-fill embankment with a clay core built downstream of the original concrete wall. Enlargement work began in 1961 and finished in 1971. A new spillway capable of withstanding a very severe flood was built, along with a road bridge over the spillway and new low level and high level outlets.

Raising the crest 23.5 metres increased the storage capacity by almost four times to 1,220,000 megalitres with a lake surface area of 53.9 square kilometres. The rock-fill embankment also strengthened the structure to meet modern dam safety standards. The original concrete dam wall can be seen when the water level falls below 30 percent.

Later improvements

To meet modern dam safety standards and increase dam safety in the event of extreme flooding, in 2009 the walls of the downstream spillway chute were raised. Work is currently underway to install a gate raising and locking system so the dam’s radial gates can be raised and locked open in the very rare likelihood of an extreme flood. A new bridge was built downstream of the dam wall as part of the upgrade for vehicle access across the river.