At Woods Lake in Tasmania’s central highlands, we are managing water for power generation, ecology, irrigation and recreational fishing. It’s an excellent example of how multiple-use water management informed by science can deliver multiple wins.

Woods Lake

Multiple wins at Woods Lake

Until recently, the lake was suffering from a high level of turbidity (suspended particles) resulting in poor water quality. Combined with the poor state of the access road, this was limiting the appeal of Woods Lake for recreational fishing, despite its supply of trout.

Improvements in the lake’s ecology and upgrades to the access road have now transformed the lake into a popular fishery. The Inland Fisheries Service reported that Woods Lake was ranked third most popular angling lake in Tasmania in its 2016/17 survey.

While Woods Lake is popular for fishing, it also plays a part in our Trevallyn/Poatina hydropower system and provides irrigation water to downstream users. As well, it provides vital habitat for two threatened species of native fish, the saddled galaxias and the Arthurs paragalaxias. However, scientific surveys in the mid-1990s reported the decline and possible disappearance of the Arthurs paragalaxias from Woods Lake.

To explore the problem of high turbidity levels in Woods Lake, we commissioned a series of scientific studies. These revealed that there was a strong relationship between turbidity levels and the lake’s water levels.

We introduced management guidelines which kept lake levels higher than in the past. The aim was to reduce the frequency and severity of turbid episodes, with a long-term goal of reducing baseline turbidity.

To maintain the higher water levels and continue to supply irrigation water downstream, we occasionally needed to release water from Arthurs Lake to sustain Woods Lake. Although these management measures have not been without cost to Hydro Tasmania, they’ve proved their worth – and it is not only anglers who are benefiting.

Maintaining higher water levels has been very successful in reducing turbidity in Woods Lake. Reduced turbidity has improved water quality and contributed to a healthier lake ecosystem that can provide the necessary habitat to support threatened fish species.

The threatened Arthurs paragalaxias has now reestablished in Woods Lake. This is likely to be due to a combination of factors including translocations by the Inland Fisheries Service, immigration from Arthurs Lake during water releases to Woods Lake, and improvements in habitat quality due to improved management of water levels.