The Tarwin River rises in the Strzelecki Ranges, a chain of hills running through the heart of South Gippsland. These ranges contain some of the most biologically significant vegetation in Victoria — cool temperate rainforest dominated by Myrtle Beech and Mountain Ash.
The upper Tarwin catchment is also home to the Strzelecki Koala, a genetically distinct population that depends on the quality of forest and riparian vegetation. Protecting and restoring forest cover in the Strzelecki Ranges is a long-term priority for Tarwin catchment health.