The Otway Ranges are an important water supply catchment, supplying water to 300,000 people in the region of Geelong, the Bellarine Peninsula, the Great Ocean Road, Colac, Warrnambool, and inland towns.

Forests enable water to be absorbed into the ground and gradually released, allowing a more even flow of water throughout the year than cleared land.

After a forest has been logged, the amount of water runoff in creeks and rivers decreases because more trees regrow than were there before logging. Trees act like pumps, pumping water from the ground and evaporating it from their leaves.

Fires in catchments have a devastating impact on water yield. Logging dries out the forest, increasing the risk of fire and associated water loss.

Logging and logging roads also affect the quality of water in creeks and rivers, and increase the risk of landslides.

Scientific research has shown that if logging in Geelong's water catchment stopped, water runoff would increase by 10% within 60 years. For Warrnambool's catchment (Arkins Creek), the increase would be 28%.

Logging in the Otways reduces the amount of water that is available to households and industry in the whole region.

In economic terms, the value of water is far greater than the value of timber and woodchips from logging.