Wellington Dam in the south of Western Australia near Collie is the largest water resource in the south west. Heavy rains have increased the dam level by 40% since July 2007. It is more than 96% of capacity. Every year the gate valve on the dam wall is opened, and 450 million litres of the most saline water is released into the ocean every day. When the process is complete, between 20 to 40 gigalitres of water will be lost. Even so, the dam is too saline for drinking water and barely suitable for irrigation.