Protecting the Helena River (Mandoon Bilya)
Each autumn, the Helena River comes alive. Seasonal rains transform this exceptional waterway — flowing from the Mundaring State Forest through the Perth Hills before joining the Swan River near Guildford — into a thriving corridor of wildlife, water, and wonder.
For almost 40 years, Trillion Trees has been a custodian of this precious river, planting native trees, shrubs and sedges along its banks to restore water quality and shelter the wildlife that depends on it. Black cockatoos follow safe flying routes through the corridor. Snake-necked turtles swim its waters and nest along its banks. And the Mandoon Bilya holds deep cultural significance for the local Whadjuk people.
This river needs us now more than ever. In recent weeks, we've stood alongside the community to oppose a proposed large-scale data centre at the water's edge — a development that poses a serious pollution risk to the river and surrounding wetlands. The overwhelming community support has only strengthened our resolve.
In 2026, we're planting 6,500 native trees and plants along the Mandoon Bilya — and we need your help.
Every contribution makes a direct difference:
- $90 grows 30 native sedges, providing habitat for aquatic wildlife
- $150 builds quenda hotels, sheltering native bandicoots
- $400 funds nature care days, installing swales to slow water flow and protect riverbanks from erosion
Together, we can protect and restore this unique river corridor for generations to come.