Forests are integral for water quality and quantity.
Forests play a key role in maintaining and improving water quality and quantity through a range of vital ecological processes. This is why VicForests carefully plans and manages our timber harvesting operations to protect water quality and quantity, rivers and waterways.
How VicForests protects water quality and quantity
VicForests carefully plans our harvesting operations to ensure important values such as waterways are protected. Protecting water quality is one of 6 core principles in the Code of Practice for Timber Production 2014 (the Code). We do this by applying evidence-based management practices, detailed in the Management Standards and Procedures for timber harvesting in Victoria’s State forests 2014 (MSPs), shown to be effective at minimising sediment and nutrient inputs to waterways.1
VicForests is permitted to harvest timber in a very small percentage of our catchment areas, under strict environmental guidelines monitored by the Department of Environment, Land, Water and Planning (DELWP). For example, of Melbourne Water’s 157 000 hectare catchment area, VicForests harvests an average around 210 hectares of forest a year, or just over 0.1%2 and only in the State forest areas that are jointly managed for water and some timber production.3
VicForests’ protection of waterways while harvesting involves:
Applying vegetation buffers alongside permanent waterways where harvesting activities are excluded to prevent ground and vegetation disturbance. This retains the natural filtration systems that trap sediment and stop it from entering waterways. The minimum buffer size is set by the Code and ranges from 20 to 100 metres. The size and type of buffer is determined by factors such as the classification of the waterway, its significance, slope, soil type and vegetation.
Minimising harvesting activities on steep slopes (more than 30 degree inclines). However, there are instances in which harvesting on steep slopes is permitted by the Code and the MSPs. In such instances any potential environmental impacts, such as potential impacts to water quality, are carefully managed and are done so in accordance with the rigorous regulatory requirements.
Applying vegetation filters alongside drainage lines and temporary waterways where machines are excluded to prevent ground disturbance.
Connecting the waterways and vegetation buffers to other protected areas where possible, which provides better habitat for wildlife and corridors to the forest outside of the harvest area until the harvested area regenerates.
Avoiding or minimising machine movement and other disturbance within or passing across waterways and vegetation buffers.
Scheduling operations in areas appropriate to the season and suspending operations when it is too wet to avoid soil compaction, erosion and sediment movement to help maintain water quality.
Carefully planning, building and maintaining roads to reduce the impacts of soil erosion and movement.
Many of Victoria’s water catchment areas are closed to any timber harvesting. Other catchments where timber harvesting is permitted are subject to seasonal closures where they are unavailable for harvest at times when risk of impact to water quality is at its highest. These closures are managed by the relevant water management authority and DELWP. There are also often limits on the area within water supply catchments that can be harvested annually or over a given time period.
There has also been significant research into the impact of timber harvesting on waterways. One study into water storage levels in Melbourne’s catchment found excluding timber harvesting in our catchments would result in a total increase of 1% in water yield over the next 40 years.4
In another study, the CSIRO5 found timber harvesting has significantly less potential and measured impacts on waterways than broadacre agriculture. Other independent research also concluded the best management practices employed in harvesting activities are effective at minimising sediment and nutrient inputs to waterways.
The impact of fire on water catchments
One of the biggest threats to Victoria’s water supply and quality are large bushfires.
An effective way to help prevent large, intense bushfires impacting drinking water quality is through fire prevention and management strategies.
VicForests and contractors work closely with Victorian government agencies to maintain fire prevention and suppression capability in Victoria’s water catchments.
This includes reducing high fuel levels through hazard reduction burning, building strategic fire breaks, and maintaining effective fire access through good quality road networks.
Victorians benefit from a sustainable and renewable native timber industry that protects biodiversity, traps carbon in wood products and the forests we regrow, and helps maintain the world’s best drinking water.
Swingler, K. (2006), “Impacts of timber harvesting on water quality in state forests supplying water to Melbourne”, SKM Consulting report prepared for the Victorian Department of Sustainability and Environment.
Averaged over a 10 period.
These areas became jointly managed when the demand for water from Melbourne’s expanding population could not be met by the closed catchments alone.
Feikema, P. et al. (2006), “Hydrological studies into the impact of timber harvesting on water yield in state forests supplying water to Melbourne – Part 1 of Hydrological studies”, eWater Cooperative Research Centre.
Neary, D.G. et al. (2011), “Water quality, biodiversity and codes of practice in relation to harvesting forestry plantations in streamside management zones”, CSIRO National Research Flagships Sustainable Agriculture Report.