Before cloud seeding commenced in 2004, an 11 member independent scientific Expert Panel investigated the environmental issues associated with the proposed project. The panel concluded that cloud seeding would be unlikely to have a significant adverse impact on the environment. Nevertheless, environmental monitoring has always been a major part of Snowy Hydro’s Cloud Seeding Program.
The current cloud seeding Environmental Management Plan (EMP) was developed by Snowy Hydro in consultation with experts from the Office of Environment and Heritage (OEH), NSW Environment Protection Authority (EPA) and National Parks and Wildlife Service. The EMP applies to all cloud seeding operations and activities and specifies a range of controls in relation to:
Operations, including environmental controls relating to the establishment, operation, maintenance and decommissioning of all cloud seeding infrastructure.
Meteorological monitoring, including controls to make sure precipitation falls as snow to at least 1400 m during cloud seeding operations and to confirm no impact downwind of the target area.
Environmental monitoring, a program designed to detect any adverse environmental trend due to cloud seeding well before any level of concern may be reached.
A report documenting compliance with the governing legislation and EMP obligations is submitted to the NSW Government and the EPA each year for review. An operations report is published each year on the Snowy Hydro Cloud Seeding Program, following the EPA review.
Prior to the commencement of cloud seeding in 2004, background levels of silver in various matrices (soil, water, moss, peat, stream and lake sediment) were measured.
Around 7000 samples were collected between 2004 and 2014 to verify that there were no significant changes. The results have shown mean concentrations for all locations and sample types to be well below the relevant environmental guidelines.
Studies conducted in collaboration with OEH on aquatic macroinvertebrate populations in the cloud seeding target area and a similar untreated control area have also found no impact associated with cloud seeding.
In addition, a study is being carried out by the University of Queensland to investigate the long-term environmental fate of silver in the Snowy water catchment deposited from the atmosphere.
Silver is naturally present in the atmosphere, soil and sediments of the Snowy Mountains. This originates from natural weathering of rocks and from dust sourced from metal-containing landscapes upwind of the Snowy Mountains. Furthermore, metals released hundreds of kilometres away from sources such as fossil fuel combustion and metal production are transported through the atmosphere and deposited in the Snowy Mountains.
The current study is investigating silver released during cloud seeding operations within this context. It aims to better understand the distribution and movement of silver in the environment. Results from the completed study will be reported to the NSW Government and the EPA and research findings will be used by Snowy Hydro to inform the current environmental monitoring program.