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The history of Cloud Seeding in the Snowy Mountains

February 10th, 2013

The potential for cloud seeding in the Snowy Mountains was recognised more than 50 years ago, with the CSIRO conducting experiments in the region over the period 1955-59.

The outcomes of the research reported a 19% increase in snowfalls, however these were later were regarded as inconclusive because of perceived shortcomings in the design of the experiment.

Further studies to assess the potential for cloud seeding were undertaken in subsequent decades; however no cloud seeding experiments were undertaken.

An extended period of drought during the second half of the 1990’s prompted Snowy Hydro to further investigate and confirm the effectiveness of cloud seeding for enhancing snowfalls. During 2003, company representatives gave evidence to the House of Representatives Standing Committee on Agriculture, Fisheries and Forestry Inquiry into “Future water supplies for Australia’s rural industries and communities”, outlining a proposed cloud seeding research trial. The Committee subsequently found that cloud seeding should be considered as “…a potential generator of additional water”.

During the second half of 2003, a comprehensive review by an independent Expert Panel comprising 11 scientific experts concluded that cloud seeding over the Snowy Mountains region would be likely to increase snowfalls, and very unlikely to have an significant adverse environmental impacts or effects on rainfall downwind of the target area.

On 25 February 2004 the NSW Minister for Agriculture and Fisheries announced that after careful consideration of the Expert Panel Report, the NSW Government would make the necessary legislative arrangements for a six year cloud seeding trial to be undertaken. The Snowy Mountains Cloud Seeding Trial Act 2004 (NSW) (the “Act”) was subsequently proclaimed on 7 April 2004.

Amongst other things, the Act established the role of the NSW Natural Resources Commission (“NRC”) to “supervise authorised cloud seeding operations and report on the environmental impact of those operations to the relevant Ministers”.

In planning the project, Snowy Hydro consulted extensively with international and Australian scientists, and collaborated closely with local stakeholders to ensure the development of a robust experimental design and comprehensive environmental management plan (“EMP”) for the project. Under the EMP, environmental monitoring outcomes and operational data (for example, the times that cloud seeding experiments were undertaken, and the amount of cloud seeding agents used) were required to be reported to the NSW government every year of the trial.

The Snowy Precipitation Enhancement Research Project commenced in the winter of 2004, with all suitable storms seeded during this start-up year. All of the necessary infrastructure, instrumentation, experimental and operational procedures were developed and tested during the winter of 2004. Cloud seeding experiments commenced during the winter of 2005.

In late 2006, the outstanding scientific merit and national benefit potential of the trial was recognised by the Commonwealth government, and Snowy Hydro was awarded a grant of $4.02 million under the Renewable Energy Development Initiative to support the research.

With protracted drought conditions persisting in south eastern Australia, by late 2006 stakeholders commenced vigorous lobbying of the NSW government to increase the size of the cloud seeding target area, and to extend the duration of the trial. Interim results from the trial were found to be very promising, and comprehensive environmental monitoring undertaken since the commencement of the trial had shown no evidence of any adverse environmental impacts.  On this basis the NSW government passed amending legislation in May 2008, increasing the size of the target area to around 2000 square kilometres, and extending the duration of the trial until 2014.

By the early winter of 2009, sufficient cloud seeding experiments had been undertaken to allow for a robust independent scientific evaluation of the trial to be undertaken. That evaluation found cloud seeding increased precipitation by an average of 14%, and that there were no adverse impacts on rainfall downwind of the target area. Two separate, independent scientific peer reviews supported this result, with the research subsequently published in the peer-reviewed Journal of Applied Meteorology. It is interesting to note that the results are similar to those reported by the CSIRO study undertaken during the 1950’s.

The NRC also conducted its own independent peer review, consulting extensively with stakeholders and engaging further independent experts to assess both the outcomes of the experiment and environmental monitoring. The NRC review concluded the trial “…is of a high scientific standard and the evaluation plan is statistically sound” and “…we consider that overall there is acceptable evidence that cloud seeding has increased snowfall in the overall target area under defined weather and operating conditions”.

A separate comprehensive assessment of environmental monitoring found no evidence of any adverse environmental impacts associated with the cloud seeding trial. The NRC reported to government there is “…no evidence that cloud seeding operations have had adverse environmental impacts…”.

Snowy Hydro continued cloud seeding experiments from 2009, pending a decision by the NSW government on the future of cloud seeding in NSW. The exceptional scientific merit of the program and absence of adverse environmental impacts have been sufficiently compelling for the government to announce that it will now pass the necessary legislation for an ongoing, operational cloud seeding program to commence from the winter of 2013.

This means that cloud seeding over the Snowy Mountains will continue to bring significant benefits both locally and nationally well into the future.

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