The Blanket Effect is intended for others to learn about weather modification and its related subjects in an easy to understand way. Started in 2005, this blog is a work in progress as the technology advances

January 15, 2007

Status Report on Snowy Mountain Program

Research Project Annual Report
Published: October 2005

The Snowy Precipitation Enhancement Research Project (SPERP)
and its monitoring program were established to answer to following questions:

-Will cloud seeding increase snowfall in the Snowy Mountains?

-Will cloud seeding have a significant adverse environmental impact?

In February 2005, Snowy Hydro Limited (Snowy Hydro) submitted the first annual report on its cloud seeding trial to the NSW Government.

The report covers the calendar year 2004, in which Snowy Hydro established and tested its cloud seeding equipment, and developed and tested the protocols it intends to use to monitor the effectiveness of its cloud seeding operations and their environmental impacts.

In March, the Minister for the Environment referred to this annual report to the Natural Resources Commission (NRC) for review and provision of advice on the progress of the trial, its environmental impact to date, and the validity of its environmental monitoring elements.

The NRC has now completed this review. It analysed and assessed the information provided in the annual report, and consulted with Snowy Hydro and the Department of Environment and obtained additional expert opinion from the Commonwealth Scientific and Industrial Research Organisation (CSIRO). This report presents and explains the NRC's findings and recommendations.


The Snowy Mountains Cloud Seeding Trial Act 2004 authorises Snowy Hydro to conduct cloud seeding operations in the Snowy Mountains subject to certain conditions.

Snowy Hyrdro's annual report indicates that they are conducting the cloud seeding trial and associated environmental monitoring in accordance with the Act and their environmental management plan.


Snowy Hydro is generally using the best available technology and procedures, some of which are well established and others are 'cutting edge'.

They are using innovative approaches to overcome some inherant limitations in the design of the trial.

However, the NRC believes the trial may have difficulty establishing statistically whether cloud seeding operations are increasing snowfall, as the planned trial duration (5 years) is quite short for a trial of this type, and as the trial has insufficient controls by which to judge the relative impact of cloud seeding and natural variability in snowfall.

Snowy Hydro has developed an experimental design that includes randomised cloud seeding over a target area to assess the impact of cloud seeding on snowfall.

This technique relies on replication in time rather than in space to statistically demonstrate the impact of cloud seeding.

The longer the trial runs, the greater would be the chance to reliably demonstrate if cloud seeding has increased snowfall.

To be sure of delivering a reliable result, the trial may need to be extended to around 10 years and to have a conventional control area added which is biophysically comparable to the target area.

A decision on whether or not the trial may need to be extended can be deferred until say year 4 by which time the adequacy of the data acquired to that point should be evident.

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