It has been confirmed that Scotland's biggest hydro scheme in 50 years is unlikely to produce any electricity until 2011.

The £150million Glendoe scheme ground to a halt just two months after it opened following rock falls within its massive water tunnel.

In its half year results report, operator Scottish and Southern Energy admitted it is not expected to be operational again until the financial year 2011/12.

The statement is made in two paragraphs on page 18 of the 57 page report.

It reads: “In August 2009, SSE identified a blockage caused by a fall of rock near the top of the tunnel carrying water from the reservoir to the power station at the 100MW Glendoe hydro electric scheme.

Investigations have confirmed that the amount of debris is very substantial, but confined to a section near the top. SSE is now examining options in order to identify the best way to achieve a resumption of electricity generation at the site, including possible construction of a tunnel to by-pass the blockage, all of which will require a significant programme of work.

SSE now believes that the extent of the repairs required means it is very unlikely that any electricity will be generated at Glendoe until the financial year 2011/12. It also believes that a significant proportion of the financial consequences of the situation at Glendoe will be covered by contractual arrangements and insurance provision.

The site, at Fort Augustus near Loch Ness, was officially opened by the Queen in June.