Fisheye view

About this time every year, we would load up the family Volvo and head west over the rugged Welsh mountains to the tip of the Lleyn Peninsula - not to return until fall.

It seemed an endless journey along narrow mountain roads with their interminable zig-zag and dry-stone walling.

But I always anticipated one long stretch by the side of a lake. Underneath the gray waters, my father told us, were old stone cottages, their slate roofs submerged forever in the murky depths.

This was my Welsh Atlantis.

The lake appeared in the 1920s with the building of Trawsfynydd Dam. Valley and village were slowly engulfed by the rising waters that pushed against the dam wall and fed the hydroelectric power station.

I often wondered what that must have been like to see one's home bubble and disappear under mountains of water like some aquatic Pompeii.

Alexandra Ravinet's story at right takes more the fish's perspective on dam-building. She looks at new research into the ecological impact of harnessing a river's flow and how the river adjusts and restores itself when the barrier is finally removed.

The fish tend to fare badly in the first instance, but recover spectacularly in the second.

The coming decade may prove to be the fish's heyday. Thousands of dams, once the engines of industry across the United States, have long since become economically defunct as manufacturing companies moved away or closed down altogether.

The era of the dam-busters may have just arrived.

*Susan Llewelyn Leach is the assistant Ideas editor. Comments? Send e-mail to: Ideas@csps.com