The fascinating history of Windermere from ice age to global warming is told by leading scientist Professor Alan Pickering in his new book, Windermere: Restoring the Health of England's Largest Lake.

The former director of the Institute of Freshwater Ecology transports readers back in time over thousands of years to chart man's influence on Windermere and its catchment from the days of Stone Age axe factories and Roman forts through farming, mining, quarrying, smelting, tourism, fishing, boat traffic and pollution.

The story culminates with the threat to the rare Arctic charr population in the 1990s because of treated sewage which enriched the lake with nutrients, depleting the deep waters of oxygen.

Prof Pickering records the teamwork between scientists, environmental and water managers to devise a strategy to strip phosphorus from the treated sewage before it reached the lake, thus helping to preserve this rare fish, a relic of the lake's glacial history prized by scientists for its conservation value, by fishermen, and by gourmets as a local delicacy.

Prof Pickering told The Westmorland Gazette his book was aimed at "the interested lay person".

"In some ways it's one of the hardest things I've written because I had to keep stopping myself slipping into the jargon!" he explained.

"I would have thought most of the visitors that come to the Lake District would get something out of the book.

If you come to the Lake District you're coming for the environment, the landscape, the wildlife, whatever, because you're not coming for the sunshine or the ice-cream; so anybody with an interest in the natural world, I hope, will find it interesting."

The book has been produced for two reasons - to celebrate the 50th anniversary of the Lake District National Park, and to raise public awareness of a new partnership.

The Lake District Still Waters Partnership gathers together seven bodies with an interest in Windermere - the Centre for Ecology and Hydrology, the Freshwater Biological Association, the Environment Agency, United Utilities, the Lake District National Park Authority, English Nature and the National Trust - so that all their interests can be addressed when lake management issues are discussed.

In his book Prof Pickering describes the challenges facing the lake.

For example, the lake has got warmer in recent years, and the roach population has greatly increased, possibly because of the higher temperatures.

Scientists are not sure what impact that will have on the charr population.

Scientists are also trying to understand why reed beds are disappearing.

Prof Pickering strongly believes science can " really underpin" the way we look after the environment.

"The message is we do know a lot about what's going on out there.

If you're going to manage the environment, whether it's a lake or whatever, you have a better chance of doing that if you do it on scientific principles."

l Prof Pickering's book is on sale priced £10 at Ottakar's, in Kendal; Henry Roberts, in Kendal and Hawkshead; The Tinners Rabbit, in Ulverston; bookshops in Bowness and Ambleside; and on board Windermere Lake Cruises steamers.

It can also be ordered directly from: Department DWS, The Freshwater Biological Association, The Ferry House, Far Sawrey, Ambleside, LA22 0LP, tel 015394-42468, cheques payable to The Freshwater Biological Association.