A £10m management plan for the World Heritage site at Fountains Abbey and Studley Royal was launched on Tuesday.

The plan will ensure that the site is protected for future generations. It identifies maintenance and conservation work and endorses the commitment between the National Trust and English Heritage to the 18th century "green" garden at Studley Royal.

The garden, which survives substantially in its original form, is said to be the most spectacular water garden in England.

Fiona Reynolds, National Trust director general, and Carole Souter, acting chief executive, English Heritage, launched the plan which will be implemented over the next 30 years.

Both organisations have worked successfully in partnership for 14 years at Fountains Abbey and Studley Royal since the estate was designated a World Heritage site.

After a tour of the gardens and monuments it was launched at the Temple of Piety, where both speakers were the first to sign the visitors book.

Mrs Souter said: "England leads the way in the production of World Heritage site management plans. We are all feeling our way in an exciting new world - a world which recognises there are some places on our small planet that are so special that they deserve the utmost care.

"What is a World Heritage Site? Well, most of you will think of the Taj Mahal or Hadrian's Wall, but in England we also now have 13 sites ranging from the prehistoric Stonehenge to the modern industrial village of Saltaire, Bradford.

But Studley Royal and the ruins of Fountains Abbey is the only World Heritage site designated for its 18th century landscaped gardens and associated medieval remains. Landscape does not come any better than this."

She added: "I encourage all of us to keep on developing the close working relationship which will lead to the site becoming even more serene, and a united oasis in our increasingly noisy and divided world. We all need this special place, let's work to keep it special."

The management plan:

l sets out the vistas for Fountains Abbey and Studley Royal;

l explains what is so special about the site;

l identifies key management issues;

l outlines the detailed six-year objectives and action plan.

In her speech Ms Reynolds expressed pleasure to be marking the culmination of two-and-a-half years work preparing the plan.

"This is an opportunity to celebrate after a very difficult year in 2001 due to foot-and-mouth disease which had a major impact at Fountains as at so many properties last year. It lost £400,000 as a result of the disease.

Mike Brooksbank, the Trust's property manager took the VIP guests on a tour of the site and explained that the Trust and English Heritage had a very delicate balancing act to complete.

"We work to try and preserve the site, yet make it attractive and accessible to visitors. This creates tension in what we do and try to achieve.

Today isn't about the abbey, the reason most people visit, but our primary aim is the gardens which are largely untouched."

Fountains Abbey and Studley Royal gardens were created between 1718 and 1781 by John and William Aislabie. It is the National Trust's most visited pay-for-entry property. As one of the major tourist destinations in the North of England it makes a significant contribution to the local and regional economy.