Combine moldy stuffed animal, rice cooker scrapings, warped wall paneling, plastic bag and bureaucrat's cast-off office chair. Mix well. Spread evenly over layers of earth. Let stand 20 years.

Repeat this recipe in water several billion times over, as grizzled gangs of sanitation workers are doing in this odoriferous corner of Tokyo Bay, and you will get new land. Lots of it.

What the Japanese farcically call the Island of Dreams are actually two desolate islands each a mile long, rising high enough to afford one of the best views of the bay and consisting primarily of garbage. There was only water here before.

The land-poor Japanese have been waging a war of attrition against Tokyo Bay for more than five centuries now and these are their latest advances. Altogether, 85 square miles of the bay have been covered over, about 20 percent of its original area.

"In principle, I'm against what we have done. Nature should be preserved as nature," says Michifumi Ureshino, a Tokyo city planner who has worked on reclamation for 20 years. "But in Tokyo, it was inevitable, due to the dense population. We forced sacrifices on nature. Therefore, we have to view this land as a very precious thing."

Around Japan, people look to the sea when short of land. In Kobe, mountainsides were chopped away to expand port facilities. Osaka is preparing to build an offshore airport, lacking commercially viable space on existing land. The new land created totals 275 square miles.

There is no end in sight. In Tokyo Bay, in addition to the trash islands, mammoth works of conventional reclamation are under way at Tokyo's Haneda Airport and at the cities of Kawasaki and Yokohama to the south and Kisarazu across the bay.

Reclamation is said to have begun in 1457 when Edo Castle, today Tokyo's Imperial Palace, was founded, with earth from its moats being used to firm up nearby marshland. By the time Japan was opened to the West in the mid-19th century, the city's Nihombashi and Hibiya districts, now centers of financial and corporate decision-making, had been reclaimed.

From the start, reclamation was part calculated creation of new land, part helter-skelter disposal of trash. Besides ordinary refuse, mountains of rubble left by fires and earthquakes that periodically devastated the largely wood-and-paper city had to go somewhere. Much of it was carted straight to the bay.

Trash remains a problem in a city whose citizens habitually throw out things at the first sign of wear. The city generates 5,000 truckloads of it a day, plus quantities of sewage commensurate to a society known for being fastidious over personal cleanliness.

In daytime, the Island of Dreams, only five miles from the city center, is as busy as an expressway at rush hour. Convoys of blue garbage trucks roll up from a tunnel that links it to the mainland and, with split-second orchestration, upend their bins and speed back for more.

Much of the trash is burned first or fed into plants that chew it into small pieces. But these plants can never handle the supply and a good deal is dumped raw onto the heap. Fleets of bulldozers, their operators wearing masks against the stench, push it aside to make room for the next layer. At last count, the islands' peak was about 100 feet above sea level.

For future generations, the islands will be turned into parks. That is the only feasible use, as garbage-based land cannot bear anything much heavier than people.

Land that will bear factories and highways requires more solid materials, such as earth, gravel, sludge and ash from incineration plants. Tokyo has no shortage of these. Excavation for buildings and a new subway line under construction is now producing about 10,000 cubic yards of earth a day.

All of Tokyo port stands on custom-made real estate. Haneda Airport and Tokyo Disneyland do, too. New land has been created in the port for an oil terminal, a power plant, an apartment complex with 4,500 units, sewage treatment facilities and an industrial park.

On the bay's eastern and northern edge, in Chiba prefecture, the shore is lined with power plants, oil storage terminals, steel mills and smokestacks.

All of this has strained severely Tokyo Bay's environment. Last summer, 30,000 tons of shellfish were reported to have died off Chiba prefecture's shores. Environmentalists have said that in at least a third of the northern part of the bay, the water at the bottom has lost all its oxygen. They have estimated the cost of a thorough cleanup at $1 billion.

Environmentalists have proposed restricting shipping traffic through the bay and turning over much of the waterfront to recreation.

The trend, however, is toward further development. Officials and private companies are now looking seriously at building a combination bridge-tunnel to link the cities of Kawasaki and Kisarazu and span the bay for the first time.

Its cost would be about $4 billion. No one knows if or when ground-breaking will occur but next fiscal year the Ministry of Construction is expected to get about $30 million in its budget for preparation. In many eyes, that will be the starting gun.