The Intervale, the green floodplain where the Winooski River winds through Burlington, Vermont, was once the site of flourishing farms. Green Mountain Boy Ethan Allen had a homestead there, and long before him the Abenaki Indians cultivated the fertile soil. But as the city grew, the valley degenerated into a weedy urban wasteland, literally on the wrong side of the tracks. People still went there to fish, but also to dump garbage and old tires and cars. It wasn't a pretty or safe place to hang out; it was no community asset. The turnaround began with the McNeil wood-burning power plant. It was built at the entrance to the Intervale during the 1970s, when everyone was scrambling for energy that didn't come from the Middle East. Then Gardener's Supply, a gardening equipment store and mail-order house, settled nearby, because its founder, Will Raap, was attracted by the energy-saving idea of warming his building and greenhouses with the power plant's waste heat. Under Raap's leadership, and with the partnership of the city and the utility, that kind of thinking -- let's turn waste into resources -- has been moving steadily down the Intervale, turning it from a dump to a source of beauty, recreation, food and jobs.Now just past Gardener's Supply there is, appropriately, a garden. A seed company, The Cooks Garden, tests and demonstrates its special vegetable and herb varieties here. There are also plots for Gardener's Supply workers and a market garden that supplies a farm stand up at the entrance to the valley. A nature trail and a bike path take off from the gardens and wind along the river. On a sunny Saturday there are joggers, bikers, and families with baby carriages. The trails pass by a big field that grows organic produce for the kitchens of Fletcher-Allen Hospital, Burlington's main medical facility, not far away.A bit farther downriver is the regenerative engine of the Intervale, an urban composting project. The city's yard and food wastes come here, get mixed with milky wastewater from the Ben & Jerry's ice cream plant (the place smells of sour milk), and cook into mountains of fertilizer. This operation saves the county hundreds of thousands of dollars a year in landfill costs. The compost is sold to city gardeners and landscapers and plowed into the Intervale's fields to revive depleted farmland. Every few years the compost project is picked up and moved down the valley, leaving behind a fertilized clearing that forms the basis for a new farm.On the previous site of the compost operation is now a subscription farm, which sells shares to 350 families and 600 individuals, many of them nearby in the densely settled Old North End of Burlington. Member families pay a monthly or yearly fee and come by once a week to pick up a bag of freshly picked greens, beans, tomatoes, corn, potatoes -- whatever is in season. Further on there's a community garden where families work their own plots. Scattered within easy reach of the compost are other small farms, just getting going. The Stray Cat Farm grows cut flowers for sale at the farm stand and the Burlington Farmer's Market. Diggers Mirth is a collective producing veggies for families in the Old North End. Maxwell & Berry grow perennial flowers, Green Mountain Mesclun turns out tender baby salad leaves, and there's even, improbably, an artichoke farm. (I thought you had to live in California to grow artichokes, but here they are thriving.) The farmers starting out here are required to use organic methods and to draw up a careful business plan. In return they get cheap land rent, greenhouse space, shared equipment, and compost for a few years, until they get up and running.Gradually new space is opened for these ventures. Ben & Jerry's employees organize a work day, the city brings in trucks, and they clear out tires and garbage, plow the soil, spread it with compost, and plant cover crops, readying the soil for serious agriculture.Will Raap envisions moving right on down the Intervale, keeping natural vegetation along the river and in the wetlands and flood channels, but returning the rest of the land to a breadbasket that could supply as much as ten percent of Burlington's fresh produce. Raap is also still musing about that waste heat from the power plant, only a fraction of which is used in his own business. Some of it could heat "bio-domes," big greenhouses that could grow vegetables year-round. And he's picturing an "eco-industrial park" on nine acres next to the power plant. He's fascinated by the idea of waste from one industry becoming raw material for another. One of the first occupants of the eco-park will be Living Technologies, a company that designs and builds biological wastewater treatment plants that turn sewage into flowers, decorative plants, and fish. On a bright day, walking the Intervale with Will Raap, seeing what has already been accomplished, and hearing his dreams, I could picture clearly what is still to come. Up to $50 million a year in new economic value, says Raap, 150 more good jobs, in addition to the ones already created by the power plant, Gardener's Supply, and the existing farms. Everything running from renewable energy and recycled materials, using no toxics, turning out fresh, nutritious food for local consumption.A businessman walking with us caught the vision too and looked at Raap with awe. "Now there," he whispered to me, "is an entrepreneur!" (Donella H. Meadows is an adjunct professor of environmental studies at Dartmouth College.)