On the Side: Campus cafeterias tray-free? Tres cool

Who would have thought it would fall to the 14-by-20-inch cafeteria tray to give us this season's lecture on the virtues of mindful eating, and the pitfalls, in a warming world, of profligacy, overindulgence, and wasting a third of a gallon of water per wash (not to mention a lot of food).

The Hummer. That you understand. A big, fat hog. Exhibit A on the enemies list of all things good and green. (And, blessedly, going out of production, a casualty of belated gas-mileage consciousness and, well, just plain consciousness.)

But it is the little guys who escape detection. At least in the short term: the polluting vehicles of another stripe - the ubiquitous disposable water bottle, the plastic shopping bag, the energy sucks that take their environmental toll not with a bang, but with the drip, drip, drip of a leaky faucet.

Let us turn, then, to the lesson of the tray, so anonymous and mild-mannered, stacked at the entry to the college dining hall: At the University of Florida, actually, they were found bound up in rope one day, with signs reporting how much water and energy was being saved by their non-use.

In a trial run at Harvard last year, about 22 percent less food waste was reported by going tray-less. (Other schools saw estimates of more than double that; juggling plates has its rewards.)

And most schools report saving thousands of gallons of water a month - talk about leaky faucets! - when there are no trays to wash.

The practice has spread with unusual speed, with food-service giants such as Aramark and student sustainability crusaders making rare common cause: Philadelphia-based Aramark sees fully half its 500 campus operations dumping their trays this year. (At the English House dining hall at Penn last week, Aramark's on-premises director, Tracey Hopkins, said he left 10 trays out as backups at first, then reduced it to five. Now only one is used, that one by a student with a disability.)

Sodexo district manager Bryan Sparks said the food contractor had removed trays at Rowan and Montclair State Universities, keeping them at Temple only because the dishwasher conveyor there needs to be reengineered to work without them.

It hasn't always been smooth sledding at first. At Vermont's Middlebury College, an early adapter in 2007, some students were "upset and pious" at first, said Matt Biette, the dining director.