Calculating your environmental "footprint" online has become commonplace. Enter information about your home, car, commute and lifestyle, and with a click, you can tell how much your life affects the air, land and water.

The Chesapeake Bay Foundation soon will take that knowledge a step further, giving regional residents and businesses a way to essentially wipe away their footprints.

The soon-to-be-launched Chesapeake Fund will underwrite water-quality projects in targeted areas in the Chesapeake Bay watershed -- Maryland, Delaware, Pennsylvania, Virginia, New York, West Virginia and the District of Columbia.

The goal is to prove that the open market can be a solution to combating water pollution, making it cheap and easy to do so, and expand such projects to other regions around the globe.

The Bay Foundation recently launched the first step of the initiative, an online nitrogen calculator. Entering information about one's home, sewage system and auto usage delivers an estimate of how much nitrogen one produces in the watershed.

"It's not just agriculture that's polluting the bay, it's not just industry, it's really all of us," said Beth McGee, a senior scientist with the CBF.

For example, a three-person, single-family household on a one-acre lot with a $200-a-month electrical bill, hooked up to a conventional sewage system, which fertilizes its lawn two times a year, has less than half of the lot forested, and drives a late-model car about 20,000 miles a year will produce 13.64 pounds of nitrogen per year.

That's slightly less than the average 14.3 pounds per year, but far above the 8 pounds the CBF says households need to be producing to help clean up and restore the watershed.

Officials acknowledge the calculator is not a perfect tool. It excludes information about food -- how much meat or poultry we eat, and how far it travels to our tables -- but that will be included in a future edition of the calculator.

"It's starting to generate a bit of a buzz," said Dan Nees, who will manage the Chesapeake Fund, a partnership between the CBF, Forest Trends and the World Resources Institute. "We think we're on to something here."

Money from the offset credits will be spread throughout the region. The top-priority areas to be targeted include the Eastern Shore of Maryland, the Susquehanna River and the Shenandoah Valley, Nees said.

"You might be a business in Maryland [that purchases a nitrogen offset], but we might actually spend your dollars in Pennsylvania," McGee said.

One criticism of "carbon markets" designed to reduce greenhouse gas emissions has been that consumers don't know where the money is going, McGee said.

The Chesapeake Fund, by contrast, will be transparent, and take steps to monitor and verify its projects, she said.

The focus on small watershed areas within the larger Chesapeake watershed will help achieve that goal, she said.

"If we go into an area and hit a lot of landowners, and do a lot of good work, we will maximize our chances of being able to show a measurable reduction," McGee said.

Projects would focus on agricultural operations, such as forested buffers, cover crops and nutrient management techniques, McGee said.

For example, the Fund could work with farmers to reduce the nitrogen they apply, either by an incentive or by improving manure management techniques, she said.

The fund would not cover projects that are required by law, and would work within the framework of existing tributary strategies, McGee and Nees said.

"We'd be looking at what would be the most efficient way to make reductions," Nees said. "That would probably be, most of the time, agriculture."

Precise business-plan details of projects, guidelines and procedures are still being developed by the three groups, in concert with an advisory committee of environmentalists, financial experts and attorneys.

The fund is expected to be operating and financing projects by mid-2009, Nees said.

In the meantime, the nitrogen calculator is designed to improve awareness of individual impacts on the bay, McGee said.

"Hopefully the calculator will drive that home for people," she said. "It's incumbent on all of us to do what we can to reduce our pollution."

ON THE WEB

What's your "nitrogen footprint"?

Find out at http://cbf.org/yourbayfootprint.

Contact Dan Shortridge at 856-7373 or dshortridge@delawareonline.com.