July 28, 2008 - The Washington Nationals' new ballpark, which opened the season as the first major sports stadium to earn LEED certification from the U.S. Green Building Council, has drawn fire from environmentalists for its advertising relationship with ExxonMobil, the New York Times reports.

A giant Exxon logo looms large on the left-field wall of the ballpark and is often displayed on the scoreboard as well, prompting environmental activists to cry foul. Critics say the partnership overshadows the Nationals' sustainability efforts.

"ExxonMobil's involvement in the park burnishes the image of the worst environmental company on the planet," says Mike Tidwell, a leader of Strike Out Exxon, an activist group. "The more environmental the Nationals make that park seem, the stronger the payday for Exxon."

Exxon spokesman Alan Jeffers says the oil giant agreed to advertise with the Nationals as a means of highlighting its commitment to energy efficiency. "It's an interesting dilemma," says Jeffers. "We get criticized for not doing enough for the environment, then get criticized when we do" run an environmental campaign.

This could be a good warning for other teams planning to green more than just their turfs. U.S. teams including the Dallas Cowboys, Boston Red Sox, and St. Louis Rams have all staked a claim on greener operations in seasons to come.

Major League Baseball is in the midst of a green makeover, partnering with concessioner Aramark to boost recycling and use more recycled-content material.