CITY HALL — Santa Monica might be one of the most environmentally-conscious cities in the country, but the community’s own public transit agency was recently hit with a $21,000 fine for some eco-unfriendly practices.

The California Air Resources Board on Monday announced that it fined the Big Blue Bus for failing to test, measure and maintain records of smoke emissions from its diesel fleet in 2006 and 2007.

Agencies are required to submit reports annually.

The Big Blue Bus was also found to have violated the state’s fleet rule for transit agencies, which requires that entities keep diesel emissions no higher than 60 percent of 2005 levels.

The agency exceeded the threshold on Dec. 31, 2007.

A representative from the Big Blue Bus could not be reached for comment.

The fine will be divided into three parts — $15,768 for the California Air Pollution Control Fund, which finances research for improving air quality; $2,628 to the Peralta Community College to help support emission education classes; and $2,628 for the California Pollution Financing Authority, which provides loans to off-road vehicles that need to be retrofitted to comply with state standards.

Big Blue Bus staff members who are responsible for complying with state smoking test regulations will also be required to attend diesel education courses while bus drivers will be held to state regulations on engine idling.

The agency will also have to supply copies of smoke test inspection compliance records for 2008-11.

Karen Caesar, spokeswoman for the Air Resources Board, said that while the fine might seem surprising considering Santa Monica’s status as one of the greenest cities in the country, in reality many agencies do make mistakes.

She pointed to a list of groups that have been fined in the past several weeks, including Temecula Valley Unified School District, which was slapped with a $18,500 penalty for failing to inspect its diesel trucks; the Ventura County Transportation Commission, which will have to pay $5,000 for excess diesel emissions; and Tulare County Area Transit, which was hit with a $5,250 fine for air quality violations.

“If you’re someone who looks at Santa Monica as extremely progressive and a city that has gone above and beyond its duty to comply with environmental programs and developed its own environmental programs … then this would be surprising,” Caesar said. “In the real world, public entities slip up and this was just a slip up and hopefully it won’t happen again.”

melodyh@smdp.com