Executive director Michael Brune would be the first Sierra Club leader to be arrested in an act of civil disobedience. The club's board of directors approved civil disobedience for the first time in its 120-year history as a way to oppose the pipeline, which would carry oil derived from tar sands in western Canada to refineries in Texas.
Activist Bill McKibben and actress Daryl Hannah also are participating in the protest.
Environmental groups want President Barack Obama to reject the pipeline, saying it would carry "dirty oil" that contributes to global warming.