The Democratic Party's main environmental enforcer, the Sierra Club, is having another revealing scrap over immigration. A year after losing in a rout, a group of anti-immigration insurgents is back this month making a run at five seats on the group's 15-member board. Sierrans for U.S. Population Stabilization wants the super-green club to endorse immigration limits, with a broader goal of freezing the American population. "The issue of escalating population growth in the United States is the single most important environmental issue in the nation," board member Paul Watson recently told the AP. In its wire-service deadpan, AP noted that...