SACRAMENTO - A federal jury on Thursday found a 29-year-old environmental activist guilty of conspiring to burn down or blow up a northern California dam, a genetics lab, cell phone towers and other targets. Eric McDavid of Foresthill, Calif. faces up to 20 years in prison and a $250,000 fine for what FBI agents said was as an eco-terrorist plot in the name of the Earth Liberation Front, a shadowy, loose-knit group of environmentalists that has claimed credit for arsons throughout the West. McDavid and two others were arrested in January 2006 after purchasing bottles of bleach, a car battery,...