People in the hamlet of Santa Ursula began to worry when the logging started. In a few short weeks, more than a mile of densely forested riverbank was stripped from the Arroyo Sal to make way for heavy dredging equipment. Work was just beginning in late 2010 on an ambitious, three-year, $30 million project to build a 15-megawatt hydroelectric plant directly adjacent to the Cerro de Oro dam, with support from a U.S. government agency in Washington…