Aspen evaluated impacts from construction and operation of two new substations, over 20 miles of overhead transmission line, approximately 2.7 miles of underground transmission line, and modifications to an existing substation. As part of the alternatives evaluation and screening process, 27 potential alternative routes or methods of providing the increase in electricity to the region were evaluated. The CPUC certified the EIR in May 2001, and construction began in September 2002. Aspen provided mitigation monitoring during construction.