This document transmits the U.S. Fish and Wildlife Service's biological opinion on the effects of the Bureau of Reclamation's proposed Pecos River dam operations from the date of this opinion (April 14, 2006) through summer 2006 (October 31, 2006) or until Reclamation implements a new operation defined in a Record of Decision, whichever occurs first, on the Pecos bluntnose shiner and its designated critical habitat and the interior least tern, in accordance with section 7 of the Endangered Species Act.