San Diego is launching a $10-million effort to complete risk assessments of all nine of the city’s aging dams — only three of which are considered in satisfactory condition. City officials say the assessments are expected to reveal problems that will require an estimated $1 billion in repairs and upgrades in coming decades — and possibly some replacement dams in extreme cases. San Diego’s dams are among the oldest in the state and the nation. State officials said three dams are in “poor” condition — Hodges, El Capitan and Lower Otay — and three have been rated “fair”: Morena, Barrett and Lake Murray.