Four local governmental entities have joined a whistle-blower legal action claiming the Los Angeles Department of Water and Power overbilled them by about $140 million since 1990, according to a lawsuit unsealed Monday. Accusations of false claims and other irregularities were made by the county of Los Angeles, the Los Angeles County Metropolitan Transportation Authority, the Los Angeles Unified School District and the Los Angeles Community College District. The action had been foreshadowed March 22, when Attorney General Bill Lockyer filed a separate legal claim alleging $60 million in DWP overbillings. The claimants are seeking damages that could cost...