SACRAMENTO — The son of a state senator billed water agencies and cities thousands of dollars last year for work that included writing speeches, organizing Senate hearings and arranging "photo opportunities" for his lawmaker mother. Tom Soto, president of the Santa Monica public relations firm PS Enterprises and son of state Sen. Nell Soto (D-Pomona), was hired by two San Bernardino County cities and two water districts in June 2002 after Sen. Soto established a task force to deal with groundwater contamination by the industrial solvent perchlorate. Since 1997, such contamination has forced the closure of 20 drinking water wells...