The mailer featured the face and endorsement of Gov. Jerry Brown on one side, a quote from a local business owner, and a photo of the wrong waterfront skyline on the other, with the words "Getting things done for Long Beach."
Lowenthal said she originally approved a nighttime photo of the Long Beach skyline for her campaign brochure and was "shocked" when she received the campaign piece in the mail.
"Everyone," Lowenthal said, "makes mistakes."
Mike Shimpock, Lowenthal's campaign manager, took full responsibility for the error and attributed it to a mixup with the printer.
Shimpock said he mistakenly flagged the photo, one of many stock images his firm had purchased for mailers throughout Southern California.
The error was caught, and Lowenthal approved a mailer featuring a photo of the Long Beach harbor at night, Shimpock said, but the wrong file was later sent to the printer.