Approved at the Municipal Session of February 2, 1953, and declared Official by Municipal Decree No. 88 of February 1953, the emblem features:
A silver background, above which is a red bull, a symbol of the bravery of the ancient inhabitants of Laja Island. Above and below the central figure are three thick wavy lines representing the Laja (green) and Bío Bío (blue-blue) rivers. In the upper area of the silver field are six converging rays, in red, representing the strength of the spirit and the electrical energy produced in the area. Surrounding the silver field is a wide blue border, eight silver eagles, representing the Spanish and Chilean garrisons of the forts along the Bío Bío line.