Nueva Valencia is a third-class municipality in the province of Guimaras, Philippines. According to the 2015 census, it has a population of 39,810 people. Its territory includes the islands of Guiwanon (or Guiuanon), Panobolon, as well as numerous other minor islets. This is the site of the Guimaras oil spill in August 2006, when the oil tanker MT Solar 1 sank a few kilometers from Nueva Valencia. ^ Census of Population. "Region VI ". Total Population by Province, City, Municipality and Barangay.