Research on embankment dam monitoring was recently carried out at a test site in Sweden, with the objectives of: testing geophysical meth-ods of locating defects in the structure; and, using geotechnical instruments to check the behaviour of the dam during first impounding, and subsequently during fluctuations of the reservoir level. The main purpose was to investigate if conventional geophysical methods can be used to detect embedded faults at a rockfill embankment dam in a blind test. Initially, a number of scientists with different specializations in geophysical methods were invited to perform a synthetic pre-simulation assessement to determine if their non-destructive methods would reveal the defects. The test facility is described, the embankment dam constructed for the study and some highlights of the results.