The islands of the Sacramento-San Joaquin Delta have been subject to subsidence since they were first reclaimed from the estuary marshlands starting over 100 years ago, with most of the land currently lying below mean sea level. This area, which is the primary water resource of the state of California, is under constant threat of inundation from levee failure. Since July 2009, we have been imaging the area using the quad-polarimetric UAVSAR L-band radar, with eighteen data sets collected as of April 2011. Here we report results of our polarimetric and differential interferometric analysis of the data for levee deformation and land surface change. ?? 2011 IEEE.