Abstract: This report presents a preliminary analysis of the acoustic environments of the southern resident killer whales in the Haro Strait of the Puget Sound, combining analysis of field measurements and acoustic propagation modeling for the frequency range 1-10 kHz. The Haro Strait is a highly variable acoustic environment with active commercial shipping, whale watching, and Naval activity. Southern resident killer whales are of unique public concern in this area because of increasing anthropogenic noise levels that may interfere with the animal�s foraging strategies and behavior. Predictive acoustic modeling in combination with field measurements can be used as a tool for understanding the mechanisms of impact and assessment of the risk, providing a quantitative evaluation of sound source levels in the context of complicated acoustic environments, changing background sound levels, and emerging management issues. Of principle concern in this report is background sound levels created by commercial shipping traffic or other persistent sound sources that propagate from the main shipping channel. The scope of the modeling effort encompasses numerical modeling of transmission loss and propagation at ranges of less than 10 km. Preliminary modeling results are analyzed and compared with recordings of ship noise collected in the spring/summer of 2004.