This report presents acoustical data that were collected by the National Park Service Natural Sounds Program at Sand Creek Massacre National Historic Site between 2009 and 2011. Data were collected to provide park managers with information about the acoustical environment, noise sources, and to provide an estimate of natural ambient sound levels throughout the park.

In April and May of 2008, an acoustical monitoring system was deployed at Mission San Juan in San Antonio Missions National Historical Park (SAAN). The system gathered Type-1 one second sound pressure levels over 33 1/3 octave band frequencies, as well as continuous digital recordings for 27 days. This sampling scheme conformed to the National Park Service Natural Sounds Program's protocol for air tour management planning. The purpose of this data collection effort was to quantify existing sound level conditions at the park and create a detailed inventory of all audible sound sources.

In 2011, one acoustical monitoring system was deployed at Saint Croix National Scenic Riverway (SACN) for 34 days. The purpose of this monitoring effort was to characterize existing sound levels and estimate natural ambient sound levels as well as identify audible sound sources prior to the proposed re-opening of the Zavoral Gravel Mine in Scandia, Minnesota. At the time that this report was written, an EIS was being prepared for the reopening of the gravel mine, as required under the State of Minnesota Rules of decision-making.