The water-level database for the Death Valley regional groundwater flow system in Nevada and California was updated. The database includes more than 54,000 water levels collected from 1907 to 2007, from more than 1,800 wells. Water levels were assigned a primary flag and multiple secondary flags that describe hydrologic conditions and trends at the time of the measurement and identify pertinent information about the well or water-level measurement. The flags provide a subjective measure of the relative accuracy of the measurements and are used to identify which water levels are appropriate for calculating head observations in a regional transient groundwater flow model. Included in the report appendix are all water-level data and their flags, selected well data, and an interactive spreadsheet for viewing hydrographs and well locations.