Water resources data for Montana for the 2003 water year, volumes 1 and 2, consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels in wells. This volume contains discharge records for 132 streamflow-gaging stations; stage or content records for 5 lakes and large reservoirs and content for 5 smaller reservoirs; and water-quality records for 66 streamflow stations (34 ungaged), and 7 ground-water wells. Additional water year 2003 data collected at crest-stage gage and miscellaneous-measurement sites were collected but are not published in this report. These data are stored within the District office files in Helena and are available on request. These data represent part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Montana.