These data files include georeferenced water-quality data with associated time stamps (Central Standard Time) for basic water-quality parameters as measured by a towed multiparameter sonde (YSI 6920 sonde) from a manned boat in the Chicago Sanitary and Ship Canal. Data were collected on February 25-27, 2010, and again on March 2-3, 2010. The data collected in February 2010 had the sonde on a fixed mount about 1 foot below the surface. The data collected in March 2010 had the sonde on a towed cable about 7-9 feet below the surface. All data have been edited and reviewed. Omitted data have been flagged with a data value of -9999 in the data files.