YANKEE CREEK. Yankee Creek rises just north of Heath in southwest Rockwall County (at 32°51' N, 96°28' W) and runs west for 3½ miles, over flat to rolling land surfaced with dark, calcareous clays that support mesquite and cacti. For most of the county's history the Yankee Creek area has been used as rangeland and cropland. Yankee Creek joined the East Fork of the Trinity River until the 1970s, when the stream was diverted to enter the newly constructed Lake Ray Hubbard (at 32°50' N, 96°31' W) just southwest of Heath.