TERRELL RESERVOIR. Terrell Reservoir is in the Trinity River basin five miles east of Terrell on U.S. Highway 80 in Kaufman County (at 32°43' N, 96°10' W). The reservoir, also known as Terrell City Lake, was formed by the impounding of Muddy Cedar Creek in 1955. It is owned and operated by the city of Terrell and serves as a municipal water supply and recreation area. Terrell Reservoir drains a fourteen-square-mile area; it comprises a surface area of 885 square miles. Its normal elevation is 503 feet above sea level, and its spillway elevation is 504 feet. The reservoir's storage area is 8,300 acre-feet. At its emergency spillway crest elevation, the reservoir's capacity is 12,400 acre-feet and its surface area is 1,150 acres.