ROWLETT CREEK. Rowlett Creek rises four miles west of McKinney in west central Collin County (at 33°12' N, 96°45' W). It was probably named for Daniel Rowlett, who owned the surrounding land. The stream flows southeast for twenty-six miles. Until the late 1960s it flowed into the East Fork of the Trinity River in southwestern Rockwall County. In 1970 it was diverted to empty on Lake Ray Hubbard (at 32°54' N, 96°35' W). The perennial stream is intermittent in its upper reaches. The watershed area of 137.6 square miles includes the cities of McKinney, Plano, and Allen in Collin County; Richardson and Garland in Dallas County; and Rowlett in Rockwall County. The moderately steep to gently rolling terrain is surfaced by blackland clay over limestone of the Austin Chalk formation. Because the southern portion of the creek was subject to seasonal floodings, several dams were built on the creek in the late 1960s and early 1970s. During this same period the dramatic growth of Plano, Allen, Richardson, and Garland changed the profile of the Rowlett Creek watershed from primarily rural to highly urban.