Given the question: What counties was the CEW in?  Answer the above question based on the context below:  The Clinton Engineer Works (CEW) was the production installation of the Manhattan Project that during World War II produced the enriched uranium used in the 1945 bombing of Hiroshima, as well as the first examples of reactor-produced plutonium. It consisted of production facilities arranged at three major sites, various utilities including a power plant, and the town of Oak Ridge. It was in East Tennessee, about 18 miles (29 km) west of Knoxville, and was named after the town of Clinton, eight miles (13 km) to the north. The production facilities were mainly in Roane County, and the northern part of the site was in Anderson County. The Manhattan District Engineer, Kenneth Nichols, moved the Manhattan District headquarters from Manhattan to Oak Ridge in August 1943. During the war, Clinton's advanced research was managed for the government by the University of Chicago. Construction workers were housed in a community known as Happy Valley. Built by the Army Corps of Engineers in 1943, this temporary community housed 15,000 people. The township of Oak Ridge was established to house the production staff. The operating force peaked at 50,000 workers just after the end of the war. The construction labor force peaked at 75,000 and the combined employment peak was 80,000. The town was developed by the federal government as a segregated community; black residents lived only in an area known as Gamble Valley, in government-built "hutments" (one-room shacks) on the south side of what is now Tuskegee Drive.
The answer is:
Anderson County