Camilo Jose Cela travelled though the Alcarria in 1946, the Entrepeñas reservoir was inaugurated in 1956 so it is not described in the book. It is located in the lower Guadalajara Alcarria, on the riverbed of the Tagus. It also receives water from the Valdetrigo, Barranco Grande, La Solana and Ompolveda, among other rivers.