The source is disputed, tradition holds that it rises at an artesian well, the Fuente de Cella, at the base of the Sierra Albarracín in Teruel province.

[1] It is now thought that the stretch of river between Cella and Monreal del Campo is the remains of an 18th-century canal which was cut to drain the Laguna Cañizar at Villarquemado.

[2] The Ojos de Monreal are a series of artesian wells which form pools connected by small channels.

[3][11] Further downstream in the valley between Manchones and Morero, birdlife includes goshawks, eagles, orioles, robins, finches, hoopoe and kestrels.

[12] In 2000, the Asociación Naturalista de Aragón strongly condemned cleaning works by the regional government, which they said were systematically destroying riparian vegetation, killing fish and upsetting the ecology of the river in the reaches between Daroca and Calatayud.

[13] In November 2009, an investigation into soil erosion in the Jiloca basin was announced, with the intention of determining suitable future land use strategies.

[5][15] There is one tributary, the Pancrudo, which rises 3 kilometres (1.9 mi) above the pueblo of Pancrudo, in Teruel province and flows generally north east past Torre los Negros, Navarette del Rio and Lechago before joining the Jiloca at Luca de Jiloca after 46 kilometres (29 mi).