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. The well is surrounded by an elliptical parapet wall built by the Italian engineer Domingo Ferrari. 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. It is currently accepted that the Jiloca raises at the Ojos of Monreal, from the town. These are a series of ponds linked by channels. From Monreal the river flows northwards and near Luco de Jiloca, the Jiloca is joined by its only tributary, the Pancrudo, which rises away in the Sierra de la Costera. From this point there is an irrigation channel which waters a small valley near Daroca. The river flows on from Daroca in a north easterly direction, past Manchones, Morero, Montón, Morata de Jiloca, Maruenda and Paracuellos de Jiloca until it joins the Jalón between Carramolina and Calatayud. Towns named after the river are Morata de Jiloca, Paracuellos de Jiloca, Fuentes de Jiloca, Torremocha de Jiloca, Velilla de Jiloca and Villanueva de Jiloca.
Hydrographics
The Jiloca has an average flow rate of, although there are seasonal variations, due to a long dry season and wet seasons in the spring and autumn in the Meseta Central. Annual rainfall in the watershed varies from around to, with peak precipitation in May and June. The watershed covers an area of.
Natural history
The Ojos de Monreal are a series of artesian wells which form pools connected by small channels. This area is rich in wildlife, including waterfowl, grebes, wrens, kingfishers, owls, orioles and woodpeckers. There are frequently visiting wildfowl from the Laguna de Gallocanta, some away. Thickets of poplar, willow and walnut trees give plenty of shelter. The water is considered in very good condition according to the assessment of the Plan Hidrológico de la Cuenca del Ebro. Further downstream in the valley between Manchones and Morero, birdlife includes goshawks, eagles, orioles, robins, finches, hoopoe and kestrels. Deer and bobcats are found in the Sierra Santa Cruz which borders the river, hedgehogs and shrews are to be found near the banks. Trees include poplars, elm, and ash. 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. In November 2009, an investigation into soil erosion in the Jiloca basin was announced, with the intention of determining suitable future land use strategies.
History
In the past many water-mills were powered by the river, but now only ruins of these remain. The valley of the Jiloca is an ancient route between the Meseta Central, the Ebro and the coast of the Levante. Many Roman bridges remain in the pueblos of the valley.
Tributary
There is one tributary, the Pancrudo, which rises 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.
