The River Mula, like its tributary Pliego River, is born with water collected from several mountains in the vicinity of Bullas and Cehegín. After collecting the waters of the Pliego flows into the Segura after 64 kilometers of route. Since its arrival in the vicinity of the hamlet of Niño de Mula, east of the municipality, the valley begins to green by the cultivation of the fruit trees, forming the typical landscape of the huerta muleña.
The Pliego River is affluent on the right bank of the Mula, just as it is on the Segura River. The first is born from the confluence of the rambles and ravines drain the Sierras de Espuña and Cambrón and joins the river Mula at the height of Puebla de Mula. In the kilometers before its mouth it clearly shows deep marks on its side walls. These marks are the witness of the erosive processes typical of the semi-arid basins.
The valleys of the rivers Mula and Pliego are those that make up the only part of the municipality that is dedicated to the cultivation of irrigation. This sometimes means landscape contrasts of excellent beauty between the green of the valleys and the already mentioned greyish lands and devoid of vegetation.