| Piedra | |
| Map: | Cuenca del rio Riedra.jpg |
| Subdivision Type1: | Country |
| Subdivision Name1: | Spain |
| Subdivision Type3: | Region |
| Subdivision Name3: | Castile-La Mancha, Aragón |
| Subdivision Type4: | District |
| Subdivision Name4: | province of Guadalajara, province of Zaragoza |
| Subdivision Type5: | City |
| Subdivision Name5: | Campillo de Dueñas, Cimballa, Nuévalos, Carenas, Castejón de las Armas |
| Length: | 76km (47miles) |
| Discharge1 Avg: | 1.22m3/s |
| Source1: | Campillo de Dueñas |
| Source1 Location: | province of Guadalajara, Castile-La Mancha, Spain |
| Source1 Coordinates: | 40.833°N -1.655°W |
| Source1 Elevation: | 1195m (3,921feet) |
| Mouth: | Castejón de las Armas |
| Mouth Location: | province of Zaragoza, Aragón, Spain |
| Mouth Coordinates: | 41.319°N -1.81°W |
| Mouth Elevation: | 590m (1,940feet) |
| Tributaries Left: | Mesa River |
| Tributaries Right: | Ortiz, Munebraga |
| Custom Label: | River system |
| Custom Data: | Ebro |
The Piedra (Spanish; Castilian: Río Piedra) is a river in the Iberian System area, Spain. It is a tributary of the river Jalón. The waters have a high concentration of calcium carbonate which is deposited on plant life near the source, giving the river its name Río Piedra, which means 'stone river' in English.
The population of the endangered European freshwater crayfish in the river and its tributaries has practically disappeared owing to the introduction of the North American signal crayfish (Pacifastacus leniusculus).[1]
It rises near Campillo de Dueñas, in the province of Guadalajara, Castile-La Mancha. The Piedra has an irregular flow, due to the long sunny season of the summer months, with often heavy rainfall in the spring and autumn. The mean discharge at Monasterio de Piedra is 1.22m3/s.[2]
The river is often said to rise at Cimballa, in the province of Zaragoza, but it actually rises near Campillo de Dueñas, although the upper reaches are often dry in the summer months. Springs at Campillo amplify the flow, so that it always has water below this point.
From Cimballa, the Piedra flows down to the water gardens of the Monasterio de Piedra where the calcareous water has formed a Karst topography of waterfalls and rocky pools. The place is popular with visitors, for it is a kind of oasis in the surrounding arid and harsh mountainous landscape.[3] [4] After leaving the Monasterio the river descends to La Tranquera Dam at Nuévalos. The rivers Mesa, Ortiz and Munebraga also feed the reservoir and may be considered tributaries of the Piedra. From La Tranquera, the river flows past Carenas and joins the Jalón near Castejón de las Armas and Ateca.
In 1988, the Government of Aragón established a fish reserve at Monasterio in order to provide fish for replenishing the stocks of Aragón's rivers.[5]