Manzanares (river) protected as the "Parque Regional de la Cuenca Alta del Manzanares", a nature reserve which is recognised as a biosphere reserve by UNESCO. The Manzanares flows in a south-eastern direction from its source, and passes through the medieval town of Manzanares el Real where it is dammed to form the Santillana reservoir, one of the most important water supplies for the capital. The river then takes a southern direction and enters the Monte del Pardo, an ecologically valuable area on the edge of Madrid. The river is canalised where it passes through the built-up areas of the city. As at
Eresma River several streams forms the river. Most of these streams descend from the slopes of mountains like Peñalara, Siete Picos and Montón de Trigo. Its most important tributaries are Moros and the Voltoya that flow northward, passing through San Ildefonso, Palazuelos, and through the city of Segovia; which it surrounds in a closed meander. Eresma river then runs northwest, passing near Hontanares, Los Huertos, Bernardos, Navas de Oro, Coca and Villeguillo. It enters the province of Valladolid through Olmedo, Pedrajas, Alcazarén and Hornillos. Later it flows from the right into the Adaja in Matapozuelos. Eresma river has pluvio-nival regime, which means