The Charca de la Esclusa 4 is located in the province of Palencia, within the Tierra de Campos region, next to Lock number four of the Campos Branch of the Canal de Castilla, in the municipality of Castil de Vela.
Its origin is directly related to the construction and operation of the Canal de Castilla between the 18th and 19th centuries. Unlike other pools in the system, the Lock 4 Pool was formed very directly by the water drop generated at the lock, as well as by seepage from the canal basin and the alteration of the natural drainage of the surrounding land.
It is a small pond with a water level that can be seasonal or semi-permanent, highly dependent on the hydraulic regime of the canal and the lock itself. Its banks are home to marsh vegetation that adds ecological diversity to a landscape dominated by the cereal crops of Tierra de Campos, creating a significant contrast between historical engineering and the natural environment.
The wetland is situated within an area of significant heritage value, where the remains of the old warehouses and the lock keeper’s house associated with the lock are preserved—although in a state of disrepair. This complex reinforces the historical and cultural significance of the site, which has been declared a Cultural Heritage Site as part of the Canal de Castilla.
The Lock 4 Pond is a particularly clear example of how a hydraulic infrastructure designed for navigation and grain transport indirectly but immediately generated new ecosystems that are now recognized and protected.
