Lock 4

Lock 4, built between 1759 and 1804, is a single-stage lock with an oval basin that continues the ascent of the North Branch in a section where the canal approaches Herrera de Pisuerga. Measuring 23.30 meters long, 9.60 meters wide, and 3.70 meters high, it is constructed of sandstone masonry and retains the original supports for the operating winches, essential for understanding how the gates were operated. Its design includes a spillway on the left bank, which drains through a tunnel and a buried circular concrete channel before rejoining the canal downstream. On the right wing, an intake nozzle diverts part of the flow to an adjacent building, reflecting the close relationship between the hydraulic infrastructure and its associated productive uses. Although its state of preservation is not excellent, the original hydraulic structure remains intact.

Among the secondary features, the bridge over the lock stands out, also built between 1759 and 1804. Constructed of sandstone ashlar with a semicircular arch, it has stone wing walls and parapets, although the upstream parapet is missing. It maintains the solidity and proportions characteristic of the canal’s engineering, ensuring passage between banks without interfering with the lock’s operations. Further along, the bridge at the diversion, a small ashlar pontoon 10 meters long, ensures the continuity of the towpath on the right bank, allowing passage parallel to the canal. The old mill, located next to the water diversion, completes the ensemble. Although its characteristics are not described in detail, its presence demonstrates the canal’s use for energy and its historical connection to local productive activities.

During the visit to Lock 4, the canal reveals its technical and landscape dimensions, inviting you to discover a heritage that continues to engage with the territory and offering an evocative experience.