Lock 15

Lock 15, built between 1759 and 1804, is a single lock that continues the ascent of the North Branch near Osorno la Mayor. Its oval basin, 25.10 meters long, 9.50 meters wide, and 3.20 meters high, is constructed of limestone masonry, a durable material that has allowed the essential structure of the hydraulic work to be preserved. On the right bank, a spillway connects via an underground conduit to the diversion channel on the same bank, discharging against the basin wall before rejoining the canal. The intake that fed the millrace to the adjacent building originates at the left wing of the upper entrance, crossing under the towpath via a buried pontoon bridge and returning to the canal approximately 70 meters downstream.

The complex is structured around several secondary elements. The bridge over the lock, also from the Enlightenment period, features a semicircular arch in limestone ashlar, with stone wing walls and parapets. Its condition is fair, as part of a parapet is missing, but it retains its essential structure and characteristic smooth impost. Two auxiliary bridges, also made of limestone ashlar, are preserved at the diversion dam; these allowed for the continuity of the towpath. They are in good condition and maintain the authenticity of the original construction. Next to them is the lock keeper’s house, a single-story building with pressed brick walls, a wooden frame, and a ceramic tile roof. Although its condition is fair and the stable roof is gone, it retains original facades and structural elements that evoke daily life connected to the maintenance of the canal. A ruined area, the remains of the old mill associated with the lock, completes the complex. It is proposed to reconstruct the mill’s layout to improve the historical understanding of the site.

A visit to Lock 15 is an ideal setting to discover how 18th-century engineering was integrated into the landscape and to enjoy a heritage site that still preserves the memory of the Canal de Castilla in each of its elements.