The lock and sea defence at Dokkumer Nieuwe Zijlen form a national monument dating from 1729. Next to it stands an obelisk monument reading: “Ter Eewiger Gedagtenis van de overdijking van ’t Dokkumer Diep” (“In everlasting memory of the dyking/embankment of the Dokkumer Diep”). The inn next door also dates from 1729.
The lock is part of a two-kilometre “afsluitdijk”. This made the old sea lock near the city of Dokkum unnecessary, and it also reclaimed 600 hectares of land. The complex consists of three lock basins. Via the sluices, water could be discharged from the Friese boezem into the Waddenzee. And via the lock chamber, shipping could pass through towards the Waddenzee.
This robust and ingenious construction was designed by mathematician-engineer and dike builder Willem de Lorée of the University of Franeker.
The complex, with fourteen pairs of doors, did its job until the Lauwerszee was closed off in 1969. Once new locks were built near Lauwersoog, the lock at Dokkumer Nieuwe Zijlen lost its main function. Even so, this place is still important in Fryslân’s water management: the Willem Lorésluis still helps discharge excess water from the province of Fryslân.
