The Noordpolderzijl discharge sluice has been restored to its former glory

Restoration of the lock gates

The discharge sluice at Noordpolderzijl underwent a thorough renovation eight years ago. The masonry and jointing of the historic sluice were thoroughly restored at that time, but the restoration remained incomplete because the two ebb gates and two flood gates were in worse condition than expected. After inspection, it became clear that reinstallation was no longer possible. To restore this water-authority heritage site to its original condition, the water authority, in collaboration with Landschapsbeheer Groningen, had new gates manufactured, allowing the restoration to be completed after all.

Water authority director Bert Wiersema states: “By preserving this former discharge sluice as a historical feature, we are passing on this landscape to future generations. The restoration also enhances the experience of this unique and highly recognisable spot in the Groningen landscape for recreational users and tourists.”

An appreciation for flora and fauna

The existing flora and fauna were taken into account whilst the work was carried out. For example, the sluice walls are covered with rock ferns. This protected and relatively rare plant species is typically found in shady areas near old walls. The ferns were preserved by carefully grouting around the plants. In addition, nets were placed near the lock as a precaution to prevent birds from nesting during the restoration work.

Discharge of seawater from the Noordpolder

Historically, the discharge sluice was important for water management and former shipping in the province of Groningen. In 1811, with the reclamation of the Noordpolder, the Noorder dyke was constructed. The discharge sluice was built at the same time. Excess water from the Noordpolder could be discharged into the Wadden Sea via the sluice. A modern, electric pumping station was built next to the sluice in 1981, and the old sluice was no longer needed. Shortly thereafter, as part of the Delta Act, the sea dyke was raised. On the Wadden Sea side, the discharge sluice was incorporated into the dyke body. Above the passage, a commemorative stone bearing the year 1811 is visible. Commemorative stones have also been set into both sluice walls to mark later repairs and restorations of the sluice. Next to the sluice still stands the old Zielhoes from 1812, the former residence of the lockkeeper. The former lock gates have been given a home near the adjacent Zielhoes as a work of art.

Waddenkronieken (Wadden heritage)

The restoration of the old discharge sluice is one of the projects in the Waddenkronieken programme. This programme brings the unique history of the Wadden Sea coast back to life by uncovering and restoring forgotten stories and landscape features. Landschapsbeheer Groningen is one of the partners in this project. “It’s wonderful that the sluice gates, restored to their former glory, are the first completed ‘Waddenkroniek’ project,” says Peter Hellinga, director of Landschapsbeheer Groningen. 

“The first visible result after years of preparation for this programme; a beautiful symbol.” Provincial Executive member Nadja Siersema also speaks enthusiastically about the restoration of the old sluice. “This fine example of craftsmanship does justice to Noordpolderzijl’s role and uniqueness in our province as the gatekeeper to the sea.”

Project partners and funding

The work on the old discharge sluice was carried out by Wieringa Bouwadvies and the contractor Koninklijke Oosterhof-Holman. In addition to this old sluice in Noordpolderzijl, two more old “sluices” (former tidal sluice and barriers) near Warffum and Oudeschip are being restored as cultural-historical elements. The restoration of these two hydraulic-engineering structures is also carried out in cooperation with Landschapsbeheer Groningen, as part of the Waddenkronieken programme. The work on these three sites is made possible in part by contributions from Noorderzijlvest Water Authority (€165,000), the Wadden Fund (€182,000), and the provincial executive of Groningen (€108,000).