Work activities

Read the latest information about the work to expand the De Onlanden water storage facility here. The project will continue until 2027.

Construction of weirs

In the coming months, we will be working with contractor Oosterhuis to build two new weirs at Hooiweg and modify the Doolhof weir. The weirs are expected to be completed in the spring of 2026. 

  • The new weirs will be named Vischluststuw (northern weir) and Rowolder stuw (southern weir). Under normal circumstances, the weirs lie flat, allowing the water to flow freely. When the extra water storage capacity is needed, these weirs will be raised to retain water. The plan is for work on the weirs to be so far advanced by early 2026 that we will be able to operate the northern weir manually and close off the southern channel. This means that the water storage capacity will already be partially available if needed.
  • The existing Doolhof weir will be raised and fitted with a new gate. The quays on either side of the weir will also be raised. 
Location Rowolder weir - Matsloot-Hooiweg
Location Roderwolderstuw - Matsloot/Hooiweg

What can you notice about the work?

  • Repair work on Matsloot pavement – road closure from January 5 to January 9, 2026
    The pavement at the northern weir has subsided. To prevent damage to the bridge, we will repair it in early January. This will involve closing Matsloot/Hooiweg from the Sandebuur/Matsloot/Hooiweg intersection. The closure does not apply to cyclists. 
  • At the northern weir, the reinforcing steel and concrete floor are now complete; next up are the walls and a 6-meter-wide weir gate.
  • The contractor takes nature into account during the work (breeding season, animal safety, and other measures). Ecologists from the water board are involved in the work. Read the ecological work protocol here. 
Work on the northern weir at Matsloot - Photo by Eelko Wester of Macadam.

Transport routes during work

Peat will be removed and sand brought in for the two new weirs. Soil will also be needed to raise the quays at the Doolfhof weir. In addition, equipment will be brought to the construction site. 
The transport routes are indicated on the map below. Trucks will travel via the Hooiweg/Matsloot (the red line) with materials for the construction of the weirs. Soil will be transported via the path along Cosun and the Roderwolderdijk (purple line).  
During the work on the weirs, public roads will remain accessible to other traffic. However, traffic may experience some disruption from freight traffic.  

You can zoom in on the map via this link.

Planning

  1. Currently underway: Construction of new weirs on Hooiweg - Fall 2025 – Spring 2026

    • Start of construction of two new weirs on Hooiweg/Matsloot

  2. Still to be done: Doolhofstuw - End of 2025 – spring 2026

    • The existing weir will be raised and fitted with a new gate. The quays on either side of the weir will also be raised.

  3. Still to be done: Raising quays - Early 2026-2027

    • We will ensure that more water can be stored within the existing water storage quays, which will be raised.
       

  4. Remaining tasks: Nature conservation measures - Early 2026 - 2027

    • Placing refuge islands for animals, filling in ditches, and rewetting the area by constructing channels.

  5. Still to be done: Measures for homes - End of 2026-2027

    • Measures for water management in homes

  6. Still to be done: Pumping station modifications - End of 2026-2027

    • The pumping capacity of the Sandebuur and Zanddijk pumping stations will be adjusted.

  7. Remaining tasks: Completion of additional water storage facility - 2027

    • The complete expansion of the water storage facility is now complete.