HHNK in figures

Reference date: January 1, 2024

General

 
Area of administrative jurisdiction196,600 hectares 
  - rural area 164,809 hectares 
  - urban area 31,791 hectares
Number of municipalities (entirely or partially)28
Number of inhabitants1,210,655 (1.21 million)

Water system management (quantity)

 
Area of drained land177,029 hectares
  - number of polder areas230
  - number of monitoring areas2.697
Surface area of freely draining area 19,571 hectares
Open water area (total)15,421 hectares (8%)
  - chest water2,950 hectares
  - polder water, other water12,471 hectares
Length of primary waterways3,600 kilometre
  - inland waters529 kilometre
Length of other waters under management16,907kilometre
Number of mills (total)2.269
  - sump pumps4
  - polder pumping stations363
  - other1.902
Number of locks (total)87
  - sluice gates48
  - other39
Number of weirs5.422
Number of divers, syphons, and siphons60.466
Number of fish passages ​45

Flood defense management

 
Length of primary flood defenses269kilometre
  - hard barriers176kilometre
  - sandy coast (dunes)93 kilometre
Length of non-primary flood defenses1,289 kilometre
Length of regional flood defenses (with IPO standard)1,065 kilometre 
Length of other flood defenses224kilometre
Total length of flood defenses1,558 kilometre
Number of denominations162

Road management

 
Area of responsibility: road maintenance28,122 hectares
Length of roads under management (including bicycle paths and footpaths)420 kilometre
- Roads on flood defenses202 kilometre
Number of light poles​2.957

Wastewater treatment  

 
Number of sewage pumping stations 302
Length of pressure pipes607 kilometre
Number of sewage treatment plants (STPs) 15
Amount of treated wastewater (per year)± 100 billion litre
Number of sludge drying installations (SDIs)1
Number of IBA systems654

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