Wairau Creek Stream Assessment
Summary of report findings
Prior to development, the Wairau Valley was largely swamp land with three tributary catchments, rolling hills that were steep in places and a main channel that was overgrown with willows. The land was subsequently drained and raised for use as pasture and the steeper areas lowered to allow industrial and residential construction following the opening of the Auckland Harbour Bridge. The catchment is now fully developed with primarily low density residential land use (58%) and contains the North Shore’s main industrial area along with commercial shopping areas in Milford, Sunnynook and Glenfield. The northern motorway also passes through the catchment. The Wairau Creek is the most modified watercourse on the North Shore.
Wairau Creek report PDF 
| Length | 17.9 km | |
| Size Of Catchment | 1,318ha | |
| Vegetation Cover | 7% (97ha), scattered in small pockets throughout the catchment. | |
| Imperviousness | 48% | |
| District Plan Land Use | Business | 14% |
| Recreation | 9% | |
| Residential | 59% | |
| Road | 18% | |
| Special Purpose | 0.15% | |
| Recreational Use | Low, no significant known public use. | |
| Receiving Environment | Wairau Estuary, Milford Beach, Hauraki Gulf. | |
| Substrate | Predominantly concrete lined. | |
| Natural Wetlands | 1 | |
| Artificial Wetlands | 4 | |
| Periphyton | Significant densities in main channel – above nuisance levels in some tributaries. | |
| Macrophytes | Generally good, some management issues in Tributary 7. | |
| Macroinvertebrates | Low MCI score and %EPT relative to other North Shore streams. | |
| Fish | 5 species of native fish + introduced mosquitofish | |
| Potential Man-Made Barriers to Fish Passage to Upstream Habitat | 16 | |
| Channel Modification | Extensive – significant proportion of main channel and tributaries straightened and lined or piped. | |
| Erosion around Structures | 3 outfalls with slight erosion, 3 with moderate, 1 with severe | |
| Bank Erosion | Minimal erosion due to concrete lining of banks. | |
| Temperature | No data | |
| Suspended Solids, Turbidity And Visual Clarity | Average and below average suspended solids. Below and above average turbidity. High clarity recorded during stream walk survey. | |
| Oxygen and Oxygen Demand | Average relative to other North Shore streams. | |
| Nutrients | Low ammonia and nitrate levels. | |
| Contaminants | Significantly elevated concentrations of copper and zinc. | |
| Bacteria and Pathogens | Levels of indicator bacteria suggest the creek is not suitable for contact recreation. | |
| Sediment Quality | No data. | |
| Debris | Little organic debris. Significant amounts of inorganic debris. | |
| Stream Grouping | Group 2, High value low disturbance | - |
| Group 3a, Urban semi-modified | 9% | |
| Group 3b, Urban modified | 15% | |
| Group 4, Concrete lined channel | 47% | |
| Group 5, Piped section | 29% | |