Kahika Stream Assessment
Summary of report findings
The Kahika Stream catchment has been developed for residential use relatively recently during the last 30-50 years. Prior to this the area was in rural use supporting fruit farming and before that was cloaked with kauri forest for thousands of years. The catchment now has 81% residential land use, along with areas of road (13%) and bush (6%), and is largely developed to capacity. Surrounding urban development has affected the stream by increasing flows resulting in erosion of the stream bed and banks.
Documents
Kahika Stream report PDF 
(995KB)
Kahika Stream maps (PDFs)
Links
North Shore stream assessments overview page
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Cleaning up the Kahika Stream
The Kahika Stream is under threat from pollutants such as oil, chemicals, rubbish and paint, which enter the stream from the stormwater system.
| Length |
4.6km |
|
| Size Of Catchment | 181ha | |
| Vegetation Cover | 22% (39ha), largely following the stream course. | |
| Imperviousness | 30% | |
| District Plan Land Use | Business | <1% |
| Recreation | 7% | |
| Residential | 81% | |
| Road | 13% | |
| Recreational Use | Medium, some known public use of the stream locality. | |
| Receiving Environment | Kaipatiki Creek, Hellyers (Oruamo) Creek, Upper Waitemata Harbour. | |
| Substrate | Primarily silt/mud with sections of bedrock in the upper main channel and Tributary 7. Heavy sediment deposition throughout. | |
| Natural Wetlands | 0 | |
| Artificial Wetlands | 1 | |
| Periphyton | Below nuisance levels. | |
| Macrophytes | No management issues. | |
| Macroinvertebrates | Indicative condition in the lower Kahika Stream is considered moderate and in the upper section of the stream is poor. | |
| Fish | 5 species of native fish + koura. | |
| Potential Man-Made Barriers to Fish Passage to Upstream Habitat | 5 (+ 6 natural potential barriers). | |
| Channel Modification | Nil. | |
| Erosion around Structures | Amongst the worst on the North Shore, 40% of structures have some erosion. 5 structures with slight erosion, 6 with moderate erosion, and 8 with severe erosion. | |
| Bank Erosion | Significant erosion throughout ranging from slight to moderate. | |
| Temperature | Generally low but likely to be higher during summer. | |
| Suspended Solids, Turbidity And Visual Clarity | Typical for urban streams. | |
| Oxygen and Oxygen Demand | Good oxygen saturation levels, dissolved oxygen of 8.3 and 8.2 g/m3. A range of oxygen demand levels. | |
| Nutrients |
Median ammonia 0.05 mg/l. Nitrate 0.147 and 0.368 mg/l. |
|
| Contaminants | Typical for North Shore streams. | |
| Bacteria and Pathogens | Levels of indicator bacteria indicate suggest the stream is not suitable for contact recreation. | |
| Sediment Quality | No data. | |
| Debris | Significant inorganic and organic debris. | |
| Stream Grouping | Group 2, High value low disturbance | 12% |
| Group 3a, Urban semi-modified | 48% | |
| Group 3b, Urban modified | 39% | |
| Group 4, Concrete lined channel | - | |
| Group 5, Piped section | - | |