Castor Bay Stream Assessment
Summary of report findings
Castor Bay Stream catchment has been largely developed to capacity since the mid 1900s and consists primarily of low density residential land use (77%). The Castor Bay Stream is a heavily modified stream with extensive lengths which have been culverted or lined.
Documents
Castor Bay Stream report PDF 
(822KB)
Castor Bay Stream maps (PDFs)
Links
North Shore stream assessments overview page
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| Length |
2.4km |
|
| Size Of Catchment |
71ha |
|
| Vegetation Cover |
23% (17ha), largely to the north of the catchment. |
|
| Imperviousness |
37% |
|
| District Plan Land Use | Business |
0.03% |
| Recreation |
8% |
|
| Residential |
77% |
|
| Road |
14% |
|
| Recreational Use |
Medium, some known public use of stream locality. |
|
| Receiving Environment |
Castor Bay Beach, Hauraki Gulf. |
|
| Substrate |
Predominantly silt/mud + concrete. |
|
| Natural Wetlands |
2 |
|
| Artificial Wetlands |
Nil |
|
| Periphyton |
Below nuisance levels. |
|
| Macrophytes |
No management issues. |
|
| Macroinvertebrates |
Indicative of moderate condition. |
|
| Fish |
2 (possibly 3) species of native fish. |
|
| Potential Man-Made Barriers to Fish Passage to Upstream Habitat |
12 (+ 3 natural potential barriers). |
|
| Channel Modification |
Heavily modified throughout by culverting, piping and channel lining. |
|
| Erosion around Structures |
2 structures with moderate erosion + 1 with severe erosion. |
|
| Bank Erosion |
Overall severe erosion throughout. Slight erosion within the low main channel and Tributaries 1 & 2, moderate erosion in Tributary 2, and severe erosion in the upper main channel and Tributary 3. |
|
| Temperature |
One (autumn) measurement of 17.4°C. |
|
| Suspended Solids, Turbidity And Visual Clarity |
Suspended solids measured at 289g/m3 during dry weather. Low clarity compared to other North Shore streams. |
|
| Oxygen and Oxygen Demand |
Dissolved oxygen recorded at 9.1g/m3. |
|
| Nutrients |
No data. |
|
| Contaminants |
No data. |
|
| Bacteria and Pathogens |
Levels of indicator bacteria indicate the stream is not suitable for contact recreation. |
|
| Sediment Quality |
No data. |
|
| Debris |
No significant debris. |
|
| Stream Grouping | Group 2, High value low disturbance |
- |
| Group 3a, Urban semi-modified |
11% |
|
| Group 3b, Urban modified |
38% |
|
| Group 4, Concrete lined channel |
44% |
|
| Group 5, Piped section | 5% | |