Summary of report findings
Development has only occurred relatively recently within the Alexandra Stream catchment. The Rosedale Waste Water Treatment Plant lies within the north of the catchment which otherwise contains a mixture of light industrial, commercial and residential land uses. Future development is expected to decrease the area of remaining rural land to accommodate an increase in residential use as well as small increases in industrial and commercial areas.
As a tributary to the larger Oteha Valley Stream, the Alexandra Stream shares some of the same natural characteristics. While the head of the stream has been modified by residential development activity, the lower channel retains a more natural form.
| Length |
5km |
| Size of Catchment |
270ha |
| Vegetation Cover |
12% (34ha), associated mainly with the central main channel and Tributaries 3 + 4. |
| Imperviousness |
39% |
| District Plan Land Use |
Business |
19% |
| Recreation |
23% |
| Residential |
38% |
| Road |
17% |
| Special Purpose |
2% |
| Rural |
<1% |
| Structure Plan Area |
<1% |
| Recreational Use |
High, known high public use of stream locality. |
| Receiving Environment |
Oteha Valley Stream into the Lucas Creek. |
| Substrate |
Stable bedrock within the lower channel, otherwise predominantly silt/mud. |
| Natural Wetlands |
1 |
| Artificial Wetlands |
6 |
| Periphyton |
Below nuisance levels except for pond at the head of Tributary 2. |
| Macrophytes |
Possible management issues for the lower main channel and Tributary 4, probable management issues within Tributary 2. |
| Macroinvertebrates |
Moderate |
| Fish |
6 native fish species + koura |
| Potential Man-Made Barriers to Fish Passage to Upstream Habitat |
5 |
| Channel Modification |
Some modification through most of streams. |
| Erosion around Structures |
1 structure with slight erosion, 2 with moderate erosion + 3 with severe erosion. |
| Bank Erosion |
Overall slight but severe erosion in the upper main channel and Tributary 4. |
| Temperature |
Within acceptable range (1 measurement). |
| Suspended Solids, Turbidity And Visual Clarity |
High clarity compared to other North Shore streams. |
| Oxygen and Oxygen Demand |
Acceptable oxygen levels (1 measurement). |
| Nutrients |
No data. |
| Contaminants |
No data. |
| Bacteria and Pathogens |
No data. |
| Sediment Quality |
No data. |
| Debris |
Insignificant. |
| Stream Grouping |
Group 2, High value low disturbance |
10% |
| Group 3a, Urban semi-modified |
23% |
| Group 3b, Urban modified |
45% |
| Group 4, Concrete lined channel |
- |
| Group 5, Piped section |
22% |
