Summary of report findings
The Duck Creek catchment contains a significant area of bush reserve which encompasses a majority of the stream course. The catchment contains the Chelsea Sugar Factory with its associated ponds, the bush clad gullies of the Chatswood Reserve, and a mixture of residential and commercial land uses. Development of the catchment has included the installation of a reticulated stormwater system that collects runoff from sub-catchments and discharges it to the Duck Creek channel. A majority of the stream channel has retained its natural character.
| Length |
5.3km |
| Size of Catchment |
237ha |
| Vegetation Cover |
54.8% |
| Imperviousness |
39% |
| District Plan Land Use |
Business |
9.1% |
| Recreation/Open space |
9.1% |
| Proposed Recreation |
12.7% |
| Residential |
53.9% |
| Road |
11.6% |
| Special Purpose |
3.5% |
| Recreational Use |
High, known high public use of stream locality |
| Receiving Environment |
Waitemata Harbour at Chelsea Bay. |
| Substrate |
Predominantly bedrock with areas of silt/mud and cobbles |
| Natural Wetlands |
1 |
| Artificial Wetlands |
5 |
| Periphyton |
Below nuisance levels |
| Macrophytes |
Possible management issues in lower main channel associated with Chelsea Pons |
| Macroinvertebrates |
Moderate MCI score |
| Fish |
4 species of native fish + koura |
| Potential Man-Made Barriers to Fish Passage to Upstream Habitat |
14 including the 4 dams associated with the Chelsea
Ponds |
| Channel Modification |
Largely unmodified. Piped sections in lower reaches of Tributary 2, 3 and 4. |
| Erosion around Structures |
21 structures with slight erosion, 4 with moderate erosion, and 2 with severe erosion |
| Bank Erosion |
Slight (natural) erosion throughout with minor to moderate erosion in Tributary 3, 6, 9, and 12 |
| Temperature |
15.1 - 16.6oC indicating no adverse effect on ecology. |
| Suspended Solids, Turbidity And Visual Clarity |
Elevated suspended solids, moderate turbidity and moderate clarity to other North Shore streams |
| Oxygen and Oxygen Demand |
Low to moderate. Some organic pollution yet overall low oxygen demand. |
| Nutrients |
Typical concentrations compared to other North Shore streams. |
| Contaminants |
Limited information, but generally the same as other North Shore streams with similar catchment landuse. Close proximity to Chelsea Sugar Factory increases potential for sugar spills into water course. |
| Bacteria and Pathogens |
Levels of indicator bacteria indicate the stream is not suitable for contact recreation. |
| Sediment Quality |
Significant, poor quality sedimentation in Pond 2, Pond 3 and Pond 4. |
| Debris |
Insignificant. Some inorganic rubbish present adjacent to stormwater outfalls and upper reach of Tributary 3. |
| Stream Grouping |
Group 2, High value low disturbance |
9.9% / 0.53 km |
| Group 3a, Urban semi-modified |
51.6% / 2.75 km |
| Group 3b, Urban modified |
27.7% / 1.47 km |
| Group 4, Concrete lined channel |
0 km |
| Group 5, Piped section |
10.9% / 0.58 km |
