Heathcote River/Ōpāwaho catchment
We are working with the Christchurch West Melton Water Zone Committee, Christchurch City Council, local rūnanga, and community groups and organisations to improve water clarity in the streams and rivers in this catchment.
By helping people understand what stormwater is and where it ends up, we hope to work together to increase public awareness and understanding of the challenges our urban waterways face.
The largest waterway in the catchment, the Heathcote/Ōpāwaho River is fed by Cashmere Stream and needs your help to improve the water clarity.
Soil (sediment) that leaves properties throughout the catchment ends up on footpaths, gutters, and roads, and enters the stormwater network.
This network goes into the Cashmere Stream, and then into the Heathcote/Ōpāwaho River. Sediment from these drains smothers the habitat for fish and insects making it harder for fish to see their food and makes the river dirty and more likely to flood.
To help, you can become a Stormwater Superhero by doing things like:
- picking up dog poo and rubbish, and disposing of it properly
- washing the car on the grass verge or your lawn
- keeping dirt on your property when doing construction
- reporting dirt or sediment leaving building sites and going onto footpaths or roads by phoning Environment Canterbury on 0800 765 588 (24/7) or report it using the Snap, Send, Solve app.
Running along the northern base of the Port Hills and into the Ōpāwaho/Heathcote River, Cashmere Stream faces suspended sediment issues and low water clarity as a result.
The Cashmere Stream Care Group collected water clarity data from November 2010 to February 2018. The results showed that water clarity in Cashmere Stream is degrading over time, with clarity significantly worse in the hill area, and during rain events - when more sediment enters the waterways.
Improving Cashmere Stream's water clarity
To improve water clarity in Cashmere Stream, more sediment and erosion prevention on development sites, and public education on the hill catchments is needed. These areas are where sediment comes from, and that results in poor water clarity for local waterways.
Key sources of sediment coming from the Port Hills include:
- exposed soils from forestry and inadequate forestry riparian buffers
- poorly constructed and maintained recreation tracks
- unfenced waterways resulting in loss of vegetation
- loss of vegetation due to fire
- exposed soils during subdivision development, and
- poorly performing and managed sediment and erosion control strategies.
Learn more about sediment in waterways, by watching this video with EOS Ecology Principal Scientist, Shelley McMurtrie.
If you see sediment or erosion issues during heavy rains or surrounding building/construction sites, call our incident response hotline on 0800 765 588. Once we know, we can investigate.
Christchurch West Melton Water Zone Working Group
The Christchurch West Melton Water Zone Committee has a Working Group focused on identifying actions to raise awareness of the sediment issues in the Cashmere Catchment, and suggesting improvements to how the issues are managed.
If you would like to find out more about the Working Group and wider Committee’s work, or contribute ideas, please contact us.
Haytons Stream forms part of Christchurch’s stormwater network, which is owned and operated by Christchurch City Council.
The stream runs through the middle of a large industrial area in Hornby-Wigram and the Christchurch West Melton Water Zone Committee has identified it as a priority catchment due to its high level of pollution.
Run-off from footpaths, roads and gutters during rain events carries contaminants into the waterway.
Environment Canterbury is working with businesses in the industrial area to ensure any stormwater leaving their sites is as clean as possible.
Curletts Stream is similar to Haytons Stream in that it is spring-fed and flows through an industrial area before entering the Heathcote River/Ōpāwaho.
Environment Canterbury staff have visited businesses in the catchment to help them to minimise the amount of contaminants running off their sites.
We have a ‘Sediment Toolbox’ to help everyone involved with any kind of earthworks on the land or near water reduce their sediment impact.
Check out the toolbox here to see resources, photos, videos and more.