Healthy streams

Algae are important components of stream ecosystems – they are not necessarily something evil that needs to be eradicated or managed in any way. Thin films of green or brown algae (see Indicator taxa) on streambeds can be important food resources for grazing invertebrates, and they are nature’s biological filters helping to remove (or bind up) all sorts of contaminants from the water. Healthy streambed algal communities can take many forms – different combinations of taxa including diatoms, green algae, red algae and cyanobacteria (blue-green algae) occur in different high quality streams, and these communities will change in composition with seasons and with flow events. These healthy stream communities are likely to occur in bush covered areas, where you’ll find invertebrate communities dominated by mayflies, stoneflies and caddisflies. Protecting the streamside vegetation (maintain the riparian area as is) may be the best stream management tactic. There may be no need for expensive riparian planting.

If you or your community group wish to protect such high quality streams from inappropriate development, you may need to watch out for development proposals to clear streamside vegetation, divert or pipe the stream, create a pond in the stream channel, or discharge wastewater or stormwater to the stream. Development proposals that may significantly affect stream resources should go through a resource consent application process, which gives you the opportunity to make a submission where you can outline the current natural stream values, and your concerns that such values be protected.