Low Impact Drain Maintenance in the Waimakariri District

In pre-European times the eastern part of the Waimakariri District from the coast to approximately 15 km inland was predominantly swamp land. Early settlers set about draining these swamps forming the majority of drainage network that exists today. Old style cleaning practices resulted in degradation of waterways and little consideration was given to sediment control or biodiversity values. In recent years respect for in-stream biodiversity and awareness of the benefits of excluding stock from waterways has become common and some waterways have been naturalised. Along with the benefits of increased biodiversity and aesthetics these waterways require less maintenance and in many cases the waterway looks after itself. In 2008 Council staff in collaboration with the drainage maintenance contractor started to experiment with the use of a rake instead of the traditional silt / weed bucket to clean waterways. This has proved effective in removing the majority of weed and allowing in-stream fauna to migrate back into the waterway.

This paper provides examples of low-maintenance waterways and compares the effects of low impact cleaning versus traditional cleaning methods.