Bunz Stream spring

The survey included

• water quality parameters
• habitat (including riparian margins)
• bethnic macroinvertebrates (aquatic animals without backbones that live on the bottom of water bodies)
• fish.

Bunz Spring has a “moderate” overall aquatic ecological value based on methodology that has been modified for freshwater environments.

Water quality in the spring is generally good and parameter measurements did not throw up anything unexpected. Results were either in line with other surface water monitoring nearby (eg nitrates) or characteristic of groundwater (eg dissolved oxygen). That is to say, the water quality in the spring is dependent on the quality of the groundwater which feeds it which in turn reflects the recharge source (Waimakariri River with a Port Hills runoff component), aquifer geology and land use practices (which enable and/or provide contaminant contributions).

Habitat and riparian conditions were moderate in general, with no bank erosion and with diverse vegetation. However, the canopy cover was minimal (but showing good potential for greater coverage) and fine sediment cover is high (as is typical in a groundwater-fed freshwater spring). Growth of submerged aquatic plants is steady, with high nutrient levels and low canopy cover – and subject to regular channel maintenance.

The benthic macroinvertebrate community (MCI and QMCI) scores were “poor”, with low overall diversity. Regular channel disturbance is a factor in these scores.

Four fish species (including the at-risk inanga Galaxias maculatus) were found, all common to lowland streams, suggesting that there is good connectivity to the sea.