This report has been prepared as a continuation of the Northland Regional Council's (the Council) State of the Environment Monitoring Programme. It presents the results from habitat assessment work undertaken in 2008 and 2010, along with an initial analysis of data collected over the last five years, to identify any emerging trends in habitat quality or channel stability at 35 River Water Quality Monitoring Network sites. Data from the 2007 round of monitoring is available in a separate report entitled Northland Habitat Assessment 2007.
River habitat assessments are undertaken by the Council in order to monitor stream health and stability and track changes over time in Northland's rivers. They also provide valuable information on the state of Northland's riparian environment and the information can aid in the interpretation of both water quality and macroinvertebrate data collected by the Council at the same sites.
River habitat quality is a reflection of both natural and man-made influences. ‘Pristine' river sites generally have good stream health and are characterised by natural factors, such as stream geology, gradient and physico-chemical properties. Impacted river sites (sites located in catchments that drain intensive land-use) tend to have poorer stream health and are influenced more by surrounding land-use and human activity.
Channel stability is not necessarily related to stream health, although it can influence it. Channel stability depends on physical characteristics, such as bank and substrate type, the flow regime and riparian vegetation, as well as human activity, such as surrounding land-use and channel alteration. It is also influenced by climate, in particular rainfall and storm events, and so can be naturally variable.
River ecosystems are an important social, cultural, economic and environmental resource. Monitoring these environments allows us to quantify the resource, identify river systems that require attention and focus resources into these areas.
Kerikeri River at Stone Store, upstream view.