Biomonitoring and compliance : the use of macroinvertebrate monitoring by regional authorities to monitor the exercise of discharge permits

Abstract

Under the Resource Management Act 1991, regional authorities are required to monitor the exercise of resource consents within their region. The methods of monitoring resource consents will depend on the type of activity to which the consent relates. For discharges into rivers and streams, a method that can be employed is to monitor the state of macro invertebrate communities, above and below the discharge, to determine the compliance status and/or impact of the discharge on aquatic life.

The use of macroinvertebrate monitoring by regional councils to determine the impact of discharge permits has not been thoroughly investigated, neither are there guidelines as to when this type of monitoring is appropriate. Therefore, the aim of this research was to examine the use of macroinvertebrate monitoring for assessing the exercise of discharge permits by regional authorities. A combination of a literature review and a survey of regional authorities were used to investigate when this type of monitoring is appropriate, the extent to which this monitoring has been employed, and the factors that determine whether this type of monitoring is undertaken.

Results indicated that most regional authorities (both regional and unitary councils) have required macroinvertebrate surveys as a condition on discharge permits at some stage, although the extent and quality of this type of monitoring varies between councils. There are no hard and fast rules as to when macroinvertebrate monitoring is appropriate. Whether or not macro invertebrate monitoring is undertaken is a case-by-case decision that depends on two key factors: (a) the likelihood of a significant adverse effect on the aquatic ecology, and (b) whether macroinvertebrate monitoring is appropriate in this situation. Four themes were identified in relation to these factors: the nature of the receiving environment, the characteristics of the discharge, what is reasonable for the consent holder, and what is reasonable for the consent authority.

This research identified important issues that regional authorities should consider before requiring or undertaking this type of monitoring. This included: the process of deciding whether a macroinvertebrate monitoring condition is required; the use of consultants; how the monitoring condition should be worded; and how results of the monitoring should be reviewed. Recommendations in relation to these issues have been made in order to improve the practices of regional authorities.