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Opening Section

Foreword and Acknowledgements

Introduction

Part I: The Framework for Monitoring Recreational Water Quality

Part II: Guidelines for Recreational Water Quality

Part III: Explanatory Notes to the Guidelines

Appendices

Further Information

Appendix 4: Case Study - Implementing the Marine and Freshwater Guidelines

Jacobs Estuary – Southland

Environment Southland co-ordinates recreational water-quality monitoring in the Southland region. The following case study focuses on one of 13 marine recreational sites monitored in the region, details the process for developing a grade for the site, and defines the resulting surveillance monitoring regime and responses.

Microbiological Assessment Category (MAC)

Jacobs Estuary has been monitored for at least five years, so there is sufficient data to generate a MAC. Using the Hazen method recommended in the guidelines, the 95th percentile for this site is 99. Repeat or follow-up samples are not included when calculating the MAC.

Referring to the Microbiological Assessment Category Definitions the MAC for Jacobs Estuary is B.

Sanitary Inspection Category

The following table presents the findings after working through the Catchment Assessment Checklist and the resulting Sanitary Inspection Category.

Table I1: Example of completed Catchment Assessment Checklist (PDF 12 KB)

The primary source of potential contaminants to the bathing site in Jacobs Estuary is the Aparima River. The land adjoining the Aparima River has moderately intensive agriculture with an increasing amount of dairy farming in the catchment. This corresponds to a ‘moderate’ risk. Stormwater drains enter Jacobs Estuary, but these are distant from the bathing sites and were not considered to be significant influences. A sewage overflow was discovered on the western side of Jacobs Estuary in 2001, but this did not appear to influence monitoring results and has since been rectified.

The Regional Council confirmed its catchment assessment of the site with the relevant territorial local authority and the Medical Officer of Health. The resulting Sanitary Inspection Category (moderate) was referenced from the Sanitary Inspection Flowchart.

Suitability for Recreation Grade

The suitability for recreation of this marine bathing water site was determined by integrating the site’s Sanitary Inspection Category with the site’s Microbial Assessment Category according to the Suitability for Recreation Grade matrix. The resulting grade for this site is Good.

The factors that contributed to the SFRG for this site can be summarised as follows.

Boyes Beach, Bay of Plenty

Environment Bay of Plenty monitors marine and freshwater recreational areas throughout the Bay of Plenty region. This case study examines a freshwater site graded using these guidelines, including how each component is assessed and brought together to achieve an overall grade for the site.

Microbiological Assessment Category (MAC)

Boyes Beach has been monitored for two years, giving insufficient data to generate a final grade. However, there is sufficient data to generate an interim grade. An interim grade is used primarily for management purposes and must be reviewed annually as new data becomes available, until five years’ data has been collected.

The 95th percentile for this site, generated using the Hazen Method is 207. Therefore the resulting Microbiological Assessment Category is B.

Sanitary Inspection Category

The results of the catchment assessment are summarised in the following table.

Table I2: Example of a completed Catchment Assessment Checklist (PDF 14 KB)

The primary source of potential contamination for Boyes Beach is septic tanks. In addition to the residential on-site disposal systems there is a toilet block to the rear of the beach, which is another source of faecal contamination, particularly during the holiday season when the area experiences seasonal population growth.

The land surrounding Boyes Beach is a mixture of low-density urban and low-intensity agriculture, including beef, deer and sheep. Stock have unrestricted access to waterways that discharge onto the beach, although these are not considered significant impacts due to low stock densities. There is also some forest area around the lake with the potential for run-off from feral animals. However, this was also not considered a significant source of faecal contamination.

Using the Sanitary Inspection Flow Chart for Freshwater Sites, the Sanitary Inspection Category (SIC) for Boyes Beach is Very High.

Suitability for Recreation Grade

The Suitability for Recreation Grade (SFRG) for this site is determined by integrating the site’s Sanitary Inspection Category and Microbiological Assessment Category according to the Suitability for Recreation Grade Matrix for Freshwater. The resulting grade for this site is Follow Up. This is due to the disagreement between the MAC and the SIC.

Investigation of both the MAC and SIC is recommended. The grade for this site is also interim as there are fewer than 100 data points and less than five years’ data. This is likely to be the cause of the disagreement between the MAC and the SIC also.

Factors that contributed to the SFRG for this site can be summarised as follows.