Report 3 - Executive Summary

Prioritisation Methodology

This document, which was prepared for EcoWater by Montgomery Watson and Project Management, outlines a methodology for prioritising stormwater catchments for the purpose of managing a wide range of stormwater issues in a focussed and integrated manner.

It is divided into three major sections:

• Part A - Introduction and Rationale; which outlines context and the reasons for prioritising stormwater catchments
• Part B - Prioritisation Methodology Statement; which details a methodology and the steps required to carry out prioritisation of stormwater catchments
• Part C - Prioritisation Methodology Application: System and Process; which documents Waitakere City Council's application of the methodology and contains the various outputs of each step of the prioritisation process, including the Waitakere City Catchment priorities

Part A looks at the combined efforts of territorial authorities and the Auckland Regional Council in producing an urban stormwater strategy to improve stormwater management in urban areas. It also looks at Waitakere City Council's holistic approach and philosophy for developing a stormwater strategy, which fits into the wider context of strategic planning for the City.

The rationale for prioritising stormwater catchments is explored, and why territorial authorities should ensure that this approach is used when preparing and implementing strategic, asset and district planning.

Part B provides an example of the steps required to carry out stormwater prioritisation in any given locality. It shows how to get started, i.e. developing and documenting a 'Terms of Reference', creating a catchment plan, carrying out preliminary information gathering and the importance of holding stakeholder workshops.

Catchment issues are covered from assessing land use activities, topographical and geological characteristics, identifying issues and sub-issues within a given study area, to gathering and recording specific information and data for later scoring. Assessing and recording the receiving environment condition of both freshwater and marine areas are covered in some depth.

Receiving Environment community values, could cover the assessment of recreational activities, food gathering, cultural and historic considerations, the aesthetics and locality of an area and any commercial activities which may affect an areas value.

A methodology for catchment assessment is described, which rates catchment issues, receiving environment condition and receiving environment community values from extremely high to nil. This is followed by a catchment ranking process. These rankings are then utilised to build scenarios, which encompass the critical issues that require addressing. Local authority politicians are then engaged in the process to determine the preferred scenarios, and hence the catchment priorities.

Part C looks at how Waitakere City prioritised its 28 stormwater catchments, using the methodology outlined in Part B.

An agenda item was presented to Waitakere City Council outlining the stormwater implementation scenarios and associated information. The scenarios involved addressing:

• public health, development and safety issues; and then, either:
• remaining flooding priorities: giving priority to solving the City's flooding problems over the next ten years or so; or
• high quality receiving environment catchments: giving priority to protecting the City's catchments with existing relatively high quality receiving environment from further degradation; or
• low quality receiving environment catchments: giving priority to cleaning up catchments with relatively degraded receiving environments; or
• arterial routes: undertaking work in those catchments that include the City's high use roads.

Report 3 - Full Version

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