Principal Reasons and Explanations

The Concise Oxford Dictionary defines a 'reason' as being "a cause, explanation, or justification" or alternatively a "good or obvious cause to do something". 'Explain' means "to make (something) clear by describing it in more detail" or to "give a reason or justification". There is some overlap between the terms 'reason' and 'explain'. Consequently many first-generation RMA plans grouped explanations and reasons together.

The inclusion of principal reasons in the plan is at the discretion of the council but ss67(2)(c) and 75(2)(c) limits them to being "principal reasons for adopting policies and methods".

Sections 67(2)(h) and 75(2)(h) allow a council, at its discretion, to include any other information required for the purpose of the council's functions, power and duties under the RMA.

Should reasons and explanations be included in plans?


  • Reasons and explanations provide additional information to assist understanding of provisions, and how those provisions fit with other plan provisions.
  • They assist in making plan provisions transparent (justifications for the presence of certain provisions are able to be provided).
  • They assist in explaining the links and relationships between policies, including regulatory and non-regulatory approaches.


  • Reasons and explanations add to plan length without being crucial to the operation of the plan (they have no legal effect).
  • They add more material that could be the subject of submissions and appeals (and thereby add cost and time to the plan development process).
  • Similar material can be incorporated into external documents such as s32 reports and guides to the plan.
  • Extensive explanations can confuse rather than assist the plan reader through using different words or suggesting a meaning that does not match that of the ordinary meaning of the words in the provision that it seeks to explain.
  • They may not adequately explain all of the details and reasoning behind policies without adding considerably to plan bulk.

Practice in writing reasons and explanations


When preparing reasons it is good practice to:

  • keep the style of reasons consistent throughout the plan
  • (if the reasons for one provision are exactly the same as those for another provision) use the same wording in those explanations and reasons, or combine the reasons if located close together.
  • write reasons from the perspective of:
    • how objectives manage the environmental issues of the region or district and the purpose of the RMA (i.e. achieve sustainable management and avoid, remedy or mitigate effects)
    • how policies and methods meet the objectives of the plan, manage effects, or the intent of the RMA
  • keep reasons relatively short (more detail can be contained in the s32 report if necessary
  • ensure there is a logical sequence between reasons (no non-sequiturs).


When preparing explanations it is good practice to:

  • use explanations for rules only where necessary (draft rules so the meaning can be derived from the ordinary meaning of the words in the rule itself; explanations are then not necessary)
  • ask:
    • Do the provisions need explanation or is the meaning self-evident?
    • Does the proposed explanation add to the understanding of the provision (or its context) or hinder it? (Testing the proposed wording with another person who has consent processing experience could assist in this.)
  • keep the style of explanations consistent throughout the plan
  • (if the explanations for one provision are exactly the same as those for another provision) use the same wording in those explanations and reasons or cross-reference to a 'common explanation'
  • use diagrams to support explanations where provisions have a geographical or spatial element that is difficult to describe.

Explanations should not:

  • contain material that should be in the provisions they seek to explain nor repeat verbatim content of the provisions they seek to explain
  • paraphrase or attempt to reword the provisions they explain in a way that may give rise to a different interpretation of those provisions.

Examples (District Plan)

Principal reasons: Policies 5.5.1 to 5.5.4

The instability of slopes in the Waipopo hill country means that excavation and infilling associated with establishing building platforms and roads can contribute to slips, increased erosion or subsidence. Restrictions on the location of building sites are the most effective means to avoid adverse effects in this area but engineering solutions that meet the intent of objective 5.5 may also assist.

Principal reason: Rule

The protection of historic heritage is a matter of national importance under section 6(f) of the Resource Management Act 1991. Modification of historic sites and buildings to allow other uses can destroy the heritage values of those sites and buildings. The resource consent process allows effects to be assessed and managed.

Explanation: Rule

Large numbers of big signs can adversely affect the visual appearance of heritage areas. This rule sets standards managing the number, height and area of signs on buildings or fences in the Watane Heritage Area with the consents processed used to evaluate individual standards exceeding the standards. Signage on footpaths in the Watane Heritage Area is managed through the Whatsup District Council Sign By-law (1997).

Explanation: Rule

Rule is designed to provide for the safety of aircraft flying in and out of Whatamata Airport by providing a corridor of airspace in line with the ends of the runway that is free of obstacles. The rule prescribes a sloping maximum height plane (Shown to scale in map G6) that overrides any less stringent maximum building or structure height rules contained in this plan. Outside the sloping height plane, the height limits particular to the zone apply.

Safety of Aircraft

Examples (Regional Plan)

Principal reasons: Policies 5.5.1 to 5.5.4

Policies 5.5.1 to 5.5.4 manage the discharge of contaminants into air (see objective 5.5) by focussing on the origin of discharges and their location. It is difficult to control or mitigate the scale and distribution of effects of airborne contaminants once they are released so management is primarily focussed around avoiding emissions of contaminants at their source. As it is not possible to avoid the discharge of contaminants in every case, policies 5.5.3 and 5.5.4 provide guidance on the type and degree of mitigation that may be considered where avoidance is unwarranted or impractical.

Principal reason: Rule

Policy 6.6.7 of the Erehwon Regional Policy Statement requires that plans recognise and provide for sea level rise as an effect of climate change. The best current estimates of possible sea level rise indicate a rise of 0.2 metres by 2030 and 0.66 metres by 2100. The figure of 0.5 is used in the policies and rules of this plan as an estimate of the sea level rise within the average lifetime of structures being built in the Erehwon coastal environment.

Explanation: Policy 10.8.9.

The soil and water bodies of the Waipopo hill country are close to their assimilative capacity. Policy 10.8.9 and associated rules to limit further, cumulative wastewater and effluent discharges to avoid that assimilative capacity being exceeded. Rules in the Whatsup District Plan complement policy 10.8.9 by requiring all dwellings built on residential or rural residential zoned to have access to, and be connected to, a reticulated sewerage system.

Explanation: Rule

The aerial application of fertilisers is a commonly used management technique and may be the only practical means of distributing fertilisers effectively in some areas. Provided that the specified criteria are met, effects will be minimal. Applicators accredited by the Agricultural Education Trust are required to comply with the Agricultural User's Code of Practice which places additional safety restrictions on this type of application.