% 1070 words
% Explain how you would identify the significant effects. Discuss
% any difficulties in determining the significance of effects in EIA

\section{Significance}

The process of impact assessment is conceptually open-ended. As one of
its major goals is to aid a decision-making process, however, each
step in the assessment must be completed within a given time
frame. Hence, limits are imposed on the level of detail, the length of
the time period for which impacts can be assessed at the expected
level of detail, and the number of interactions that can reasonably be
considered.  To set these limits, judgments must be made on how
significant each potential impact is, a decision on how much detail
and how much effort in avoiding or mitigating the impact is
appropriate, and whether the residual impact is insignificant enough
to be acceptable.  These judgments are crucially guided by the
practitioners' own values and the values they consider in the
evaluation process \parencite{lawrence}.  As the determination of
significance is inherently subjective, it should not be an activity
performed only by experts and with a claim to objectivity, but should
aim to be a collaborative procedure guided by reasoned
discourse \parencite{lawrence-approach}.

According to \textcite{lawrence-approach}, the approach to determining
impact significance is usually ``limited to ad hoc and inconsistent
judgments with reasons and/or to the staged application of thresholds
and/or criteria.''  The Resource Management Act 1991 does not
prescribe a process for the assessment of significant effects. As all
major projects require resource consents, however, impact significance
is, in practice, reflected by the management plans and established by
resource consent decisions of regional and territorial councils. The
Ministry for the Environment bemoans that a ``lack of clarity and
certainty in some regional plans (eg, a lack of enforceable limits)
has led to issues being decided consent by consent and often
re-litigated'', resulting in ``decision-making processes [that] are
litigious, resource-consuming and create
uncertainty'' \parencite[p. 18][]{freshwater-reform}.

Since the National Policy Statement for Freshwater Management (2011)
the ``national values of fresh water'' have been made explicit, but
their postulation does not give rise to a guideline by which the
significance of activities affecting these values could be
determined. For example, the statement made in the NPSFM that water is
valued for ``cleaning, dilution and disposal of waste'' conflicts with
the statement about respecting water's intrinsic values such as ``the
natural conditions of fresh water, free from biological or chemical
alterations resulting from human activity'' \parencite{nps}.
Resolving this ambiguity, the NPSFM intends a limits-based regime to
be established where regional councils are expected to collaborate
with the community to translate individual values and freshwater
objectives into enforcable limits for individual
waterbodies \parencite[][p. 14]{npsfm-guide}.  The implementation and
enforcement of this National Policy Statement---and pending its
implementation, decisions relating to the significance of project
impacts on the environment---crucially depend on a sound information
base derived from regular monitoring.  The National River Water
Quality Network enables the measurement of various water quality
indicators (e.g. temperature, dissolved oxygen, turbidity, nutrients
etc.) at 77 sites and has been used to measure nation-wide water
quality trends \parencite{nrwqn}. In total there are about 600
monitoring sites \parencite{water-quality}.

%According to the \emph{Environment New Zealand 2007} report ... % say something about water quality trends?

Following a limits-based approach and with the help of a monitoring
network, it would be practical to impose absolute limits for a variety
of water health indicators. Whether a residual impact on the physical
environment is significant or not then is a matter of setting measured
water trends against the expected level of the impacts of a proposed
activity.

In the case of the planned dairy factory, the significance of the
impact of discharging warm water into the river not only depends on
the absolute value of the temperature difference between wastewater
and river water, but also on the cumulative temperature increase due
to human activity reflected in the mean temperature of the affected
body of water. Case studies can be used to estimate the magnitude of
the impact. If the limit on water temperature would be exceeded by the
plant's wastewaster discharge, the impact would be rated as
significant and in need of mitigation to avoid significant effects on
the aquatic ecosystem. The same approach is applicable for any impact
that affects quantifiable environmental properties, such as the
release of organic and inorganic compunds, or the contamination with
residual antibiotics and pesticides.  According to the description,
the river is already used as a sink for the wastewater of another
dairy factory; dairy farming is said to have expanded in this area,
indicating that the inflow of organic and inorganic components from
farm effluent and non-point sources has also increased. It is likely
that under these circumstances, the cumulative impacts of wastewater
discharge would be deemed significant.


(third part of lawrence): important to assess significance of
*positive effects* to see if they are worth the negative impacts.

- positive effects can be quantified, but it is not clear how to weigh
  potential economic benefits against expected negative impacts on the
  biophysical environment without imposing market norms on intrinsic
  ecosystem values.

- other impacts cannot easily be quanitifed

%  - talk about drawbacks mentioned in \textcite{lawrence-approach}
%      \begin{quote}
%        The collaborative approach is viewed as too quickly equating
%        public concerns and issues with impact significance, at the expense of
%        other sources of insight and knowledge.
%      \end{quote}


- significant impacts:
  - likelihood
  - effects that affect sensitive parameters