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Objectives define an endpoint of concern and the
direction of change that is preferred - all else being equal,
more is better than less, or vice versa. In contrast to targets
or goals, objectives as used in SDM do not define specific
quantitative thresholds that must be achieved. They are not
analogous to regulatory standards for water or air quality that
establish fixed targets, (e.g., BC's "provincial water
quality objectives").
In a typical target-setting process, targets are
established first (e.g., reduce emissions by 50%, increase
salmon habitat by 50%). Yet at the time of setting the target,
little or nothing is known about how the target will be achieved
(the alternatives), or what it will cost, either financially or
with respect to other objectives (the trade-offs).
Target-setting is suitable when:
a) there exists a clear threshold of effects -
i.e., below some threshold we are safe and above it we are
not;
or
b) it has been shown that there exist many low
cost, no-regrets actions to achieve the target.
However, there
are relatively few situations where one of these conditions
holds. In most cases, biological or human health effects lie on
a continuum, true thresholds either don't exist or are unknown,
and low-cost no regrets actions have already been
undertaken.
In the SDM process, the implications of
different targets are explored through evaluation criteria and
alternatives, so that the trade-offs are exposed before a target
is adopted.
Suppose for example, that a decision process is
underway for establishing industrial discharge permits in a
watershed. For one contaminant of concern, suppose that there
exists a widely cited "no observed adverse effects
level" or NOAEL, and that this level is currently regularly
exceeded in the watershed. An SDM process in this case could
establish an evaluation criterion for the "number of
exceedences per year of the NOAEL". The NOAEL is not set as
a target that must be achieved at all cost, but it is recognized
as a significant benchmark, and so it is useful to report the
expected consequences of the alternatives with direct reference
to this benchmark. The SDM process can then go on to test the
implications of different targets through alternatives. One
alternative may be designed to allow zero exceedences, another
up to five per year, and another up to twenty per year. One can
imagine that these alternatives would involve different permit
levels or technology standards for various dischargers in the
watershed, and that each alternative would have different
implementation costs and possibly different performance with
respect to other contaminants and hence differences in other
environmental effects. The consequence table should expose these
trade-offs. Decision makers can then select the alternative with
the most desirable balance across the objectives, which may or
may not be one that allows occasional exceedence of the NOAEL.
Next: Evaluation
Criteria>> |
SDM Objectives do not define specific quantitative
thresholds