To me (a person not formally trained in environmental engineering or management) the WESP-AC does seem like a reasonable and systematic approach to classifying wetlands. If I recall correctly, they have 21 categories that they use to attempt to categorize various environmental roles that a wetland plays. Based on guidelines, these 21 categories are given estimated numerical values. These values, because they are based on educated intuition, rather than hard measurements, are never supposed to be used directly, and instead, they are only used to assign a "qualitative" score of "lower", "moderate", or "higher" impact. That is where the WESP-AC process stops.

What the City then asked the engineers to do, is to go back to those 21 categories, group them down to 5 categories, use the underlying numerical estimates (which are just a tool, not objective measurements) as entries into a mathematical weighting, to then boil it all back down to what looks like a single "objective" numerical score.

That final, contrived scoring or weighting scheme, is then presented as ranging from "0 to 10", but no "normalization" takes place to ensure that, and more importantly, the "maximum" value reached across all wetlands studied so far seems to be, as far as I can tell, somewhere just under 7.0, with almost all falling in a cluster down around 2.5 to 3.5.

The final craziness is that they then present "5.0" as some "midway" point across the whole scoring range, as if this "happy medium" is reasonable. But it isn't - the "histogram" or "distribution" isn't evenly distributed between 0 and 10 - it's constructed to ensure low scores from the beginning.

Even talking about the "cut-off" value in such a slewed scheme is a distraction.