I believe there is much misunderstanding about the nature and value of wetland inventories and mapping. The concept of complete and accurate wetland maps is wonderful; the liklihood of ever achieving that ideal is very remote. I have delineated wetlands, on the ground, for many years and have compared wetland maps to reality and been very disappointed. To create statewide wetland maps that are reliable - and anything less is a waste of time - will require a large army of well-trained people with very accurate GPSs and several decades to do their work. (How long have we been working on soil surveys? Wetland delineations are much finer work.) I would love to be part of that army, but I don't have anything strong enough to put in my hookah that could make me believe any government is willing to make such a commitment.
The wetland maps that have recently been produced by the DEQ are amalgamations of the information already available in county soil surveys, National Wetland Inventory maps, and the old DNR MIRIS maps. Soil surveys are notoriously inconsistent from county to county and at their very best have a spatial resolution of about 2 acres. MIRIS wetland maps are junk. The NWI maps are the most accurate, are not the result of on-site delineations, and are 1:24,000 gross generalizations of wetland occurance. An area mapped as wetland typically has a fairly high probability of being wetland, but areas not mapped as wetland are terra incognita.
Part 303, Wetlands Protection would be better law if all reference to wetland inventories - for locals and the state - were struck. Read the last three sentences of section 30308 and you will understand the problem with inventories as they are actually performed: you can not rely on the information in them, they have no absolute authority, and are therefore open to challenge in every instance. So where does that leave us? Back to site by site analysis of wetland resources, right where we are now.
My belief is that many of the people who are pushing for completion of an inventory know that many wetlands will be unaccounted for, that any upland mapped as wetland can easily be taken out of the inventory by challenge, that an inventory will replace ground truth, and that the inventory will ultimately result in a more comfortable climate for developers. I see an inventory replacing people who have wetland expertise.