As promised in our cover story this week, this morning a coalition of businesses that could be on the hook for  a Portland Harbor cleanup released its study of possible cleanups in the Willamette River.

The Lower Willamette Group's feasibility study took more than 10 years and cost $96 million—including more than $24 million from the city.

It outlines seven options for a harbor cleanup (with five of those divided into sub-options, just to make it more complicated). The most expensive is budgeted at $1.1 to $1.7 billion. The cheapest is doing nothing.

Now the Environmental Protection Agency starts poring over the data, deciding whether further drafts are needed, or whether it can accept one of the proposed cleanup scenarios.

You can download an executive summary of the study here.

But first, let's address the five most important things the study says.

1. No matter what option EPA chooses, it's likely there will be plenty of dredging work between the Steel Bridge and Fremont Bridge. Contaminant levels are so high there that all options call for cleanup work in this area.

2. The plans lean more toward dredging the chemicals out than capping them under mud and rocks. In the most limited cleanup, the companies would dredge 3.2 times as many acres of sediment as they capped. In the most expansive, they'd dredge 8 times more acres than they'd cap.

3. How much sediment is EPA thinking about moving or burying? The plans range from cleaning 49 acres of riverbed to 391 acres. Put another way, the responsible companies could be forced to dredge as few as 198,000 cubic yards of sediment, or as many as 6.1 million cubic yards.

4. What's the probable cost of the clean up? As little as $169 million to as much as $1.7 billion. That's way less than the $2.2 billion an earlier industry-commissioned study warned the project could cost. The three options the Lower Willamette Group strongly recommends in the study are on the low end of the spectrum, ranging in cost from $169 million to $398 million. So those are the numbers we're probably talking about in real life.

5. The disparity between the possible cleanups becomes most stark when viewed in terms of how long they'll take. The smallest cleanup would take just two years, and even a mid-range effort could be done in six. The largest one would take 28 years.