Environmental watchdogs are denouncing the the plan unveiled by the U.S. Environmental Protection Agency yesterday to to clean up the Superfund site in the Portland Harbor, saying it treats the pollution at the bottom of the Willamette River by expecting it to naturally drift away.

They want more time to make their case—and are pressuring the EPA for at least four months of public comment.

The plan, which is estimated to cost $750 million, would require 150 acres of the Willamette River bottom to be dredged, or 1.8 million cubic yards, to remove polluted sediment.

The number is less than what's in the plan that the National Remedy Review Board recommended in December, which would have required the dredging of 2.2 million cubic yards.

The EPA's plan is the latest step in forcing companies along Portland's industrial harbor to pay for the decades of pollution sitting in the Willamette riverbed—toxic chemicals that are consumed by bottom-feeding fish, and can be passed along to people who eat those fish.

Under the proposal, 1,876 acres of the harbor would rely on "monitored natural recovery," a method which mostly entails monitoring natural sediment flow.

That idea was met with praise from the Lower Willamette Group, a coalition of companies who own property along the Portland Harbor and will have to pay for the cleanup.

"This complex river system can be cleaned up efficiently and within a reasonable time by focusing on areas where contaminant levels present the greatest potential risk to humans, fish and wildlife," says Barbara Quinn, spokeswoman for the Lower Willamette Group.

But Travis Williams, executive director of Willamette Riverkeeper, says "natural recovery" is a misguided approach. "That's really the do-nothing answer: You monitor it and hope it does its job," Williams says.

EPA Regional Administrator Dennis McLerran says that the EPA is currently set on reaching a an agreement on the proposal by the end of the year, and that there would be a 60-day public comment period starting on June 9. However, he said that the EPA will accept proposals for extending the comment period.

Williams says that a 60-day comment period is much less than is needed to fully absorb the public's input, noting that the EPA allowed 120 days of public comments for the proposal to cleanup the Lower Duwamish Waterway in Washington.

Ultimately, Williams says, the comment period will be crucial in developing a more ambitious cleanup plan: "They seem to be approaching this only on cost. They are providing a very weak draft plan, and my hope is that over the next 60 days people will chime in and let the EPA that they want a more robust effort."

To understand the perimeters of this political struggle, which has barely changed in four years, check out this WW cover story from 2012.