The Army Corps of Engineers will restore some one thousand acres of shallow-water habit for salmon at the mouth of the Columbia River as part of its channel-deepening project in the river, the National Marine Fisheries Service said today.

In a biological opinion to be released later this week, the fisheries service said the Corps had agreed that it would offset any potential harm that might come to federally protected salmon during an expected two-year period of river dredging by creating habitat along the banks of the river west of Portland. The Corps is also committed to speeding up another effort to repair the effects of decades of development elsewhere in the river-mouth estuary.

The fisheries service is responsible for protecting salmon and steelhead listed under the Endangered Species Act.

"When this habitat restoration project is completed," said William Stelle, head of the fisheries service's Northwest regional office in Seattle, "the Lower Columbia will be more salmon friendly than it was before the dredging started. That's good news for all the fish that spend time at the river's mouth."

As the navigable channel from the river's mouth to Portland has been repeatedly deepened over the years to accommodate larger and larger vessels, the river mouth's ecosystem has changed, according to fishery biologists. These changes, especially the intrusion of a wedge of denser salt water from the Pacific into the river's freshwater mouth, have resulted in changes to the food chain and habitat that have not been good for salmon.

The plan, laid out in the fisheries service biological opinion, is for the Corps to restore lost habitat along parts of the Lower Columbia by breaching dikes, opening up long-closed channels and removing some fill and bulkheads. The initial result will be the creation of about 1,000 acres of new habitat in shallow water, exactly the kind of system that provides food and shelter for young salmon preparing to make the adjustment for their multi-year sojourn in the ocean.

In addition, the fisheries service said, the biological opinion calls for an additional 3,000 acres in other parts of the Lower Columbia to be restored, half by 2010 and the rest by 2020.

Biologists with the fisheries service will monitor changes to the river's ecosystem as dredging proceeds and make adjustments to the operation as it progresses.

The project is expected to remove about 23 million cubic yards of river bottom from various parts of the 100-mile long channel as it is deepened to 43 feet from the current 40 feet. The deeper channel will allow larger vessels to use Portland and several other Lower Columbia River ports.

Thirteen populations of salmon and steelhead, protected under the Endangered Species Act, pass in and out of the Lower Columbia every year.