By 1900, the mouth of the Columbia River was not quite as dangerous for boats to enter. In the early 20th century, the Army Corps of Engineers dredged the channel at the mouth of the river, and built long and deep jetties out into the ocean. This underwater engineering gave some protection to river entrance by confining the tidal flow, and slowing the build-up of sand deposits from upstream. Ships entered more easily, and inland river ports grew, such as those in Portland and Kennewick.

Since 1999, some controversy has surrounded the Army Corps’ plans to deepen the ship channel. The Army Corps, federal agencies, scientists and others dispute the likely impact of deeper dredging on critical salmon habitat in the delicate estuary system.