Physical environment

Overview

The Puget Sound ecosystem is shaped by its physical environment. This article looks at Puget Sound's geologic history as well as dynamic factors such as the flow of its rivers and currents.

Puget Sound basins. The oceanographer’s definition of Puget Sound is limited to the following marine basins: Hood Canal, Main Basin (Admiralty Inlet and the Central Basin), South Basin, and Whidbey Basin. Map: Kris Symer. Data source: WDFW.

Related Articles

Complex physical processes such as hydrology, nutrient cycling, and sediment transport are linked to water circulation patterns in Puget Sound. 

For close to 100 years, Seattle's Ballard Locks has been one of the region's busiest waterways, drawing major boat traffic along with millions of tourists. But as it prepares to celebrate its centennial, the aged structure is also drawing the concern of engineers. They worry that an earthquake could cause the locks to fail, draining massive amounts of water from Lake Washington and Lake Union. In some scenarios, the two lakes could drop by as much as 20 feet, stranding boats, disabling bridges and causing big problems for salmon restoration.

Chinook, coho and sockeye salmon, along with steelhead trout, live in the Lake Washington watershed and navigate a treacherous route through the Ballard Locks on their way to Puget Sound.

This overview discusses the processes that control ocean and climate characteristics. Topics include atmospheric forcing, precipitation patterns, oscillation trends, coastal upwelling, and climate change.

The boundaries of Puget Sound and the Salish Sea are not always consistently defined by scientists and government agencies. This article clarifies the distinctions between oceanographic and watershed-based definitions of these geographic areas. 

Land cover conversion through human development was listed as a leading cause of ecosystem decline in the 2014 Puget Sound Pressures Assessment, a document supported by the Environmental Protection Agency and prepared by more than 60 of the region's scientists.