The Puget Sound is a complex estuarine system within the Salish Sea, fed
by both high salinity water from the Pacific Ocean and freshwater from a
number of rivers. The Snohomish River is one of the largest of these
freshwater inputs, transporting freshwater from the Skykomish and
Snoqualmie rivers to Port Gardner Bay off the coast of Everett. At its
mouth, the higher density salt water from the Puget Sound intrudes into
the freshwater, forming a salt wedge that causes a highly stratified
water column which rapidly changes with the tidal cycle. In this
stratified water column, little mixing occurs between the different
layers of the water, resulting in a lack of nutrients near the surface.
This study aims to quantify the amount of mixing occurring at this
location in relation to tidal patterns and season and analyze the effect
varying levels of mixing have on related chemical properties. This
research is being conducted at the Ocean Research College Academy
(ORCA), a dual enrollment program through Everett Community College. In
cooperation with Gravity Marine Consulting and the Port of Everett, ORCA
has permanently moored a SeaBird CTD 3 meters below the surface in the
mouth of the Snohomish River. The CTD captures temperature, salinity,
chlorophyll, turbidity, and dissolved oxygen measurements at 30-minute
intervals. Velocities in 3-dimensions are recorded by a Nortek Aquadopp.
This study will define the characteristics of the salt wedge in relation
to temperature and salinity and then look at its influence on
chlorophyll and turbidity levels.