Patterns of dissolved oxygen in South Sound:
At depth, oxygen levels follow seasonal patterns, and they are lowest at this time of year. Shallow inlet oxygen patterns are much more complex. Water stagnates during neap tides, and dissolved oxygen can be lower then.
Mindy Roberts does water quality modeling for Department of Ecology. She is sorting out human versus natural drivers on oxygen levels in South Sound, especially nitrogen sources. Marine sources are more influential than rivers. Examples of human influences are wastewater treatment, leaky septic systems, runoff developed areas… Ocean conditions are changing as well.
Our population will increase significantly in the future. South Puget sound is at the end of along conveyor belt of circulation in South Sound. It is very sensitive to increases in human pressures.
Every inlet of Puget Sound has a unique pattern of circulation and oxygen pattern, a unique response to changing conditions.
This is a long term modeling effort. Mindy and her colleagues are looking right now at how to reduce nutrient inputs that affect dissolved oxygen.
North Sound influences South Sound.