Publication Summary

This study examines the environmental health of South Puget Sound in terms of dissolved oxygen and nutrient (nitrogen and phosphorus) levels. Increased nutrient levels from population growth can cause lower dissolved oxygen levels, reduce water clarity, increase toxic algae blooms and unsightly algae mats and scums, and change species distribution.

The study evaluates the sensitivity of the Sound in two ways: 1) field observations and experimental measurements and 2) development of a mathematical model. The study concluded that South Puget Sound is sensitive to nutrient addition and that Case, Carr, and Budd inlets have the lowest dissolved oxygen levels within South Puget Sound.

Increasing development around South Puget Sound, defined as the basin south of The Narrows near Tacoma, may adversely affect marine water quality through elevated point and nonpoint source loading of nutrients. Although individual sources may not have a measurable influence, their combined impact could lead to significant water quality degradation, such as reduced dissolved oxygen concentrations, reduced water clarity, altered species composition, and formation of algal scums.

South Puget Sound′s complex morphology contributes to slow flushing rates, which limits the ability of the basin to dilute and exchange with the Pacific Ocean. Several inlets have high productivity and low near-bottom dissolved oxygen. Many studies have concluded that South Sound is particularly susceptible to water quality problems. South Puget Sound marine waterbody segments have been identified as impaired through the federal Clean Water Act Section 303(d) list for dissolved oxygen, fecal coliform bacteria, and other variables.

The South Puget Sound Water Quality Study offers the opportunity to quantitatively assess existing and potential future water quality. It is divided into two phases: