Marine Water Quality
The Puget Sound Georgia Basiri Ecosystem Indicators give a glimpse into the health of our ecosystem, which includes
the interactions among seven million people, their health, local economies and a complex system of water, land, plants,
animals and microorganisms. This indicator measures water quality based on seawater density stratification from 1998-
2004 in Puget Sound and 1999-2004 in the Georgia Basin. Seawater density stratification is an indicator of the degree
of mixing within the water column (the water between the surface and the marine floor), its resilience to mixing, and the
iikeiihood that aspects of poor water quality will develop due to human induced pressures. Together, this set of metrics
describes the relative vulnerability of marine waters to water quality problems such as excessive algal blooms and low
dissolved oxygen levels.
Seawater can be layered, similarto the way an oil and
vinegar salad dressing separates. Stratification is a
measure of this layering. But unlike salad dressing,
water density is affected by temperature and salinity:
density increases with decreasing temperature or
increasing salinity. Imagine denser cold and salty water
underlying a warmer and fresher surface layer - the
bigger the density difference between these two layers,
the less likely they are to mix, and water quality prob-
lems can develop. Seawater stratification is character-
ized by its intensity and persistence. Stratification affects
What Is Happening?
The degree of water stratification is labeled in the map at right according to both its
intensity and persistence: strong persistent, strong intermittent, moderate infre-
quent and weak infrequent. In past decades, it appeared as if the marine waters of
Puget Sound and the Georgia Basin had an almost limitless ability to assimilate
the various wastes from our cities, farms and industries. Recent trends, however,
indicate that the natural capacity of these coastal waters to assimilate pollution is
much more limited than we thought, particularly in areas such as Hood Canal,
south Puget Sound, inner Whidbey basin and the central Georgia Basin. In these
areas, as strong stratification has developed and persisted, the respective water
quality has steadily decreased. This trend is the basis forthe indicator's declining
conditions rating. As waters become more stratified, through weather, climate or
circulation changes, they become even more limited in their ability to assimilate
pollution. Where stratification patterns are strong and relatively persistent, we
must do our best to reduce and minimize human impacts on water quality —
otherwise, we risk losing these valuable marine ecosystems.
the overall sensitivity of the water to pollution from humans,
such as sewage, excessive use of fertilizers (nutrients) and
other chemicals from paved land surfaces, and changes in
circulation and the filtering capacity provided by wetlands
and vegetated shorelines. In a way, the intensity and persis-
tence of stratification can tip the balance to favor either
better or worse marine water quality.
fled - e'.rortg,'persistent
Orange strong inlemUtiait
Ye bo* moderate Infrequent
Greer weai Infrequent
Seawater stratification patterns
Puget Sound
Between 1998 and 2004, a series of 46 stations in
greater Puget Sound were monitored monthly for water
quality and density stratification. The majority of the
stations (23) show moderate infrequent stratification.
These are located throughout the Puget Sound and
reflect the strong tidal mixing of the area. Eleven sta-
tions show strong persistent stratification. These are
typically located near river mouths (e.g. Budd Inlet, Com-
mencement Bay, Port Susan, Possession Sound, Skagit
Bay), near river influence (Penn Cove, Saratoga Passage),
or where mixing processes are weak (Hood Canal).
continued
http://www.epa.gov/regionlO/psgb/indicators/

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Marine Water Quality Indicator Summary
October 2006
What Is Happening? continued
Georgia Basin
Between 1999 and 2004, a series of 13 stations, extending from the
mouth of Juan de Fuca Strait up to the northern end of the Strait of
Georgia were visited seasonally. Each year, surveys were taken in
April, June, September and December to capture seasonal varia-
tions.
The majority of the stations show strong persistent stratification due to
the influence of freshwater from the Fraser River. However, stations
located in strong tidally induced mixing areas, such as Boundary Pass,
Rosario Strait, and the northern end of the Strait of Georgia, show
moderate infrequent stratification.
Why Is It Happening?
Factors that influence stratification include: ambient air temperature,
solar radiation, freshwater input from riverflows and precipitation, surface
winds, internal waves, and tidal circulation. Both freshwater (reducing
salinity) and solar radiation (increasing temperature) cause greater density
differences to develop between the warmer, freshersurface layer and the
cold, salty deep waters.
The role of our geography: The waters at the ends of the deep Ijords of
the Puget Sound and Georgia Basin, and in the deep bottom waters
behind shallow underwater mountains (sills), are somewhat isolated
from exchange with incoming Pacific Ocean waters. The implications
are that pollutants, such as fertilizers or toxics, released into these
areas may become entrapped within local areas over relatively long
periods of time.
How Does This Affect Me?
When marine water becomes strongly stratified, it becomes more
vulnerable or sensitive to human impacts and pollution. These impacts
can affect communities and ecosystems in many ways:
•	Low dissolved oxygen impacts: Strong persistent stratification
forms a barrier to mixing and can lead to oxygen declines in the water.
In sensitive marine waters, problems associated with low dissolved
oxygen levels, or "DO," may become more pronounced and directly
affect aquatic life. Low DO levels can kill fish over large areas.
•	Loss of recreation, fishing and wildlife viewing revenues: This
region is very popular for outdoor recreation. Human-caused pollution
can quickly contribute to problems in areas with strong persistent stratifica-
tion. This can include negative effects on the production and diversity of
marine life and on the quality of our shorelines and marine waters.
•	Affect the community and ecological legacy we leave to our
children and grandchildren.
What Can I Do?
Your Tool Box
•	Get septic savvy: maintain your septic
system well. Contact Washington State
University Cooperative Extension,
Marine Advisory Services.
•	Use natural landscaping and low impact
development: Seethe information on
natural lawn care at King County | Yard
and Garden Topics and Washington
Department of Fish and Wildlife |
Landscaping for Wldlife. Check out the
Department of Fisheries and Oceans
Shorekeepers Program. Read the Puget
Sound Action Team Low Impact Devel-
opment Technical Guidance Manual for
Puget Sound.
•	Deal with pet waste: Always carry a
plastic bag to pick up after your pet. Pay
attention to the "no dog" signs at beaches.
•	Adopt environmentally preferable
purchasing programs.
•	Reduce and control polluted stormwater
runoff: Impervious surfaces and most
stormwater systems provide a quick
gateway for contaminants to get into local
streams, lakes and beaches.
What Are We Doing About It?
Marine water quality responses include:
reducing the level of nutrients in our waste
discharges, reducing nutrients and other
pollution in stormwater run off, using low impact
development approaches and natural landscap-
ing, implementing farm and manure manage-
ment plans, and using buffers and native
vegetation to filter and take-up nutrients that
would otherwise become pollution as they
reach water bodies.
Learn more http://www.epa.gov/regionlO/psgb/indicators/
Share what's important to you and yourcommunity
http://www.epa.gov/regionlO/psgb/contact/
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The Puget Sound Georgia Basin Ecosystem Indicators Report is a collaborative effort broughtto you by Federal,
State, Provincial and Local partners from the United States and Canada.

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