Water Quality Improvement Projects
Snoqualmie River Basin
The Snoqualmie River watershed is an important state and community
resource. Its highest points reach up to Snoqualmie Pass. From those
upper reaches, the Snoqualmie flows through federal, state, and private
forest lands down to Snoqualmie Falls. Below the Falls the watershed
becomes an important spawning and rearing area for several salmonid
species. Chinook are known to spawn heavily in the mainstem, just below
the confluences of the Raging and Tolt rivers.
The watershed is also heavily used for recreation and agricultural uses.
Fishing, recreational boating, swimming, and tubing are popular
activities. Ranchers and crop farmers depend on clean water from the
watershed to raise livestock and grow safe and healthy food.
Water quality issues
Although the water quality is good in the Snoqualmie watershed in many
respects, there are two areas that need improvement: bacteria and water
temperature. In some tributary streams, bacteria levels are still too
high. Bacteria levels in the main river have improved greatly over the
last 10 years and are in pretty good shape. Water temperatures
throughout the watershed are much too high during the summer. The
removal of trees and other modifications to the land have made the
watershed a much less hospitable place for cold-water fish to live.
Status of the projects
We prepared a report on the high water temperatures found throughout the
watershed and what needs to be done to resolve the problem. The
draft water quality improvement report and
implementation plan was available for review and comment through June
17, 2011. After Ecology responded to the comments received and
document, we submitted the TMDL to the Environmental Protection
Agency (EPA) for approval on June 30, 2011. EPA approved the TMDL on August 4,
Ammonia-N, BOD (5 day), and Fecal Coliform
Ecology submitted a TMDL for ammonia-N, BOD, and fecal coliform to
EPA. EPA approved it in July 1996. In March 2008, we published our
updated study on fecal coliform bacteria,
dissolved oxygen, ammonia-nitrogen, and pH levels in the watershed in order to determine the effectiveness of Total Maximum Daily Load
(TMDL) clean-up efforts in the lower Snoqualmie River basin.
Why this matters
Ammonia (NH4+) is one measure of nitrogen, a nutrient that can
increase the growth of plants and algae in water. When
higher-than-normal levels of nutrients are present, plants and algae can
get out of control and lead to changes in the water’s pH, dissolved
oxygen and clarity. In addition, increased algae and plants can be ugly,
create odor problems when they die, decompose and interfere with
recreational activities like boating and swimming. In fresh waters
Ammonia-N is toxic to aquatic organisms and contributes to biological
oxygen demand (BOD).
Biological Oxygen Demand (BOD) is the amount of oxygen required by
aerobic microorganisms (organisms that need oxygen to survive) to break down
organic matter in water. It can be used to measure the amount of water pollution
in a water body. High BOD values can lower dissolved oxygen levels, which are
important to the health of fish and other aquatic organisms.
Fecal coliform is a type of “bacteria” common in human and animal
waste. It indicates that sewage or manure is entering a water body. As the level
of fecal coliform increases the risk of people getting sick from playing or
working in the water increases. Bacteria can get into our waters from untreated
or partially treated discharges from wastewater treatment plants, from
improperly functioning septic systems, and from livestock, pets and wildlife.
People can help keep bacteria out of the water. Properly collect, bag, and
trash dog poop. Check your on-site sewage system to make sure it is maintained
and working properly. Ensure livestock and manure are kept away from the water.
Water temperature influences what types of organisms can live in a water
body. Cooler water can hold more dissolved oxygen that fish and other aquatic
life need to breathe. Warmer water holds less dissolved oxygen. Many fish need
cold, clean water to survive.
One way to cool water temperature is to shade the water body by adding or
retaining streamside vegetation.
Snoqualmie River Basin Temperature Total Maximum Daily Load: WQIR-IP
Ammonia-N, BOD (5 day), and Fecal Coliform
Snoqualmie River Basin Fecal Coliform
Bacteria, Dissolved Oxygen, Ammonia-Nitrogen, and pH Total Maximum
Daily Load: Water Quality Effectiveness Monitoring Report
Snoqualmie River Total Maximum Daily Load
Focus on Snoqualmie Watershed: Streams Too Warm
Snoqualmie Watershed Water Quality Synthesis Report: January 2009 (Salmon
Conservation and Restoration)
WRIA 7: Lower Snohomish
Watershed Information (Water web site)
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Last updated June
WRIA(s): #7 (Snohomish)
Fecal coliform bacteria
# of TMDLs:
Ammonia-N, BOD, Fecal Coliform -16
Temperature - 17
Ammonia-N, BOD, Fecal Coliform - approved by EPA
Temperature - approved by EPA; has implementation plan
Department of Ecology
3190 - 160th Ave. SE
Bellevue, WA 98008-5452