Water Quality Improvement Project
Puyallup River Basin
The Puyallup River drainage basin covers approximately 970 square miles in
the Puget Lowland of Washington State. The major streams of the
basin are the Puyallup River and its two largest tributaries, the White and
Carbon rivers. The first 8.3 miles of the White River are also called the Stuck
Prior to 1906, the White River joined the Green River north of the
current Puyallup basin, except for occasional overflows to Stuck Creek and the
Puyallup River. In 1906, a flood modified the channel to block flow to the Green
River. The diversion dam at Auburn made this change permanent. It sends all White River flows through the channel previously
named Stuck Creek.
The lower reach of the Puyallup River is a relatively flat floodplain ranging
in elevation from sea level at Commencement Bay to approximately 50 feet at the
confluence of the White and Puyallup rivers. The lower Puyallup River is a
salt-wedge estuary, with deeper marine water overlain by a layer of fresh water.
The salt wedge generally extends less than 2.5 miles upstream from the river
mouth. Industrial activity is predominant below
Puyallup RM 2.0. Historically, much of the lower Puyallup valley above the tide
flats was used or agriculture. Small farms producing vegetables, flower bulbs,
and berries are declining in numbers due to encroachment of residential and
commercial development. Most of the upland developments are light to medium
density residential areas. Gravel is mined commercially at several locations
along the northeast and southwest valley walls.
Water quality issues
Dissolved oxygen standards in the lower Puyallup River would not be met if
significant additional biochemical oxygen demand (BOD) sources were introduced,
unless currently permitted BOD loads (nitrogenous BOD from ammonia and/or
carbonaceous BOD) are reduced. A total maximum daily load (TMDL) was developed
that established waste load allocations (WLAs) for point sources for BOD,
ammonia, and chlorine in the Puyallup River basin. Dischargers permitted through
the National Pollutant Discharge Elimination System (NPDES) include ten
municipalities, four industrial discharges, and four fish hatcheries. Background
and nonpoint source loads were also assessed. In addition to considering
existing discharges and nonpoint loads, the potential impact of future
dischargers was examined.
Why this matters
Ammonia (NH4+) is one measure of nitrogen, a nutrient that can
increase the growth of plants and algae in water. The presence of large
concentrations of ammonia in a stream or lake can create a large oxygen
demand. This demand is caused by the conversion of ammonia to nitrate,
called "nitrification". High concentrations of nitrate in wastewater
treatment plant effluent can cause algae to grow in large quantities.
Dead and decaying algae can cause oxygen depletion problems, which in
turn can kill fish and other aquatic organisms in streams.
Higher-than-normal levels of nutrients in the water can also lead to
changes in the water’s pH 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.
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.
Status of the project
A preventative water quality improvement project (TMDL) was completed and
approve by the EPA in
November 1994. Later, new
information became available that raised questions regarding the ability of
the river to assimilate capacity additional 5-day Biochemical Oxygen Demand
(BOD5) and ammonia loads.
A moratorium on access to the
reserve capacity for BODs and ammonia was set in December 2000.
The moratorium is based on the results of dissolved oxygen monitoring in
the summer of 2000, which showed that dissolved oxygen levels violated
water quality standards on several days.
Ecology is currently working with partners in the Puyallup River watershed on
a focused TMDL implementation effort. This work includes increased education and
outreach, a greater field presence to identify and eliminate nonpoint sources,
and work with NPDES permit managers and permitees to ensure TMDL point source
requirements are met. These efforts should help to reduce or eliminate sources
of excess nutrients.
Addendum to Puyallup River TMDL, 1994 (Ecology publication)
Puyallup River Total Maximum Daily Load, Submittal (Ecology
Puyallup River Total Maximum Daily Load, 1993 study (Ecology publication)
Quality Assurance Project
Plan: Puyallup and White Rivers Temperature and Dissolved Oxygen
Monitoring (Ecology publication)
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