Water Quality Improvement Project
Puyallup River Basin Area:


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 River.

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.

Technical information

Addendum to Puyallup River TMDL, 1994 (Ecology publication)

Puyallup River Total Maximum Daily Load, Submittal (Ecology publication)

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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Last updated November 2015
  Water resource inventory area (WRIA) 10 map, Washington State.


WRIA: #10 (Puyallup-White)
County: Pierce

Water-body Name:
Puyallup River

Biological Oxygen Demand (BOD)

# of TMDLs:
BOD - 23
Ammonia - 23

Approved by EPA

Contact Info:
Donovan Gray
Phone: 360-407-6407
Email: Donovan.Gray@ecy.wa.gov

Southwest Region
Department of Ecology
P.O. Box 47775
Olympia, WA 98504-7775