Water Quality Improvement Project
South Prairie Creek Area:


South Prairie Creek starts in the Mt. Baker-Snoqualmie National Forest, near the northwest corner of Mt. Rainier National park, and flows to its connection with the Carbon River in the south-central Puget Sound region of Washington State. The South Prairie Creek watershed has three tributaries: Wilkeson Creek (the largest), Spiketon Creek (also known as Spiketon Ditch), and Inglin Creek which originates south of the town of South Prairie.

The climate in the area is typical of the Puget Lowlands and Cascades eco-region: wet, mild winters and dry, cool summers. Most of the average annual precipitation occurs between November and April. Winter precipitation is mainly rain in the lowlands and a mixture of rain and snow at higher elevations. The upper watershed is characterized by steeper gradients. The low-permeability valley bottom includes the developed areas of South Prairie, Wilkeson, Buckley, and Burnett. Current land use includes forestry operations in the higher elevations; small commercial and non-commercial farms in the lower watershed; and residential development. (See Study Area map)

Water quality issues

Temperature monitoring in 2000 and 2001 showed that some parts of South Prairie Creek and is tributaries exceed the state water quality standard for temperature. A study performed in 2003 showed that South Prairie Creek exceeded water quality standards for fecal coliform bacteria. Two permitted wastewater facilities discharge domestic wastewater to the South Prairie Creek watershed, on the South Prairie mainstem and the other on Wilkeson Creek. Both contribute both fecal coliform bacteria and heat loads to the receiving waters. Nonpoint sources of fecal coliform bacteria come from septic systems, commercial and non-commercial livestock operations, domestic animals, and wildlife. Bacteria loads are released directly to water bodies or indirectly through subsurface loads or surface runoff.

Why this matters

Fecal coliform is a type of “bacteria” common in human and animal waste. It can make people sick and cause the closure of shellfish harvesting beds. 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.

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. Threatened and endangered salmon need cold, clean water to survive.

Stream temperature is influenced by decreasing effective shade; reducing surface water discharge; reducing groundwater exchange; or increasing stream surface area through channel widening. Removing local riparian vegetation reduces the amount of shortwave radiation absorbed by leaves in the canopy, which increases the amount that reaches the stream. These disturbances result in elevated temperatures that are carried downstream. As the amount of water in the stream decreases, the volume of water capable of absorbing the heat decreases and temperature increases.

One way to cool water temperature is to shade the water body by adding or retaining streamside vegetation.

What was done

Ecology performed a total maximum daily load (TMDL) study on South Prairie Creek. The study recommended various strategies to control fecal coliform and improve the water temperature, along with monitoring to check the progress of the strategies to help the creek meet state water quality standards. A water cleanup plan, or TMDL, which includes the study and an implementation strategy, was submitted to EPA. After EPA approved the TMDL, Ecology worked with local governments, tribes, and local interest groups to develop a detailed implementation plan, which was also sent to EPA. The detailed implementation plan spelled out what would be done to act on the recommendations in the study. Implementation activities began in 2006.

Status of the project

Ecology conducted follow-up monitoring on two tributaries of concern. Monitoring found unusually high levels of fecal coliform bacteria at a drain tile leading into a tributary to Inglin creek. A Pierce County Health Department investigation uncovered a septic system failure in the area. It was thought to be corrected as of January 2010.

Ecology is currently working with partners in the South Prairie Creek 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 the fecal coliform and temperature problem.

Technical information

Unless otherwise specified, the following documents are Ecology publications.

South Prairie Creek Bacteria and Temperature Total Maximum Daily Load Study

South Prairie Creek Bacteria and Temperature Total Maximum Daily Load (Water Cleanup Plan): Submittal Report

South Prairie Creek Bacteria and Temperature Total Maximum Daily Load (Water Cleanup Plan): Detailed Implementation Plan

Monitoring Plan:

Related information

Unless otherwise specified, the following documents are Ecology publications.

South Prairie Creek Tributaries Fecal Coliform Bacteria Data Summary: Inglin Creek and Spiketon Ditch

Memo: South Prairie Creek Watershed; Tile Drain T4DT on Tributary 4 to Inglin Creek Fecal Coliform concentrations March through May 2010 (Water Quality Program)

Focus on South Prairie Creek

WRIA 10: Puyallup-White Watershed Information (Water web site)


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Last updated November 2015

  Map of Puyallup-White water resource inventory area 10.


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

Water-body Name:
South Prairie Creek

Fecal Coliform

# of TMDLs: 6

TMDL approved by EPA
Has implementation plan

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