Water Quality Improvement Project
Wildcat Creek Area:


Wildcat Creek is a small stream within the Chehalis River Basin. The stream is made up of three forks: the East, Middle and West forks. The East Fork originates several miles northeast of McCleary, Washington, entering Cloquallum Creek nine miles to the southwest. Wildcat Creek is particularly significant to salmon fisheries, with chum and coho utilizing the stream for spawning and rearing.

Water quality issues

In response to two significant fish kills in Wildcat Creek that occurred in 1970, several water quality studies of Wildcat Creek near McCleary found that improvements at the McCleary sewage treatment plant (STP) were needed to improve water quality in Wildcat Creek. Improvements to the STP were made in the 1980s, and a 1987 study to evaluate the effects of the STP improvements established total maximum daily load (TMDL) allocations for the STP, which were incorporated into their permit limits. This TMDL set load and wasteload allocations for ammonia-N and biological oxygen demand (BOD) in order to improve dissolved oxygen levels in the creek. The 1987 study concluded that the STP upgrade considerably improved water quality in Wildcat Creek, despite a 50% decline in the creek stream flows measured during the study, compared to the 1977 study period.

Ammonia (NH4+) is one measure of nitrogen, a nutrient that can increase the growth of plants and algae in water. 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 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 and 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.

Allocations for fecal coliform bacteria were also established by this TMDL to improve water quality in Wildcat Creek and protect people that recreate in and around the creek. 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.

TMDL implementation: getting to clean water

The McCleary STP (National Pollutant Discharge Elimination System [NPDES] Permit #WA0024040) was upgraded to the advanced secondary level in the winter of 1980-81. Subsequent monitoring found that the previous pollutions problems, except for temperature, were improved.

Technical information

TMDL reports are submitted to the U.S. EPA for approval. These documents are also called WQ Improvement Reports (WQIRs). Sometimes the study on which these reports are based is published separately as a TMDL study, or technical report, that describes the results and analysis of the study. The precursor to a study is a Quality Assurance Project Plan (QAPP). The QAPP describes the study design, data collection and data quality objectives. Important follow-up studies to a TMDL are also included in the following table. Unless otherwise specified the following documents are Ecology publications.

Document Type Pollutant Title Publication #
TMDL Reports Ammonia-Nitrogen
Biological Oxygen Demand (BOD)
Fecal Coliform
Wildcat Creek Ammonia-N, BOD, Total Residual Chlorine, and Fecal Coliform TMDL 93-10-208
TMDL Studies   Effects of McCleary Wastewater Treatment Plant Effluent on Water Quality and Macroinvertebrate Community Structure in Wildcat Creek, Washington 87-e24
Water Quality Studies of Wildcat Creek near McCleary, Washington 77-e22



Related information

WRIA 22 Watershed Information (Water web site)


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Last updated October 2016


WRIA: #22 (Lower Chehalis)
County: Grays Harbor

Water-body Name:
Wildcat Creek

Fecal coliform

# of TMDLs: 4

TMDL approved by EPA

Contact Info:
Brett Raunig
Phone: 360-690-4660
Email: Brett.Raunig@ecy.wa.gov

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