Water Quality Improvement Project
Weaver Creek Area:


Weaver Creek is a small stream located about 3 kilometers (km) northeast of the city of Battle Ground, Washington. It is in water resource inventory area (WRIA) 28, which is in the southwest corner of the state. The stream empties into Salmon Creek, which is a tributary of Vancouver Lake. Water flow in Weaver Creek is low during the late summer period.

Water quality issues

Weaver Creek did not meet water quality standards for dissolved oxygen. It has limited capacity to receive treatment plant effluent.

A 1978 study found that the Battle Ground sewage treatment plant (STP) discharged to Weaver Creek, about 4 km before the creek's headwaters. Below this discharge, the stream flows another 3.6 km into Salmon Creek. Because of the characteristics of Weaver Creek, Battle Ground’s waste discharge permit required that the effluent be treated to tertiary standards. Due to the increasing demands on the treatment facility, particularly with respect to hydraulic loading contributions, violations of the effluent standards were frequent. The 1978 study and other studies determined that the high concentration of ammonia-nitrogen in the effluent discharged by the Battle Ground STP caused the low levels of dissolved oxygen in the water.

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.

Status of the project

In 1993 the Department of Ecology developed a total maximum daily load (TMDL) to help bring Weaver Creek into compliance with the state water quality standards for biochemical oxygen demand (BOD) and ammonia-nitrogen (ammonia-n). Ecology specified wasteload allocations (WLAs) for the Battle Ground STP. The Environmental Protection Agency (EPA) approved the TMDL in March 1993.

The Infiltration/Inflow, Sewage, Treatment Plant and Receiving Stream Evaluation Report by Whiteley, Jacobsen, and Associates was completed to evaluate alternatives for the long-term sewer needs of the Battle Ground area. The report concluded that Battle Ground should discharge treatment plant effluent to the East Fork of the Lewis River. However, with stringent treatment requirements, public opposition, and environmental concerns, this alternative became undesirable. The final preferred alternative was to transport wastewater to the Clark County Salmon Creek Treatment Plant (SCTP).

A significant factor in Battle Ground's decision to proceed with this option was a Clark County proposal to sewer the Meadow Glade community with a pressure sewer extending nearly nine miles to the SCTP collection system. Clark County offered Battle Ground the opportunity to pay the cost of oversizing the Meadow Glade pressure sewer, which would greatly reduce Battle Ground’s buy-in cost. Battle Ground opted to abandon its STP and construct a pumping station and force main to deliver wastewater flows to the county treatment facility.

An Inter-local Agreement was signed on December 21, 1988, between Clark County and the Battle Ground for the construction and operation of the wastewater facilities that would convey Battle Ground's wastewater to Clark County. By April 1993, the new pump station and force main were on-line, and the Battle Ground's treatment facilities were abandoned or incorporated into the new wastewater transmission system. The moratorium on sewer connections was removed on April 15, 1993.

Weaver Creek continues to exceed (not meet) the water quality criteria for temperature, dissolved oxygen, and fecal coliform. For more information on what is being done to address these pollution problems visit the Salmon Creek area Water Quality Improvement website.

Technical information

Weaver Creek Biochemical Oxygen Demand and Ammonia-Nitrogen Total Maximum Daily Load (Ecology Publication)

Related information

Weaver Creek Low-Flow, Point Source Reconnaissance. Memo to Jon Neel. (Ecology Publication)

Weaver Creek: Battle Ground Sewage Treatment Plant Impact Study (Ecology Publication)

WRIA 28: Salmon-Washougal Watershed Information (Water web site)


Back to top of page

Last updated Marcy 2016
  Map for water resource inventory area (WRIA) 28, Washington State.


WRIA: 28 - Salmon-Washougal
County: Clark

Water-body Name:
Weaver Creek

Biochemical Oxygen Demand

# of TMDLs: 2

Status: TMDL Approved by EPA

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

Vancouver Field Office
WA Department of Ecology
2108 Grand Blvd
Vancouver, WA 98661-4622