Water Quality Improvement
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
Weaver Creek Biochemical Oxygen Demand and Ammonia-Nitrogen Total
Maximum Daily Load (Ecology Publication)
Weaver Creek Low-Flow, Point Source Reconnaissance. Memo to Jon Neel.
Weaver Creek: Battle Ground Sewage Treatment Plant Impact Study (Ecology
WRIA 28: Salmon-Washougal Watershed Information (Water web site)
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Last updated Marcy