Water Quality Improvement Project
The Sumas River is a Class A waterbody located in Whatcom County. Water
in the Sumas River watershed is used mainly for agriculture, specifically dairy
farming. There are a number of dairy pastures along the banks of the Sumas
River. Johnson Creek, a major tributary to the Sumas River, meanders
through the city of Sumas before joining the Sumas River one mile above the
Sumas wastewater treatment plant (WWTP) outfall. It drains much
of the agricultural lands.
Water Quality Issues
At one time the Sumas River received water discharged from the town of Sumas WWTP. Studies found the following issues:
- There were specific concerns with BOD, ammonia-nitrogen, chlorine, and
- Dissolved oxygen (DO) violations from WWTP discharges sometimes occurred under
summer design conditions.
- Total residual Chlorine exceeded proposed daily permit limits under
both annual and seasonal discharge conditions.
- Nonpoint sources upstream of the WWTP may have contributed to fecal coliform
and nutrient loads to the Sumas River, mainly from agricultural discharges
to the Johnson Creek drainage.
Why this matters
Ammonia-N is a form of nitrogen, a nutrient. It is comes
from fertilizer applied to land, and can be carried into rivers, lakes and
streams through stormwater runoff, for example. Too many nutrients in the
water encourages the growth of algae, especially in lakes. As the algae
die and decompose in the water, the dissolved oxygen is used up, leaving less
available to fish and other aquatic life.
Biological oxygen demand (BOD) is a measure of the amount of
oxygen used by microorganisms to decompose organic matter in water. The amount
of nutrients in the water, e.g. nitrogen, can lead to high BOD levels as algae
grow, die, and are decomposed by bacteria which uses the oxygen in the water.
Chlorine is widely used to disinfect municipal wastewater.
Chlorine can irritate the skin and mucous membranes of fish, even at low levels.
If it combines with ammonia in the water, the resultant product can pass through
fish gills and enter the bloodstream, preventing oxygen from entering the blood
and causing suffocation.
What was done
On April 29, 1996 EPA approved the water quality-based National Primary Discharge Elimination
Systems Permit (NPDES) for the city of Sumas as a TMDL for the Sumas River
Biochemical Oxygen Deman, ammonia-nitrogen, and chlorine parameters. The
TMDL established seasonal loading capacities for BOD, total residual chlorine,
and ammonia-nitrogen. The city of Sumas WWTP was given a wasteload
allocation for all three parameters. The TMDL also included a load
allocation for the nonpoint sources, and an allowable mixing zone for
ammonia-nitrogen and chlorine.
The wasteload allocations were implemented through effluent limitation
conditions in the city of Sumas NPDES permit. The load allocations
represented the watershed conditions at that time. They were to be
maintained through Ecology's voluntary compliance program for nonpoint source
pollution control. Pollution sources not under NPDES authority could be
controlled through administrative order if voluntary compliance failed.
Status of the project
The city of Sumas no longer discharges treated sewage to the Sumas River.
They send their sewage to Canada for treatment by the Greater Vancouver Regional
District. Washington State's 2008 Water Quality Assessment lists the Sumas
River as category 1 - available data shows that the waterbody segment meets the
state's water quality standard for Ammonia-N.
There are no listings for BOD or chlorine in the 2008 assessment.
If the city resumes discharging to the river again, a new TMDL would be
necessary to establish appropriate wasteload allocations (WLAs), because the
oxygen criteria has been revised since the establishment of the TMDL, and
conditions are expected to be different than they were in 1992.
Sumas River Receiving Water Study (Ecology publication)
Approval of the Water Quality-Based National Primary Discharge Elimination
Systems Permit (NPDES) for the city of Sumas as a Total Maximum Daily Load
(TMDL) for Sumas River-Biochemical Oxygen Demand, Ammonia-Nitrogen, Chlorine
Washington State's Water Quality Assessment - Simple Query Tool
WRIA 1: Nooksack
Watershed Information (Water web site)
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WRIA: #1 (Nooksack)
Biochemical Oxygen Demand (BOD)
# of TMDLs: 3
TMDL project is complete for the above-listed parameters
Bellingham Field Office
Department of Ecology
1440 - 10th St., Suite 102
Bellingham, WA 98225-7028