Water Quality Improvement Project
Ecology submitted the final Lake Whatcom water quality improvement study to
the EPA in November 2014.
Over a decade in the making, the water quality improvement study, known as
the Lake Whatcom TMDL (total maximum daily load) concluded that in order to
restore the health and quality of the lake, approximately 87 percent of the
current development around the lake needs to be able to store and filter
stormwater like a forest, and bacteria levels in the most contaminated streams
need to be reduced up to 96 percent.
In December 2014, Whatcom County requested a dispute resolution to clarify
In October 2015, staff from Whatcom County and Ecology came to a
agreeable set of clarifications. The proposed
clarifications did not modify the TMDL.
In November 2015, Ecology and
Whatcom County confirmed that clarifications
were reached and the dispute was resolved.
- EPA will send an approval letter when they are satisfied the
TMDL meets the requirements of the Clean Water Act.
- The requirements of the TMDL become official after approval
from the EPA.
Lake Whatcom is a large natural lake in Whatcom County. The northwest end of
the lake lies within the city of Bellingham, and 22 small watersheds drain into
the lake. Lake Whatcom serves as the drinking water source for about 96,000
people in the Bellingham area. The lake is popular for recreation, and the area
around it has become a popular place to live.
Water quality issues
The lake has been threatened by declining water quality and in 1998
was put on the state’s
list of polluted water bodies. The primary concern is low levels of
dissolved oxygen as a result of increased levels of phosphorous and
fecal coliform bacteria. A lack of oxygen threatens the survival of fish
and aquatic plants. In addition, too much phosphorous can create an
overgrowth of algae which can increase drinking water treatments costs
and may require the use of more treatment chemicals.
Stormwater is the primary vehicle for phosphorous. Roofs, roads, driveways
and lawns speed the flow of stormwater to the lake without the benefit of
filtering out the phosphorous. In undeveloped areas, stormwater is allowed to
slowly seep into the ground where it is filtered naturally before it reaches the
The problems in Lake Whatcom triggered a water quality improvement project,
the Lake Whatcom TMDL. From the beginning, the goal was to determine how much
pollution the lake can process and still achieve acceptable levels of oxygen (See
Why this matters
Phosphorus is the main cause of Lake Whatcom’s low-oxygen problem. Phosphorus
occurs naturally, but development increases phosphorus entering the lake in
stormwater. Computer predictions show the lake would meet state standards for
oxygen if there was 86 percent less development than existed in 2003. Since then, zoning laws have allowed more development in the watershed.
Sources: Runoff from bare soil and developed areas. Phosphorus occurs naturally in
soil and human and animal waste, and is added to some detergents.
Connection to algae and oxygen: Phosphorus feeds algae growth. Bacteria that
consume dying algae deplete the oxygen that fish and other aquatic life need to
survive. When oxygen levels are low, phosphorus is released from lake sediment
and re-enters the water, perpetuating the cycle. The dissolved oxygen levels in
Lake Whatcom fail to meet state water quality standards now, and they have the
potential to get much worse, making the problem much harder to fix.
Treatment of drinking water: Excess phosphorus creates larger algae blooms,
which require more treatment to make the water safe for drinking. That process
creates more trihalomethanes, a byproduct that some studies link to cancer.
Effect of development: Roofs, driveways and lawns interrupt the absorption
and filtration provided by forests and soils, instead sending phosphorus-laden
stormwater rushing to the lake. Communities must modify existing and future
development to create the same effect as removing development.
Fecal coliform bacteria originate in human and animal waste. Runoff carries
the bacteria from the ground and from failing septic systems into the lake. Eleven
tributaries feeding Lake Whatcom fail to meet state standards for fecal coliform
bacteria. The bacteria create a health risk for people who work or play in and
around the water.
Unless otherwise specified, the following documents are Ecology publications:
Lake Whatcom Watershed Total Phosphorus and Bacteria Total Maximum Daily
Loads: Volume 2. Water Quality Improvement Report and Implementation Strategy
Lake Whatcom Watershed Total Phosphorus and Bacteria Total Maximum
Daily Loads: Volume 1. Water Quality Study Findings
Dissolved Oxygen in Lake Whatcom/Trend in the Depletion of Hypolimnetic
Oxygen in Basin I 83-97
Quality Assurance Project Plan: Lake Whatcom TMDL Study
Quality Assurance Project Plan: Characterization of Groundwater Discharge to
Lake Whatcom Total Maximum Daily Load Groundwater Study
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