Water Quality Improvement Project
On April 7, 2016, EPA approved a water quality improvement plan for Lake Whatcom.
The plan, called the
Lake Whatcom Watershed Total Phosphorus and Bacteria TMDL (total maximum daily load) addresses an elevated amount of phosphorous, which causes excessive growth of algae blooms and low dissolved oxygen levels.
The approved plan identifies the reductions in phosphorus and bacteria loading needed to restore the health of Lake Whatcom. It also establishes a link between increasing phosphorus levels and urban development.
The plan says that 87 percent of the developed area around the lake needs to store and filter water like a natural forest.
The requirements of the TMDL are now official. Implementation will be the responsibility of the city of Bellingham and Whatcom County.
- A TMDL work plan, including a budget and timeline, is due to Ecology by October 7, 2016.
- In 2018, Ecology will issue the new municipal stormwater permits that will incorporate the targets set forth by the TMDL work plans.
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.
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 Study Area map).
Ecology finalized and submitted the plan to EPA in November 2014.
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
Lake Whatcom Model Calibration
Lake Whatcom Model Calibration: Memorandum to the Washington State Department of Ecology
Lake Whatcom Water Quality Model
Lake Whatcom Model calibration with variable stoichiometry in sediments - REVISED: Memorandum to the Washington State Department of Ecology
Lake Whatcom Model Recalibration: Memorandum to the Washington State Department of Ecology
FINAL Model Report for Lake Whatcom Watershed TMDL Model Project
Amendment to Lake Whatcom TMDL Final Modeling Report - Full Buildout/Rollback Scenarios and Translator (Cadmus Group, Inc. & CDM)
Lake Whatcom TMDL Model - Partial Rollback Scenarios
Lake Whatcom Models Review
Guide to modeling files and data
(model data guide)
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
Lake Whatcom Total Maximum Daily Load Groundwater Study