Water Quality Improvement Project
Lake Whatcom

Current Developments

Photo of Lake Whatcom

Ecology received the TMDL work plan from the city of Bellingham and Whatcom County.

In their work plan they jointly set a target of full implementation of the Lake Whatcom TMDL in 50 years, at a cost of $100 million (2016 dollars). They commit to preparing the detailed implementation plan with 10 years' worth of milestones by October of 2017.

Next steps:

  • Milestones that will define adequate progress will be submitted to Ecology by the end of October 2017.
  • Ecology will incorporate the first 5 years of milestones into permit when they are reissued in 2018.


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. The lake has been threatened by declining water quality, and in 1998 was put on the state’s list of polluted water bodies.

We are working with Bellingham and Whatcom County to implement plans developed through a total maximum daily load (TMDL) process to bring Lake Whatcom water to meet state water quality standards for dissolved oxygen, fecal coliform bacteria (FC), and phosphorus.

Water quality issues

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. [See Study Area map]

The primary water quality concern is low levels of dissolved oxygen (DO) as a result of increased levels of phosphorous and fecal coliform bacteria. A lack of oxygen threatens the survival of fish and aquatic plants.

Stormwater is the chief vehicle for phosphorous and bacteria. Roofs, roads, driveways, and lawns speed the flow of stormwater to the lake without the benefit of filtering out the phosphorous and bacteria. In undeveloped areas, stormwater can slowly seep into the ground where it is filtered naturally before it reaches the lake. Computer predictions show the lake would meet state standards for dissolved oxygen if there was 86 percent less development than existed in 2003. Since then, zoning laws have allowed more development in the watershed.

These concerns triggered a water quality improvement project, the Lake Whatcom TMDL. The goal is to determine how much pollution the lake can process and still achieve acceptable levels of oxygen.

What has been done

Ecology finalized and submitted the plan to EPA in November 2014. EPA approved the TMDL in April 2016. Bellingham and Whatcom County sent a copy of a budget and timeline to implement the TMDL in 50 years, and a written enforcement process. Citizens can now confirm how codes are being enforced.

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.

Technical information

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 (website)

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

Whatcom County enforcement process (April 6, 2017)

City of Bellingham enforcement procedures (March 31, 2017)

City and County letter identifying Timeline and Budget for TMDL implementation


Related information




Last updated April 2017
  Water resource inventory area (WRIA) 1 map, Washington State.


WRIA(s): #1 (Nooksack)
County: Whatcom

Water-body Name:
Lake Whatcom

Fecal coliform bacteria

# of TMDLs: 12

EPA approved

Contact Info:
Steve Hood
Phone: 360-715-5211
Email: Steve.Hood@ecy.wa.gov

Bellingham Field Office
Department of Ecology
1440 - 10th St., Suite 102
Bellingham, WA 98225-7028