Water Quality Improvement Project
Lake Whatcom Area:

Current Developments

November 2015

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 implementation requirements.

In October 2015, staff from Whatcom County and Ecology came to a mutually agreeable set of clarifications. EPA was satisfied that the proposed clarifications did not modify the TMDL and has resumed their review.

Ecology considers the dispute resolved and on November 12, 2015, requested Whatcom County to confirm this resolution.

The requirements of the TMDL become official after the EPA approval.

Next Steps

  • Whatcom County executive and the council will confer and reply to Ecology’s November 12, 2015 letter.
  • 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 the EPA approval. In 2018, Ecology will issue the new permits for discharge to Lake Whatcom, which will include the requirements set forth by the TMDL.


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 lake.

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).

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

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

Related information

Ecology closure letter (November 12, 2015)
Letter asking for confirmation that dispute is resolved.

Lake Whatcom Total Phosphorus and Bacteria TMDL Clarifications
Mutually agreeable clarifications on TMDL implementation.

Ecology Petition Response (January 14, 2015)
Response to Whatcom County petition

Whatcom County Petition (December 18, 2014)
Request for dispute resolution.

Lake Whatcom water quality still slipping, data shows (March 17, 2011)
The Bellingham Herald article

Ecology accepts plan for better protection of water quality in Lake Whatcom (March 11, 2011)
Ecology news release

State rejects well drilling ban, approves county plan for Lake Whatcom safeguards (March 11, 2011)
The Bellingham Herald article

Focus on Lake Whatcom TMDL: Draft study identifies limits for Lake Whatcom phosphorus and bacteria

City of Bellingham Petition to Amend WAC 173-501-060 and WAC 173-501-070

Ecology denial letter to Mayor of Bellingham

Whatcom County letter of commitment

Ecology’s April 29, 2011 response to Whatcom County’s list of proposed code sections and development standards to be addressed

Whatcom County May 18, 2011 response to Ecology comments

Whatcom County July 18, 2011 notification of revised schedule

Workshops on new developments scheduled

Focus on Lake Whatcom: State working with city, county to improve water quality protections for Lake Whatcom

Frequently Asked Questions on Ecology's Petition Response: How Ecology′s alternative to the Lake Whatcom petition will serve to protect the lake′s water quality

WRIA 1: Nooksack Watershed Information (Water web site)


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Last updated November 2015
  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: ---

Submitted to EPA for approval

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