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Lake Whatcom multi-parameter 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. 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.

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 source 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

We worked with Bellingham and Whatcom County to develop a TMDL for fecal coliform and phosphorus to improve the levels of dissolved oxygen in Lake Whatcom. Once the TMDL report was finalized we submitted it to the Environmental Protection Agency (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.

Status of the project

Bellingham and Whatcom County are developing the milestones for the next 10 years that will demonstrate they are meeting the schedule. They are also getting a jump on the requirement to update models by hiring a peer review of the improved runoff model.

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

Next steps:

  • The city of Bellingham and Whatcom County will send us milestones that will define adequate progress by the end of October 2017.
  • We will incorporate the first five years of milestones into their stormwater permits when they are reissued in 2018.

There are also efforts to educate the public about the proper handling and disposal of pet waste to reduce exposure to stormwater.

Why this matters

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. This impacted water requires more treatment to make the drinking water safe. That process creates more trihalomethanes, a byproduct that some studies link to cancer.

Phosphorus is the main cause of Lake Whatcom’s low-oxygen problem. Phosphorus occurs naturally. It is found in soil and human and animal waste, and is added to some detergents. Sources of phosphorus include runoff from bare soil and developed areas. Development increases the amount of phosphorus entering the lake in stormwater.

Phosphorus feeds algae growth, and excess phosphorus creates larger algae blooms. 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.

Fecal coliform bacteria originates in human and animal waste. Runoff carries the bacteria from the ground and from failing septic systems to ditches and creeks, which deposit it 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.

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. The filtration of stormwater through soil or sand filters helps address phosphorus and fecal coliform.