Watershed and Lake Facts

Photo by K. Moran, 2014

Physical Characteristics

  • Lake Whatcom is about ten miles long and just over one mile wide at its widest point.

  • Lake Whatcom’s total shoreline is about 30 miles long.

  • Lake Whatcom’s surface area is about 5,000 acres with 92% outside of city limits.

  • Lake Whatcom is made up of three distinct basins that hold about 250 billion gallons of water.

  • Lake Whatcom’s watershed covers about 56 square miles (36,000 acres) with 97% outside of city limits.

  • Lake Whatcom is fed by 36 streams (many do not flow year-round). Major streams include Silver Beach, Carpenter, Olsen, Smith, Anderson, Brannian and Austin Creeks.

  • Lake Whatcom also periodically receives water diverted from the Middle Fork of the Nooksack River by the City of Bellingham to meet water supply needs.

  • The City of Bellingham controls lake level with a small dam at the outlet draining to Whatcom Creek. When the lake level reaches 314.94 feet above mean sea level the city is obligated to release water through this dam.

  • Lake Whatcom’s natural outflow is to Whatcom Creek and Bellingham Bay.

  • Lake Whatcom’s depth ranges from 15 feet deep to 334 feet deep.

Population and Drinking Water Supply

  • Lake Whatcom is the drinking water source for over 100,000 Whatcom County residents, which is about half the county’s population.

  • Lake Whatcom provides drinking water for the City of Bellingham, Lake Whatcom Water and Sewer District, several smaller water districts and associations, and homes that draw water directly from the lake.

  • The City of Bellingham withdraws water from the lake’s middle basin through a 1,200-foot wooden pipeline. The water is piped to the water treatment plant in Whatcom Falls Park.

  • About 18,000 people live in the Lake Whatcom watershed (2018 estimate).

  • Approximately 25% of the watershed population lives within the City of Bellingham and approximately 75% live outside city limits in unincorporated Whatcom County.