North Bay is located at the north end of Case Inlet in the South Puget Sound. The bay is approximately 3.5 miles long and one mile wide. North Bay’s popularity is contributed to its’ beautiful views, numerous water recreation opportunities, and shellfish harvesting.

In August 2017, The Washington Department of Health downgraded approximately 130 acres in North Bay due to Fecal Coliform bacteria pollution. In accordance with RCW 90.72.045, Mason County Public Health has created a Closure Response Plan to identify and correct various nonpoint pollution sources.

In addition, Mason County has partnered with Pierce and Thurston Counties to form the South Sound Partnership (SSP) for water quality improvement. This partnership has been the recipient of a National Estuary Program grant, through the EPA

Non-Point Pollution Sources:

  • Malfunctioning septic or sewer components
  • Wildlife such as raccoons, possums and birds
  • Pet waste
  • Stormwater runoff
  • Agriculture and livestock


For further information and questions contact environmental health staff at 360-427-9670, extension 400.