$name - King County

Matthews Beach 0818SB

For algal toxin data please visit the State Toxic Algae web page and follow the “Find Lake” menu.

Please select a site and a year

The last year this beach was monitored is 2022. Please select a year from the drop down menu.

Table Legend

Cell Color	Fecal Coliform Value	Concern Level
	Individual day <= 200 CFU/100 ml	Low Concern - safe for swimming
	Individual day > 200 & <= 1000 CFU/100 ml	Moderate Concern – still safe for swimming
	Individual day > 1000 CFU/100 ml or geometric mean > 200 CFU/100 ml	High Concern – flagged for resample. For more information see Beach Closure Protocol – Fecal coliform bacteria

NOTE: Beach closure and reopening decisions are made by Public Health – Seattle & King County. Decisions are based on these results plus additional information about beach conditions, and may not always match the concern levels shown here.

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Seattle Parks and Recreation

Due to high bacteria counts, do not wade in Thornton Creek
Learn more about the pump station