Green Lake Duck Island Launch

Seattle, Washington

Green Lake boat launch on the northwest side near the tennis courts.

WATER QUALITY
  • Passed water quality tests at least 95% of the time
  • Historical Status
  • This status is based on the latest sample, taken on June 10th, 2019. Puget Soundkeeper Alliance updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on at
For water quality icon legend, click:   
MONITORING FREQUENCY

Green Lake Duck Island Launch is sampled weekly from May 1st to September 1st

SOURCE INFORMATION

The King County Department of Natural Resources and Parks monitors water quality at designated swimming beaches in the county from May to September. Water quality data is collected weekly, usually on Mondays. Results are generally posted to the King County Swimming Beach Bacteria Monitoring page by noon on Wednesday.

During the sampling period, Puget Soundkeeper Alliance regularly updates the Swim Guide to reflect the most current information. Local health officials use the following protocol to make closure determinations – A day’s average E. coli value is over 1000 CFU/100 mL – OR - The average of the E. coli values for the three most recent sampling days is over 200 CFU/100 mL. The three-day average is calculated using the geometric mean (geomean). The unit of measure is a CFU which stands for Colony Forming Units.

A beach is marked Green (open) when both of these protocols are met.
A beach is marked Red (closed) when these criteria are not met and the public health officials have closed the beach.

A beach may also be marked Red if there is a Harmful Algal Bloom (HAB) reported at the beach. A beach is marked Grey when current water quality data is not available. The King County Water and Land Resources Division (WLRD) collects and analyzes the samples. Public Health Seattle & King County is alerted when bacteria or state algal toxin thresholds are exceeded and determines the health and safety implications of the bacteria and algal toxin data collected, and they work with King County WLRD and the local park manager to post an advisory.

For more information go to King County Swimming Beach Bacteria Monitoring website: kingcounty.gov/swimbeach.

WATER QUALITY GRAPH

Green Lake Duck Island Launch

Seattle, Washington

WATER QUALITY
  • Passed water quality tests at least 95% of the time
  • Historical Status
  • This status is based on the latest sample, taken on June 10th, 2019. Puget Soundkeeper Alliance updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on at
For water quality icon legend, click:   

Green Lake boat launch on the northwest side near the tennis courts.

MONITORING FREQUENCY

Green Lake Duck Island Launch is sampled weekly from May 1st to September 1st

SOURCE INFORMATION

The King County Department of Natural Resources and Parks monitors water quality at designated swimming beaches in the county from May to September. Water quality data is collected weekly, usually on Mondays. Results are generally posted to the King County Swimming Beach Bacteria Monitoring page by noon on Wednesday.

During the sampling period, Puget Soundkeeper Alliance regularly updates the Swim Guide to reflect the most current information. Local health officials use the following protocol to make closure determinations – A day’s average E. coli value is over 1000 CFU/100 mL – OR - The average of the E. coli values for the three most recent sampling days is over 200 CFU/100 mL. The three-day average is calculated using the geometric mean (geomean). The unit of measure is a CFU which stands for Colony Forming Units.

A beach is marked Green (open) when both of these protocols are met.
A beach is marked Red (closed) when these criteria are not met and the public health officials have closed the beach.

A beach may also be marked Red if there is a Harmful Algal Bloom (HAB) reported at the beach. A beach is marked Grey when current water quality data is not available. The King County Water and Land Resources Division (WLRD) collects and analyzes the samples. Public Health Seattle & King County is alerted when bacteria or state algal toxin thresholds are exceeded and determines the health and safety implications of the bacteria and algal toxin data collected, and they work with King County WLRD and the local park manager to post an advisory.

For more information go to King County Swimming Beach Bacteria Monitoring website: kingcounty.gov/swimbeach.

WATER QUALITY GRAPH



Swim Guide
is supported by
* The RBC Foundation

Swim Guide shares the best information we have at the moment you ask for it. Always obey signs at the beach or advisories from official government agencies. Stay alert and check for other swimming hazards such as dangerous currents and tides. Please report your pollution concerns so Affiliates can help keep other beach-goers safe.

Swim Guide, "Swim Drink Fish icons," and associated trademarks are owned by SWIM DRINK FISH CANADA.| See Legal.

© SWIM DRINK FISH CANADA, 2011 - 2019