Hidden Lake

Hidden Lake is a dammed section of Boeing Creek upstream of Innis Arden Way. This is a constructed open water feature designed to improve aquatic habitat; it contains a sediment forebay to trap sediment as it moves into the lake. In order to keep the lake as an open-water feature, the City maintains it by removing sediment on an annual or biannual basis.

It is part of Boeing Creek Park, a wooded park with trails and picnic areas.

WATER QUALITY

Passed water quality tests at least 95% of the time
Historical Status
This status is based on the latest sample, taken on August 28th, 2018. 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:

Report Pollution

MONITORING FREQUENCY

SOURCE INFORMATION

During the sampling period, Puget Soundkeeper Alliance regularly updates the Swim Guide to reflect the most current information.

Local health officials follow the Ten State Standard –a geometric mean of 200 fecal coliforms with no single sample exceeding 1000 – to determine whether a swimming beach is polluted. The unit of measure is a CFU which stands for Colony Forming Units.

A beach is marked Green (open) when a single sample is below 1000 CFU/100ml and the geometric mean of the five most recent samples is below 200 CFU/100ml.

A beach is marked Red (closed) when either a single sample exceeds 1000 CFU/100ml or a geometric mean of the five most recent samples exceed 200 CFU/100ml

A beach is marked Grey when current water quality data is not available.

If a sample is found to exceed the Ten State Standard three new samples are collected. If the average of these samples confirms the results from the routine sample, Public Health Seattle & King County is alerted and determines the health and safety implications of the bacteria and algal toxin data collected and works with King County and the local park manager to post an advisory.

For more information go to King County Swimming Beach Bacteria Monitoring website: http://green2.kingcounty.gov/swimbeach/

WATER QUALITY GRAPH

Hidden Lake

Shoreline, Washington

Managed by Puget Soundkeeper Alliance

WATER QUALITY

Passed water quality tests at least 95% of the time
Historical Status
This status is based on the latest sample, taken on August 28th, 2018. 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

SOURCE INFORMATION

WATER QUALITY GRAPH

Beach	Location	Water Quality
Richmond Beach Saltwater Park Shoreline, Washington	Shoreline, Washington	Historical Status
Echo Lake Shoreline, Washington	Shoreline, Washington	Historical Status
Carkeek Park Seattle, Washington	Seattle, Washington	Historical Status
Edmonds Marina Beach Park Edmonds, Washington	Edmonds, Washington	Special Status

Other Beaches Near This One

Beach	Location	Water Quality
Richmond Beach Saltwater Park Shoreline, Washington	Shoreline, Washington	Historical Status
Echo Lake Shoreline, Washington	Shoreline, Washington	Historical Status
Carkeek Park Seattle, Washington	Seattle, Washington	Historical Status
Edmonds Marina Beach Park Edmonds, Washington	Edmonds, Washington	Special Status

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.

	Green means the beach’s most recent test results met relevant water quality standards.

	Red means the beach’s most recent test results failed to meet water quality standards.

	Grey means water quality information for the beach is too old (more than 7 days old) to be considered current, or that info is unavailable, or unreliable.

	Green means the beach passed water quality tests 95% of the time or more.

	Yellow means the beach passed water quality tests 60-95% of the time.

	Red means the beach failed water quality tests 40% of the time or more.

	Green means the beach has historically excellent or pristine water quality, but there is no current data.

	Red means the water at the site has water quality issues or there is an emergency.

	Grey means there is no current water quality information, the beach is under construction, there has been an event that has rendered water quality information unreliable or unavailable.