This open-source project produces a service that gathers historical record-high/record-low and real-time lake water temperatures for Lake Washington and Lake Sammamish from King County Washington data sources.
The Seattle Lakes mobile app for Andriod and iOS uses this web service to fetch and display water temperature data.
Current Lake Washington and Lake Sammamish water temperatures, measured from a depth of 1 meter, are published in JSON format here.
Record all-time, and by-month high and low Lake Washington and Lake Sammamish water temperatures, measured from a depth of 1 meter, are published in JSON format here.
Read more about how this web service was implemented on the Ten Moments website.