Does anyone know how to check the safety of South Lake Union's beach?

I found this chart but it doesn't seem like they test South Lake Union. I found an old reddit post where people talk about it but no sourcing. I just want to be able to check if it's generally safe to swim it. Any help would be appreciated. http://ift.tt/1JNfUXF

Submitted July 24, 2016 at 10:22PM by it-is-sandwich-time http://ift.tt/2aqP5Oz