Swimming (open water or pool) near Seattle Airport

I will be in Seattle for a conference in mid September, and I am staying in a hotel right next to airport. Are there any pools or lakes close to airport? It looks like Angle Lake is a mile from my hotel. Is that lake suitable for swimming? What would potential water temps be in Sept. for that lake? I may not have a car so I am looking for something fairly close.

This wont really help if you dont have a car but King County Aquatic Center is about 15-20 minutes south on I-5. It is a really nice pool but I am not sure about anything closer.

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