The optimistically but accurately named "First Annual CAST Classic" races, put on by the Coeur d'Alene Area Swim Team, were August 14. They had 2.5K, 5K, and 10K distances for kids and adults (5K and 10K for 14 and over only). The event was well organized, upbeat, and safe. They set up a 2.5K loop and had people do one, two, or four laps, with a feeding station available for 10K swimmers. The lake was absolutely perfect--about 70F, smooth, and clear. Lots of the 10K swimmers (including me) had never swum a 10K before and it was an ideal introduction to the distance.
Coeur d'Alene itself is a charming place for a weekend, and the weather in August is fantastic. If you live within easy travel distance and you (and your teenager) want to swim a 5K or 10K next summer, consider coming to this event.
I drove up in the hills around Lake Coeur d'Alene last summer on my way to Glacier NP and thought how lovely it looked. I'm glad there is a meet there. I think if you were able to announce it in advance next year you might get a large turnout.
Is there camping not too far from the highway? I thought I saw a couple of signs, but not knowing how far or what the facilities were like, I didn't pursue it. And are there any public beaches?
It would make a nice break to or from Spokane airport.
Edit: You *were* speaking of Lake Coeur d'Alene in WA or ID, yes? Or is there one in California? About which I know nothing.