I'm no expert, but I think it depends on the temperatures at the time of your stay, and the temperatures you're used to.
We're used to things being a bit cooler in Seattle, so when we went we felt too hot most of the time, and welcomed the chance to crawl into the pool, especially at mid-day. (A couple dips in the evening were cut short, though, when DS2 started to shiver and asked to leave.)
It looks like the average high temp is mid-70s. If that feels like swimming weather to you, go for it!
PS. Not sure, but I don't think the pool at the DLH was heated...