There's a launch party for a new skate exhibit tonight in Silver Lake. / Photo by C-Monster via LAist's flickr pool. KAYAKING + LA River: Supporters are welcome to watch a group of fearless kayakers navigate the LA River – from the Valley to Long Beach. At 3 pm today, there’s a kick-off ceremony/"launch" at the LA River Headwaters on the overpass @ Owensmouth in Canoga Park. The kayakers will demonstrate to developers and......