Trailer Park Wave marks the put-in for a Class III+ stretch of the Spokane River that runs down to the Idaho state line, named for the trailhead access point rather than any actual trailer park. It's a natural wave fed by releases out of the Post Falls Dam upstream, so what you get depends entirely on how much water is being let through that day. The river-right line is the one locals look for — it's where the wave actually stacks up enough to surf instead of just washing through. Flows here swing enormously, from a lazy float to serious high water, so check the Post Falls gauge before you commit.