This is a fairly new beach (2012?), part of a major rehabilitation of this park on the north side of the town of Chelan. It appears to be a nice example of what happens when a team of landscape architects, waterfront engineers, and shoreline designers come together with a community willing to try something new.
The beach is constructed of pea gravel organized behind a couple of rock groins that reorient the beach to better take advantage of the westerly waves. It looked like the beach was still making small adjustments - which is sort of typical for these kinds of projects. And must be an interesting challenge on lakes with substantial swings in water level over the year.
There is a broad sandy backshore, somewhere beneath which is the original bulkhead (or at least that's how I understand it).