Big River Estuary or other swim spots near Mendocino?

Have any of you swum in Mendocino's Big River Estuary (the river side, not the ocean side)? What's it like? And/or are there other good swim spots near the town of Mendocino, California? I'm accustomed to swimming in SF's Aquatic Park, so cooler temps don't worry me, but strong currents do.