A bridge crosses the Yachats River near milepost 164 on US 101 in Yachats on the Oregon coast. South of the bridge, Yachats Ocean Road makes a loop along the shore of the cove before rejoining Highway 101 a few hundred yards farther south. Along the south shore of the cove, you'll find Yachats Ocean Road State Natural Site.
The mouth of the Yachats River is basically a cove at low tide and a bay at high, with the surface of most of the sand lying between the tides. At lower tides, the YORSNS is the best access to the largest beach close by downtown Yachats. The river usually clings to the bank on the north side of the cove, leaving little to no sand on the downtown side. If rocky shore is more your thing than sand, follow the beach to the south and find your bliss.
It's a short walk from downtown south on Highway 101, around the cove, and out Ocean Road to the State Natural Site.
More at 100 Steps, CoastalAtlas.net, OregonCoastTravel.net, OutdoorProject.org, StateParks.com, Travel Oregon, Wikipedia, Google Image Search.