Knowlesway Extension Waterfront Public Access Point, is located at 220 Knowlesway Ext, Narragansett, RI 02882 on Google Maps. Coming down Point Judith Road (Route 108) you take a right at the Cumberland Farms across from St. Mary Star of the Sea Church. There is no public lot, but street parking seems to be permitted. There is a picnic table, and stairs leading down to the water.
I found reference to this as a public access point in the Coastal Public Access Inventory for the Narragansett Conservation Commission, on the Coastal Resources Management Council website, and in Google Maps.
Few pictures here: