Refugio is one of several creeks draining the low hills of Contra Costa into San Pablo Bay. It flows for 4.4 miles in a valley of low hills trending northwest.
The watershed of Refugio Creek covers an area nine square miles. The creek enters San Pablo Bay a few miles west of the Carquinez Strait. https://en.wikipedia.org/wiki/Refugio_Creek
A mile further west on the north-facing bayfront is the outlet of Pinole Creek, draining the next watershed west of Refugio.
Hills forming the Refugio Valley are lower elevations of the Briones range, east of the Berkeley range. https://en.wikipedia.org/wiki/Briones_Hills#Geography