Marsh Creek State Park is not open to the public at this time. There is a small portion of the property (Round Valley Staging Area) that is open year-round and operated by an Operating Agreement with East Bay Regional Park District that serves as a parking & equestrian staging area for the public that serves East Bay Regional Park District owned property (Round Valley Regional Preserve). Link to EBRPD website: https://www.ebparks.org/parks/round-valley
Delta habitat and wildlife around the historic John Marsh Home, east of Brentwood. The site is not yet open to the public while planning and restoration continue.