From Marin Municipal Water District:

 From early August through October, MMWD will replace a failed corrugated metal pipe culvert underneath the Cross Marin Trail at Jewell Creek. The culvert is in disrepair and has a decayed bottom affecting fish passage at this location. MMWD's Nicasio water transmission line, located above the failing culvert, is also at risk and could be damaged if the culvert fails. 

In place of the existing culvert, MMWD will install an open-bottom arch culvert, improving fish passage in Jewell Creek. This project will also restore the Cross Marin Trail and stabilize the Nicasio transmission line in the project vicinity.

The Cross Marin Trail will be closed south of Sir Francis Drake Blvd through National Park Service lands to Samuel P. Taylor State Park until the completion of the project, when it is once again safe for use by hikers, equestrians, and cyclists.    

The Cross Marin Trail meanders along the old North Coast Pacific Railroad grade which once ran between Larkspur to Cazadero. The trail is paved for a portion and runs through Samuel P. Taylor State Park on California State Park lands where users can stroll or bike along majestic redwood trees adjacent to Lagunitas Creek, home to endangered coho salmon and steelhead.