Lake Dalwigk

Efforts to extend the shorelines of Mare Island and Vallejo — narrowing the Napa River channel between them — date to the earliest days of the city and the Navy’s first West Coast shipyard. Old navigation charts show the Navy, which began operating Mare Island Naval Shipyard in 1854, quickly filled in a strip of marshland along the river and constructed a seawall or quay where ships could tie up.

On the Vallejo side, expansion into the Mare Island Strait added nearly 500 acres along the waterfront, from near the Highway 37 bridge on the north side of Vallejo to the old Sperry Mill site in South Vallejo.

One ambitious project filled in a wide section of river that once separated Vallejo from south Vallejo. The new land was formed in the early 1900s by establishing a barrier that ran straight from what’s now the city boat ramp almost to Lemon Street in south Vallejo. Mud dredged from the river on the west side of the barrier — or bulwark — was then pumped into what once had been navigable water and tideland on the other side. The dredge-and-fill process that began on a large scale in 1913 took several years, creating more land and more direct road links between the two communities. Present-day Sonoma Boulevard between Curtola Parkway and Lemon Street would not exist without this project. The same goes for the wastewater treatment plant, the Kiewit Pacific Co. yard on the river, and many other businesses. The river spread as far east as Fifth Street, where it turned into a marshy connection to Lake Dalwigk. On the south side, the railroad tracks that cross Fifth Street near Solano Avenue once ran along the water’s edge into south Vallejo.

There’s a similar situation near Lake Dalwigk on the south side of Vallejo, where many homeowners in nearby neighborhoods must have sump pumps in basements. Old maps show marshy areas and a small creek extending south and east toward Magazine Street. Sump pumps also are needed in other areas, including parts of Vallejo’s historic downtown, due to underground streams, springs, subsurface infiltration of river water and other sources. (Many thanks to Vallejo historian Brendan Reilly for the information above.)

Today, Lake Dalwigk serves as a critical flood control basin for the southern parts of the city. In 2012, Vallejo Flood & Wastewater District significantly increased the lake's capacity and improved wildlife habitat by deepening channels and creating lakes there, reestablishing the flood protection the lake provided when it was originally created. In 2018, the District partnered with the Solano Resource Conservation District, the Greater Vallejo Recreation District, and the Vallejo Watershed Alliance on a major habitat restoration project. More than 200 native California trees, countless wildflowers and grasses, and many shrubs were planted. The project also included a new drinking fountain, pet waste stations, and interpretive signs. Planting currently continues, as do regular lake trash cleanups. If you would like to volunteer for these or other activities, please visit Vallejo Watershed Alliance or email Info@VallejoWatershedAlliance.org.