As part of the Napa River/Napa Creek Flood
Protection Project, Napa County Flood Control
and Water Conservation District has been
investigating the distribution of the rare plant,
Lilaeopsis masonii, in the lower reaches of the
Napa River and Napa Creek ecosystem. From
2001–2010, annual Lilaeopsis masonii
monitoring in all impacted stream reaches was
conducted and population trends were analyzed.
Results indicate a very robust Lilaeopsis masonii metapopulation on the Napa River; this rare plant species colonized and flourished in the newly created habitat on the restored Napa River floodplain. The final 2010 monitoring year documented 118 Lilaeopsis masonii occurrences with total combined square footage of 8,963 sq. ft., well above the targets established by CDFG of 69 occurrences across 4,036 sq. ft.