Bolinas Lagoon

 lake, wetland, nature conservation park / area, Ramsar site

Our earliest geologic maps (1850s) show an island-free Bolinas Lagoon, which was navigable to the far northern end by shallow-draft vessels.
Today the far northern end is not accessible by any watercraft and the main body of the lagoon is navigable only by canoes and kayaks (and only during high tide, at that.) Shallow-draft boats with outboard motors can use narrow channel near the mouth of the lagoon at high tide.
Between 1968 and 1988 the lagoon lost twenty-five percent of its tidal prism (water volume capacity, over one million cubic yards) from sedimentation. In the past 30 years, the "upland" areas (dry land) surrounding the lagoon have increased by 67%. During this same period, the sub-tidal areas (deep water) have decreased by 29% and the inter-tidal (mudflats) by 5%. The sub-tidal and inter-tidal areas are where the ecological value of the lagoon is most significant.
Activities causing the increase in sediment buildup include grazing, tree harvesting, farming, re-routing a stream, and creating a recreational "inner lagoon" by dredging and disposing the dredge "spoils" into natural Bolinas Lagoon. Since the lagoon's destruction is being caused by human interventions, it is appropriate that the lagoon be restored and preserved by human intervention.
In 1996 the Congress directed the U.S. Army Corps of Engineers to undertake an evaluation of Bolinas Lagoon and determine whether there would be a federal government interest in preserving the lagoon as a functioning tidal estuary. The Corps decided that there was a federal interest in preserving Bolinas Lagoon's habitat values and in 1998, in a joint venture with Marin County, undertook a multi-year restoration project )the first such project in Corps history justified solely by the ecological values to be preserved and benefits to be derived.)