Point Reyes Light - December 7, 2000
Decision on dredging Bolinas Lagoon bogs down
By Gregory Foley
With the US Army Corps of Engineers several months behind schedule, the Marin Open Space District last week announced that a decision on where dredging will be done in sediment-choked Bolinas Lagoon has been put off until early next year.
The Open Space District, which is the owner and primary manager of the 1,100-acre lagoon, at two meetings last week in Stinson Beach and Bolinas introduced a revised list of nine alternatives for removing sediment and fill from the estuary to increase tidal capacity and improve fish and wildlife habitat.
Supervisor Steve Kinsey, a member of the Bolinas Lagoon Restoration Project Executive Committee, last Thursday in Stinson Beach encouraged a crowd of 50 residents to back the restoration effort. "A project of this scale and magnitude can only move forward with broad support from the communities," he said.
Panel behind schedule
The nine alternatives were distilled from three years of research conducted as part of a $2-million Feasibility Study by the district and the Army Corps.
In August, the Habitat Evaluation Panel – ten scientists and naturalists from a variety of public agencies and non-profit organizations – refined a previous list of six separate alternatives and five combinations thereof.
The panel, which includes Audubon Canyon Ranch biologist Greg de Nevers, Gulf of the Farallones National Marine Sanctuary Manager Ed Ueber, and state Fish and Game biologist John Mello, has continued – beyond its schedule – to evaluate the choices before recommending an environmentally-acceptable course of action to the Corps.
Cindy Bowen, project planner for the Corps, explained to the crowd that efforts are being made to get the project back on schedule. "The next panel meeting will take place in January to finalize the options," she said. "After that we can proceed with the environmental impact analysis."
Army Corps engineer John Winkelman presented the nine alternatives, which are designed primarily to restore the lagoon’s tidal flow to where it was in the mid-20th century. The alternatives are:
• Seadrift Lagoon – Four variations include: Open the small lagoon within the Seadrift subdivision to tidal flooding by enlarging the culvert systems at the east and west ends; create two 20-foot open channels to promote tidal exchange; open only the northwest end of the Seadrift Lagoon to tidal flooding; and making no changes to Seadrift Lagoon.
• South Lagoon Channel – Dredge two new channels to connect the main channel (in the central part of the lagoon) to the eastern culverts of Seadrift Lagoon.
• North Basin – Lower the lagoon floor by up to two feet in the northern end of the lagoon to increase intertidal and subtidal habitat, which have been significantly reduced in the last 30 years. The project would also serve to maintain the main channel, which flows around Kent Island.
• Main Channel – Deepen four sections of the existing channel and remove a small island of sand and sediment east of Kent Island. This project would improve the flow of seawater to the north end of the lagoon.
• Bolinas Channel – Dredge sediment from the channel that runs between Kent Island and the Bolinas waterfront along Wharf Road. The new channel would run from the lagoon inlet to the Pine Gulch Creek Delta east of Bolinas-Stinson School.
• Highway 1 – Remove unnatural fill along the lagoon’s eastern shore in up to 10 areas that currently constitute unpaved gravel turnouts, fill disposal sites, and excessive shoulder material dumped over time by Caltrans. The main spots would be at the northern and southern ends of the lagoon.
• Dipsea Road – Remove fill along the east side of the Seadrift subdivision along Dipsea Road.
• Kent Island – Cut a 200-foot-wide channel through Kent Island to restore a pre-existing channel last evident in photographs from the 1940s. The project would also involve dredging three 75-foot-wide channels through the island and reducing its overall elevation by up to two feet.
• Pine Gulch Creek Delta – Remove sediment at the delta of Pine Gulch Creek up to the border of the proposed North End Basin.
Ron Miska, Open Space planning and acquisition manager, explained last week that he believes that the panel will eventually recommend a combination of the choices, which will no doubt be further refined as the final project is designed. "I would sincerely doubt that the study would be finished with just one alternative," he said.
Additional alternatives may evolve from an Army Corps Watershed Study that is now underway, Miska noted.
Mouth closed by 2035
The Corps’ studies of the lagoon – which in 1998 was designated as a "wetland of international importance" by the US Fish and Wildlife Service – have estimated that the lagoon mouth could close intermittently by 2035 if nothing is done about the sedimentation.
Between 1968 and 1998, the Corps estimates that the lagoon’s upland habitat – that is, land which is always above water – increased from 158 acres to 264 acres.
Also, 40 acres of tidal habitat has been lost, while the sub-tidal habitat – that which is always below water – has decreased from 222 acres to 158 acres.
Project engineer Winkelman explained last week that recent samples from the lagoon floor show that the majority of the sediment has been carried to the lagoon by creeks in the roughly 16-square-mile watershed.
Earlier studies by the US Geological Survey have suggested that a higher percentage of the sediment originated from the eroding cliffs near Bolinas and was washed in through the lagoon’s mouth.
Logging & grazing
Many researchers including Winkelman believe that the problem has been exacerbated by logging and grazing in the coastal hills in decades past, as well as by development along the lagoon edges, such as the construction of Seadrift subdivision.
"It appears that most of the sediment was coming from the watershed and still is," Winkelman said. "The sedimentation rate has dropped off exponentially since 1968, and the last logging in the area was in ‘68 and ‘69. If the sediment was primarily deposited from the ocean you wouldn’t expect to see that change."
If all nine alternatives were implemented, Winkelman explained, roughly 1.52 million cubic yards of material would be removed from the lagoon’s floor and shoreline.
However, some Stinson Beach residents, particularly those living in Seadrift, questioned the Corps representatives on their ability to predict the consequences of such a large project. "I think all the Seadrift people are worried about the work on the Seadrift Lagoon and the South End," said Ed Cutter of Stinson Beach.
Adaptive management
Gordon Bennett of Muir Beach, Conservation Committee co-chair for the Marin Sierra Club, asked that the Corps adapt the work as it goes, based on what’s happened after any previous work. "We get the feeling that the Army Corps of Engineers wants to just get the job done and get out," he said.
Skip Schwartz, executive director of Audubon Canyon Ranch, agreed the project should be studied and adapted as it goes. "I think it’s the only way to go, " he said. "In my knowledge, there’s never been a project done like this before."
After a course of action is agreed upon, Corps engineers will start designing the work. Open Space officials estimate that formal environmental review of the estimated $20-million project will be completed by April 2001. The actual dredging and removal of fill – if done at all – is scheduled to begin in 2004.
Tim Haddad, environmental planning coordinator for the Marin Community Development Agency, explained that the public will have several opportunities to comment on the plan as it progresses over the next year through the county Planning Commission and the Parks, Open Space, and Cultural Commission.
Marin supervisors, acting as directors of the Open Space District, could be voting on the EIR possibly by the end of next year, Haddad said.