American Canyon resident Beth Eiess has driven 21-mile-long Highway 37 from Vallejo to Novato and sees the weak points, such as the congested, two-lane segment over the Napa-Sonoma marshes.

“The commute can vary from a half-hour to two hours, depending on congestion,” she said at an open house on the future of Highway 37.

Transportation officials are looking for Highway 37 solutions. One plan is to turn the nine-mile, two-lane section over the marsh into a four-lane road.

Another Highway 37 challenge is sea level rise that studies predict could swallow sections of road by mid-century and virtually all of it by century’s end. Eiess’ 10-year-old daughter Savannah suggested building bridges over the low sections.

Transportation officials are thinking along the same line. They are exploring the creation of an elevated Highway 37, perhaps putting the road on a embankment or causeway.

They say a toll — perhaps $6 or $7 — may be needed to pay for the project, given the costs for various types of raised roadways could range from $1.4 billion to $4.4 billion in 2030 dollars.

Savannah is hesitant. “A lot of people don’t have enough money to pay the toll,” she said.

The Highway 37 rescue plan road show came to American Canyon City Hall on Sept. 27. Beth Eiess and Savannah were among those attending to both learn and voice opinions – and, in Savannah’s case, to earn an Inside Government badge for Girl Scouts.

Sponsors were the Napa Valley Transportation Authority, Caltrans, Metropolitan Transportation Commission, Solano Transportation Authority, Transportation Authority of Marin and Sonoma County Transportation Authority.

Chris Benz of the Napa Sierra Club attended the open house. She said mass transit should be included with the Highway 37 improvement plans, perhaps a ferry service from Vallejo to Marin County.

“We think if you just expand the roadway, you won’t decrease traffic,” she said.

Others have voiced similar opinions about road widening projects in general. The national Sierra Club website has articles claiming that merely adding highway lanes spurs more driving and development, leading to more congestion.

Benz also said that the Highway 37 plan must protect the adjacent marshes and wetlands. She views them as a flood buffer.

“That is our protection in Napa from storm surges,” she said.

Kristin Tremain Davis of Benicia attended the open house. She works for AECOM, the firm doing environmental work for the Highway 37 project.

To Davis, the trip along Highway 37 through the Napa-Sonoma marshes is more than a blur of tules and wetlands. She said these marshes are home to such rare creatures as the Ridgeway’s rail, California red-legged frog and salt marsh harvest mouse.

Also, these marshes are a stopover for migratory birds on the Pacific Flyway, she said. The Pacific Flyway is an avian route for millions of birds extending from Alaska and Canada to Mexico.

Davis sees the Highway 37 project as a chance to benefit not only drivers, but also the environment.

The newly released, draft Highway 37 Transportation and Sea Level Rise Corridor Improvement Plan goes into more detail about Highway 37 challenges and potential solutions. It was done by consultants Kimley-Horn.

This plan cites a study by the University of California, Davis, that predicts sea level rise of 36 inches by 2100 will leave much of the roadway permanently under water. Some sections, such as near Mare Island, could go underwater by 2050.

Storms already flood parts of Highway 37, such as this past winter, when a stretch near Novato Creek was closed for 28 days, the Highway 37 plan said.

The primary cause of congestion is that traffic exceeds capacity along the two-lane segment from Mare Island to Sears Point, the plan said. No public transit is available to reduce demand, it said.

Possible strategies listed in the plan fall into three categories: retreat, protect and accommodate.

Retreat means closing Highway 37 permanently if and when sea level rise floods it. But alternative routes such as Highway 29 and Highway 121 in Napa County don’t have enough capacity. Nor can train or ferries carry all of the Highway 37 traffic, the plan said.

Protect means raising levees and taking other flood protection steps, such as raising some sections of Highway 37 at low spots.

Accommodate means building a causeway above the projected, future limits of high tides, storm surges and waves. A cheaper alternative is to build a new highway on an embankment.

“All the new structures will consider species migration,” the Highway 37 plan said. “Center barriers on embankment sections will have openings for animal crossings and/or additional culverts to improve species migration.”

Some short-term steps can be taken to ease Highway 37 problems, the plan said. One is improving the Highway 121 intersection at Sears Point. Another is making levee and other flood protection improvements that could protect Highway 37 through 2050.

Beyond 2050, the roadway will likely need to be raised because the scale of levee and shoreline improvements needed would likely be infeasible, especially for the segment from Sears Point to Highway 101, the plan said.

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Napa County Reporter

Barry Eberling covers Napa County government, transportation, the environment and general assignments. He was worked for the Napa Valley Register since fall 2014 and previously worked 27 years for the Daily Republic of Fairfield. He is a graduate of UC Sa