While regional agencies weigh a proposal to raise a floodprone stretch of U.S. Highway 101 between the Manzanita park-and-ride and Donahue Street in Marin County, a local scholar has explored an alternate vision: putting the freeway in a tunnel beneath a new linear park. The two views highlight the stakes for Marin City, a lowlying community that is already likened by experts to a bathtub with an inadequate drain as sea levels rise. There is currently a preliminary plan to elevate Highway 101 from Manzanita to Donahue at a rough estimate of $1.2 billion, with an extra $33 million for stormwater pumps and a drain pipe to carry rainwater beneath a shopping center that sits on slightly higher ground between Marin City’s entrance road and Richardson Bay.

Other flood planning news:

• Manteca Bulletin (Calif.): Cantu slams home plans in 200-year floodplain ahead of levee work