A major flood insurance bill was a rarity when it passed what is widely derided as a do-nothing Congress in 2012, but a year and a half later, there is now an enthusiastic bipartisan effort to gut it. This week the Senate is expected to approve a measure that would block, repeal or delay many of the key provisions of the Biggert-Waters Flood Insurance Reform Act, which was sponsored by Representative Judy Biggert, an Illinois Republican, and Representative Maxine Waters, a California Democrat. Tucked into broader transportation legislation, the bill had enthusiastic support across the political spectrum, from liberal environmentalists...