The problem is that all those fixes require money and time.
A $330 million project for Bound Brook is not yet complete, and showed some of the limitations of the flood mitigation project. For one thing, the flood control project planned for a 150 year event, and Irene was a 500 year event (but expect that kind of storm damage to become more common place).
Heck, they usually require planning and it turns out that a New York State Panel empowered in 2006 to look at flood fixes for the Mohawk River near Albany never met.
A task force created to find ways to lessen water damage after a 2006 flood hit the Mohawk Valley and the state canal system has never met despite a state mandate. Flood damage in the wake of Tropical Storm Irene raises questions about the failure to develop a plan that could have reduced losses this summer.Plans for a water diversion tunnel in New Jersey that would shift water from the Passaic River to Newark Bay have been floated several times, and there was even money set aside for that purpose, but environmentalists ended up killing the tunnel.
Population density is part of the problem within the Passaic watershed. There's far too many properties within the flood plain and flooding is complicated by runoff from more developed areas. Buyback plans to condemn and demolish homes and businesses in the worst flooding areas are nearly tapped out; these areas soak up floodwaters and reduce downstream flooding.
Some localities have called for dredging of waterways that have become choked with silt from runoff but environmentalists block such moves on grounds that it is a temporary solution, or that it will disturb polluted areas releasing more contaminants into waterways, etc.
Flood control projects meant to protect downstream areas get blamed for upstream flooding, which becomes a contentious issue as political disputes end up blocking any action at all - and these issues require interstate and regional solutions since watersheds often cross political boundaries.
Areas upstate are considering the unthinkable - instead of rebuilding along the same streams and waterways that have flooded several times in recent years, they are contemplating moving to higher ground and moving all the infrastructure that goes along with it. There are also calls for no new development within the Catskill watershed (which includes the NYC water supply area) and other efforts to reduce flood damage by moving structures out of projected flood areas.
Such plans wont help places like New York City, where much of the area is within a flood zone including Lower Manhattan.