With Funding Tight, Cities are Turning to Green Infrastructure by Jim Robbins: Yale Environment 360.

A 2012 studyby American Rivers, ECONorthwest, and other groups examined 479 projects around the country. About a quarter of the projects were more expensive, they concluded, and 31 percent cost the same; more than 44 percent brought the costs down, in some cases substantially. New York City, for example, expects to save $1.5 billion over the next 20 years by using green infrastructure.