EPA on water resources and development
Earlier this year EPA released a series of long-awaited publications on water resources and development patterns (see the March 2006 New Urban News). A review of one of those publications, Protecting Water Resources with Higher-Density Development, shows it was worth the wait and must not be ignored by environmentalists and planners. It presents the clearest case to date why small lot development, with higher impervious cover on a percentage basis of the lot, is much better for watersheds. Three scenarios are explored: A) one-acre lots with 20 percent impervious cover; B) quarter-acre lots with 38 percent impervious cover; and C) eighth-of-an-acre lots with 65 percent impervious cover. “Each house in scenario B produces approximately 67 percent less runoff than a house in scenario A, and each house in scenario C produces 74 percent less runoff than a house in scenario A,” according to the report.
The booklet illustrates a series of examples that show what happens when these three scenarios are played out over entire watersheds — the results are dramatic. After 40,000 scenario A houses are built in a 20-year period, four watersheds are consumed. After 40,000 scenario C houses are built, one half of one watershed is consumed. Note that scenario C houses are typical — perhaps even a bit larger than average — single family lots in a new urbanist development. So, to get substantial benefits to water resources, every house does not have to be an attached or multifamily unit. In fact, a range of lot sizes and housing types, including some larger lots, would meet the criteria. Free copies are available by calling 800/490-9198. Electronic versions are available at www.epa.gov/smartgrowth.
