States pledged to slow harmful sprawl by 30 percent when signing the Chesapeake 2000 agreement. To track sprawl, the Chesapeake Bay Program adopted impervious surfaces as its new measurement of "harmful sprawl."

Impervious surfaces like roads and rooftops prevent rainwater from naturally entering soils, and rapidly transfer pollution to local streams. Impervious cover increased in acres between 1990 and 2000. Reducing the rate 30 percent will save many acres from becoming impervious.

The new indicator, "Chesapeake Bay Watershed Development Trends," can be viewed at the Chesapeake Bay Program website.

7/30/2004