Washington state will begin requiring municipalities to use "rain gardens" and pervious pavement in new urban developments to combat rainwater pollution to the state's rivers and lakes and to the Puget Sound, officials announced Wednesday. The new "low-impact development" practices will be phased in over the next few years in an attempt to minimize the fiscal impact on local governments, the state Department of Ecology said. "Storm water is the No...The requirements will be in use by June 2015 in Seattle and Tacoma, as well as King, Snohomish, Pierce and Clark counties. That will be followed with less populated areas, which will begin employing the new standards by the end of 2016...Eastern Washington communities will be required to follow the new low-impact practices by the end of 2017. Rain gardens are planted depressions featuring soil and shrubs that allow rainwater runoff to soak into the ground. Pervious pavement also allows runoff to filter into the soil. "It's a whole lot easier and cheaper to prevent runoff and pollution as we plan our developments, than to try to manage storm water after the fact," Sturdevant said. Rain runoff that's not absorbed tends to pick up pollutants as it makes its way into streams, then into rivers, lakes or the Puget Sound. Under the new initiative, the state will monitor how the new practices work, and check to see whether pollutants in Washington's waters are decreasing, Sturdevant said. "It's been a long process, 15 years for me," said Bruce Wishart of People for Puget Sound. Washington is "transforming the way we do development, moving into these green building techniques."