As every homeowner knows, water flows in mysterious ways. A small crack in a gutter in one place may lead to an interior leak and water damage two rooms over and a floor below. In much the same way -- though in a positive sense -- an ambitious, broad-scale initiative by the city of Philadelphia to address major stormwater-system deficiencies is seeping into many avenues of reform and creativity, with payoffs far beyond its fulfillment of a federal consent decree.

In this space back in 2010, I described the $8 billion plan being reviewed by the Environmental Protection Agency to meet Philadelphia's obligations an environmental problem faced by many older cities that have combined sewer and stormwater systems: During heavy rainfall, the stormwater that normally flows through a water-treatment system overwhelms it, releasing raw sewage and filthy urban stormwater into rivers and streams.

Instead of a massive underground retention tunnel, Philadelphia proposed a comprehensive approach that would slow stormwater as it hit the ground, capturing it in myriad purpose-built basins, stormwater wetlands, green roofs and vastly expanded permeable surfaces converted from the concrete that dominates urban development. The EPA approved the plan in 2012 and the lead agency, the Philadelphia Water Department, reports regularly on incremental progress in achieving milestones necessary to retain EPA approval of the plan.

At its heart, the EPA-pproved plan is all about hydraulics and engineering. What interests me here, though, is how the city's implementation of its Green City, Clean Waters plan has nurtured a significant community movement as well. Stormwater-management imperatives -- executed with the deep engagement of communities and schools -- have multiplied the benefits of changing out dreary concrete and asphalt surfaces by making environmental education an integral part of the planning and implementation of rebuilt school and recreation-center playgrounds. This aligns perfectly with the city's goal of bringing a green park (not a concrete playground) within 10-minute walk of every Philadelphian. And in turn, community education and involvement has built support for a daunting project affecting virtually every city resident and business.

The belief that community involvement would yield cooperation and long-term stewardship of new green spaces continues with new partners that include the Philadelphia School District, the Parks and Recreation Department, and numerous community organizations. The Community Design Collaborative, a network of more than a thousand design volunteers, has worked with 18 Philadelphia public schools to produce detailed plans, some of which have been completed, others for which fundraising is underway. The work and a roadmap for future communities is captured in a collaborative design guide.

This structured process begins with organizing stakeholders and laying the groundwork for classroom and neighborhood participation in design and, later, educational use of newly greened areas. These planning processes are where the engineers meet citizens with their own ideas, where teachers find opportunities to step out of the classroom with students who may have had little exposure to earth in its natural state, and where a circle of engaged people learn together and negotiate what they believe best for their own spots of community.

These are not inexpensive projects. They require smart financial leveraging across multiple funding sources. The arrival of the Trust for Public Land to Philadelphia in 2010 provided a significant boost to the nascent green-schoolyards initiative. With experience in "greening" 185 schoolyards in New York City through partnerships with various city agencies, the trust brought the expertise to wrestle with the complex interdepartmental legal, financial and technical hurdles that stall the best of plans and test community patience. Philanthropic dollars are raised to combine with school-district and city capital funds, as well as financial incentives offered by the Water Department for removal of impervious surfaces.

The trust has five schoolyards in underserved areas underway and a goal of 20 within six years. The growing pipeline of community-based plans for transforming school and rec-center playgrounds has combined cutting-edge engineering solutions with community revitalization opportunities. It's a payoff for Philadelphia that goes far beyond merely getting unruly stormwater under control.