Across the nation, countless cities with antiquated sewer and stormwater systems are under orders from the U.S. Environmental Protection Agency (EPA) to reduce stormwater runoff to decrease the amount of pollution entering local waterways. When Washington, D.C., faced this problem, city officials decided to experiment with green infrastructure rather than investing in expensive new pumps and pipes. Since green infrastructure had never been implemented on such a large scale, however, the city faced a huge challenge when it came to financing the project.