certs and other events; Sam Bush played in the Amphitheater in 2006. Gordon House, the only house Frank Lloyd Wright designed in Oregon, is now on the grounds of Oregon Garden. The house, designed in 1957, is one of Wright's Usonian houses, and the only Wright house open to the public in the Pacific Northwest. Completed in 1964, the home was moved from Wilsonville, Oregon, to the garden in 2001. On each Earth Day since 1999, the Garden hosts a celebration which attracts environmental supporters and organizations with demonstrations, exhibitions, and workshops. Garden admission is free for this event. Using treated wastewater from the city, the garden is one of only a few installations in the United States that reuses wastewater for a water feature. Even in the summer months, the garden does not draw on drinking water supplies, instead relying entirely on wastewater treatment plant effluent, which additionally irrigates 240 acres (0.97 km2) of farmland. Until recently, such use was prohibited by state law, but the law was revised partly due to this water reclamation project. The garden also provides wetland mitigation for a nearby industrial park to provide waterfowl and amphibian habitat, and offloads Silver Creek from water it would not naturally carry during low-flow months in the summer to address an Oregon Department of Environmental Quality requi