The Oregon Garden in Silverton, Oregon. With help from the City of Portland and the non-profit EcoRoofs Everywhere, the Oregon Garden built its first green-roof on June 12, 2004. Housed on a filter pump station that is set into the side of a hill, the roof allows Garden visitors an up close look at the construction and plants on the roof. The roof is divided into several plots with different growing media, which is one of the critical factors in green-roof success, according to the latest research. A mix of drought-tolerant plants grow on top of the building. Eco roofs can perform many environmental benefits: reduction of storm-water run-off, improvement of water quality of roof run-off; replacement of habitat lost when the structure was built, reduction of energy costs inside the building and extension of the roof's life-span.