A study in Rockville, Maryland, tested how a green roof, wetland, and garden setup on a house managed stormwater over 2 years. They found that these systems stored about 36.4% of rainwater from 116 storms. The wetland was the best at holding runoff, keeping around 37.6% of the water. The size of the storm was the most important factor affecting how much water was kept. This research shows that using these green systems together can help control stormwater in residential areas effectively.