At the mouth of Grindstone Creek lies the expansive Grindstone Estuary, a 60ha coastal wetland and floodplain marsh owned by the Royal Botanical Gardens (RBG). Floodplain wetlands, like many of the vegetation zones on RBG property, are one of the most threatened habitats in Southern Ontario. Many years of poor watershed management and infilling (filling in the wetland with material) have altered the natural flood cycle and created poor quality floodwater, further promoting floodplain degradation. This degradation of the natural environment allowed for the invasion of non-native species, e.g. Asian carp, round gobies and zebra mussels. When Project Paradise began in 1993, 85% of the marshland had been destroyed by carp, leaving behind a series of shallow muddy ponds. Today, a number of small carp barriers and man-made river banks restrict these invasive fish, allowing nature to successfully restore the area to a marshland.