The Prairies Ecozone has almost entirely been taken over by agriculture, with only 13% of the shortgrass prairie, 19% of the mixedgrass prairie, and virtually none of the tallgrass prairie community remaining. With so little remaining original land, many Prairie species are threatened. In contrast, many pest species are introduced to the region and flourish with the large expanses of a single food source. With all the farming comes soil erosion which gets in to water and can destroy aquatic ecosystems. Also extraction of water from rivers and watersheds can lead to a drier local and regional climate.