Flowing past Montezuma Castle is Beaver Creek, one of several perennial streams that make their way into the Verde River. Beaver Creek provided the water necessary for the prehistoric inhabitants of the Castle in an otherwise arid landscape devoid of springs or other sources of water. Beaver Creek is comprised of two watersheds, Wet Beaver and Dry Beaver. Wet Beaver Creek has as its source a series of springs at the base of Hog Hill, a part of the Mogollon Rim. These springs, and most of the length of the creek, are protected in the Wet Beaver Wilderness, a 6,700 acre wilderness area established by Congress in 1984. The upper reaches of the creek slice through the southern edge of the Colorado Plateau, creating a narow canyon with few access points. The canyon opens up as the creek leaves the Wilderness and flows through rolling hills as it passes through Montezuma Well Detached Unit of the monument. A few miles downstream of the Well the creek joins Dry Beaver Creek. While the drainage area of Dry Beaver Creek is much larger than the watershed of Wet Beaver Creek, there are no springs providing for a permanent flow. The annual median flows of 22,000 acre-feet for Wet Beaver Creek and 21,000 acre-feet for Dry Beaver Creek combine to create the flow of Beaver Creek as it passes by the Castle before its confluence with the Verde River. The creek provides habitat for native species of trout and sucker, and non-native species such as bass, catfish, and carp.