Description - Sinks Canyon is so named because the Middle Fork of the Popo Agie, a rushing mountain river, flows out of the Wind River Mountains and through the Canyon. Halfway down the canyon the river abruptly turns into a large limestone cavern, and the crashing water "sinks" into fissures and cracks at the back of the cave. The river is underground for 1/4 mile until it emerges down canyon in a large calm pool called "The Rise" and then continues its course into the valley below. Where the water goes while it is underground is unknown. The sinks narrow to small, unexplorable log and rock jammed fissures. The Sinks and Rise occur in the thick, easily eroded off-white Madison Limestone formation. The amount of water flowing into the Sinks varies with the season. The average amount of water in the river is 150 cubic feet per second. During spring run-off over 500 cubic feet of water per second roar down the rocky Popo Agie River channel. For many years it was unproven that the water flowing into the Sinks was the same water flowing out at the Rise. Dye tests have proven it is the same water but have revealed other mysteries: it takes the water
flowing into the Sinks over two hours to reappear at the Rise. Geologists speculate that while underground the water circulates up and down and through many narrow, winding passages and pools until it resurfaces. It was also discovered that more water flows out at the Rise than goes in at the Sinks. The additional water may be coming from underground springs or other sinks formations in the area. It is unknown exactly how old the Sinks are although they are likely an Ice Age feature thousands of years old. The massive glaciers that carved the canyon exposed the soft limestone and the millions of gallons of water from the melting ice helped erode the underground passages. Native Americans knew of the Sinks for generations. The first white men to see them were fur trappers in the early 1800s.
- Famous for the mysterious Sinks and Rise and its spectacular geology, Sinks Canyon is the home to a myriad of wildlife, birds and plants. Three major habitats are readily observed in the canyon and each is unique.
The Sinks Canyon State Park Visitors Center is open seven days a week 9 a.m. to 7 p.m. Memorial Day weekend through Labor Day weekend. There are displays about the ecology, wildlife and the history of Sinks Canyon including interactive displays and a "kids corner." "The Raptor tree," glacial geology, mounts of bison, elk, deer and bighorn sheep are some of the displays located in the visitors center. Short interpretive hikes are available around the center.
State Park employees are in the center to answer questions. In addition, there are videos on the canyon, Wyoming's Wildlife, history, and other attractions are shown. The Visitors Center host the Sinks Canyon Speakers series throughout the summer. Weekly programs on wildlife, geology, history, and botany, are given by experts. Bighorn Sheep, bears, The Oregon Trail, canyon geology, Mushrooms and the Mountain Man, have all been topics in past programs. Call the Visitor Center for information on this summer's programs at (307) 332-3077.
Recreation - Recreational activities in the park include hiking, birdwatching, picnicking, camping, fishing, relaxing and rock climbing.
Climate - Three major habitats are readily observed in the canyon and each is unique. The most dramatic contrast in habitats is between the heavily forested north facing slope and the drier sagebrush and juniper covered south facing slope. The north facing slope is in the shade much of the winter allowing heavy snow to accumulate. This snow provides the moisture needed for the tall Limber Pine and Douglas Fir trees. The south facing slope receives a great deal of sunshine all winter which melts the snow quickly. This lack of snow makes this slope an excellent winter range for many animals because they don't have to struggle through heavy snow to find food. Another habitat in Sinks Canyon is the Riparian zone along the Popo Agie River. This is the moist area along either side of the river where there is enough water to support thick stands of Aspen, Chokecherry and Willow. The moisture in the Riparian zone allows wildflowers such as Sticky
Geranium, Yellow Monkeyflower and Columbine to flourish. All of these habitats make Sinks Canyon a rich place to observe nature, and the surrounding National Forest and wilderness areas extend the opportunity to experience Wyoming's beauty at its best.
Sinks Canyon is located 6 miles south of Lander on Highway 131.