Popo Agie River

The Middle Fork Popo Agie River is a river in Wyoming in the United States. The river is 54 miles long. The river is sometimes referred to as simply the 'Middle Fork'. The river is part of the Popo Agie Watershed and from its headwaters in the Wind River Range until it joins with the North Fork of the Popo Agie River, the river and its tributaries irrigate roughly 11,503 acres. The river is notable for passing underground through a sinkhole in Sinks Canyon State Park, only to emerge several hundred yards downstream at "the rise." The ground distance is not far, but tests with dye have shown it takes the water many hours to flow through the underground passage. ​