It starts at the confluence of the Middle and North Forks of Ahtanum Creek near Tampico, flows along the north base of Ahtanum Ridge, ends at the Yakima River near Union Gap and forms a portion of the northern boundary of the Yakama Indian Reservation.

[4] Native Americans, including the Yakama Tribe inhabited the region surrounding Ahtanum Creek long before the arrival of Europeans.

The original mission was burned down in 1855 during the Yakima War by U.S. soldiers who believed the missionaries were conspiring with the Yakama Tribe.

[9] Water is pulled from Ahtanum Creek to irrigate 9,000 acres (36 km2) of land upstream of the gauge in Union Gap.

[12] Being located in the rain shadow of the Cascade Range, Ahtanum Creek has a riparian zone that serves as an important habitat for animals living in the region.

This project included strengthening three areas of the creek bank that were prone to erosion and reintroducing native plant species such as coyote willow.

These changes reconnected that stretch of the creek with its flood plain and provided areas for young fish to be reared.