Teton Creek drains from the rugged Teton Range in the Grand Teton National Park west into Idaho. This area is known for breathtaking scenery and incomparable recreational opportunities. The town of Driggs, at the base of the Grand Targhee Ski Resort, has grown rapidly to accommodate new residents and visitors. A large subdivision was developed in 1980 within the active floodplain of Teton Creek. Almost annually over the period of 20 years, to protect houses from flooding, the developer used heavy equipment to close-off and fill-in secondary channels and to channelize 4,000 feet of the stream. Channelization included straightening, dredging and widening of the main channel and extensive removal of riparian vegetation. The developer lowered the streambed 4 to 8 feet, increased the stream width from 50 to 100 feet, and removed acres of mature cottonwood trees. A headcut migrated upstream for half a mile, resulting in incision and lateral instability. Excessive sediment was deposited downstream over 2.5 miles of stream, causing aggradation and streambank failure.
For the Friends of the Teton River (FTR), a local environmental non-profit organization, and Teton County, ID, AESI collaborated with Mainstream Restoration and Biota Research and Consulting to provide design and construction assistance to restore 6,100 feet of stream. AESI worked collaboratively with Mainstream Restoration and Biota to take the project from concept to final design. AESI served as the Engineer of Record providing hydraulic modeling; grading design; and assistance with stream restoration design. The team prepared construction-ready plans and specifications, a design report and cost estimates. The design consisted of a stream channel set within 5 acres of newly shaped inset floodplain designed to convey the 100-yr flood. The project involved extensive earthwork (50,000 cubic yards of cut/fill); a variety of bank protection using woody material; constructed riffles to maintain grade; woody material anchored across the new floodplain to slow water velocity and create habitat; and revegetation of the inset floodplain using salvaged soils, seed and propagules.