Federal plan would add upstream detention dam, channel armoring and a flood wall to reduce Gold Wash flooding

The Hurricane City Council heard a technical briefing on flood-control alternatives for Gold Wash from Bobby Preet of Adaptive Environmental Planning, the consultant working for the Natural Resources Conservation Service. The project is part of a federally funded effort under the Watershed Protection and Flood Prevention Act to reduce flood risk mapped by FEMA in 2009.

"This project is intended to help reduce that flooding, and benefit the community as a whole," Preet told the council, describing the planning-phase work and a forthcoming draft plan environmental impact statement that will include a 45-day public comment period.

Preet said project engineers evaluated 18 alternatives and identified two that met feasibility and permitting criteria. The preferred approach relies on a dry detention (debris) basin on Bureau of Land Management property above the Hurricane Cliffs to attenuate flows during major storms, reducing modeled peak flow over the cliffs from roughly 8,800 cubic feet per second to about 3,000 cfs entering the channel downstream.

Downstream channel work would combine riprap-armored trapezoidal channel segments and, where velocities are very high, an engineered flood wall. Preet said the U.S. Army Corps of Engineers has reviewed the alternatives and determined the preferred option meets the LEDPA (least environmentally damaging practicable alternative) requirements for permitting.

The plan would require replacing two culverts in town and obtaining easements where the city channel currently lacks rights-of-way. Preet emphasized that most construction measures covered by NRCS are funded under the program, but real-property rights (easement acquisition) and some administrative items are sponsor responsibilities.

Jason Dodds, a city staffer who will help coordinate funding discussions with sponsors, told council members that the planning phase is funded and the next steps are final design and, eventually, construction if funding is approved. "We still have about 8 months to get through this planning phase," Preet said, noting the record-of-decision and final plan EIS would be required before sponsors apply for construction funds.

Council members asked about ownership of the bluff where the detention structure would sit; Preet confirmed that the upstream site is on BLM land, which reduces private-property acquisition needs but creates a need for interagency coordination and easements for channel work in town.

The city will be notified when the draft plan EIS is released for public review and the project team plans to reach out directly to property owners with affected parcels. The council did not take formal action at this meeting; staff was directed to work with NRCS and the sponsors on public outreach and to track the public-comment schedule.

If adopted and constructed, the measures are designed to convey a 100-year flood through the improved channel with significantly reduced flood depths in town and materially lower risk at 500-year events, according to the consultant's summary modelling.