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White Tanks No. 3 FRS

White Tanks No. 3 Flood Retarding Structure

Rehabilitation Fact Sheet

Project Name: White Tanks No. 3 Flood Retarding Structure (FRS)

Sponsors:

  1. Flood Control District of Maricopa County
  2. Agua Fria–New River Natural Resource Conservation District
  3. Buckeye Valley Natural Resource Conservation District

Project Location: Western Maricopa County, Arizona

Authorization: Department of Agriculture Appropriation Act of 1954 (Public Law 156), and Public Law 106-472, Small Watershed Rehabilitation Amendments of 2000.

Project Summary:

The White Tanks No. 3 Flood Retarding Structure (FRS) was constructed by the Soil Conservation Service (now the Natural Resources Conservation Service - NRCS) in 1954. It is currently operated and maintained by the Flood Control District of Maricopa County. The 1.5-mile-long, 20-foot-high earthen structure provides flood protection to an estimated 6,000 downstream residents, 800 structures (including a state prison), agricultural land, and infrastructure. The downstream protected area which was primarily agricultural when the dam was built is now undergoing rapid urbanization.

The FRS has surpassed its original 50-year project lifetime and has developed safety deficiencies since the time of its construction, including subsidence and embankment cracking. To address these deficiencies, the Project Sponsors, with assistance from the NRCS, completed a Rehabilitation Plan and Environmental Assessment (Plan/EA) in 2004. The Plan/EA calls for rehabilitation of the FRS to provide for continued flood protection while meeting current safety and performance standards, including: dam modification to address embankment cracking and foundation issues; raising the dam crest; reinforcing the auxiliary (emergency) spillway; and installing an upstream diversion and flood channel to safely convey floodwaters into the FRS;

The Dam Rehabilitation Program administered by NRCS provides financial and technical assistance to help local Sponsors rehabilitate aging dams that were originally constructed with NRCS Watershed Program assistance. NRCS, Sponsors, and the Arizona Dam Safety Office are currently working on nine high priority dams needing rehabilitation. In order to receive federal funds for dam rehabilitation, local Sponsors must provide 35 percent of the total project costs.