PHOENIX — Maricopa County will begin a $98 million project to rehabilitate an aging dam in the desert west of Phoenix.
The U.S. Army Corps of Engineers in 1956 built the 18-mile McMicken Dam to protect Luke Air Force Base from flooding. The base flooded in the early 1950s when runoff from heavy rains flowed south through what is now Trilby Wash and inundated the base.
Since then, several cities and towns have developed in or along the floodplain near the earthen dam.
The Maricopa County Board of Supervisors last week approved a 10-year rehabilitation plan for the dam to ensure its safety. The design phase of the project is expected to be completed by 2014, according to the Maricopa County Flood Control District.
The dam begins in the desert north of Sun City West and stretches southwest through Surprise and into an unincorporated area north of Luke.
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The Arizona Republic reports that while there is no imminent danger to communities engulfed by the dam, the structure is getting old. There are safety issues that have developed over time because the dam was built on outdated standards, said Tim Phillips, the district’s chief engineer and general manager.
“Most of the dams are built for a 50-year life, which, in theory, means at the end of 50 years you’ve reached when they no longer serve their purpose,” Phillips said. “Our goal is . . . with some repairs and constructions on them, maybe they can last for another 50 years.”
Population in the areas in and along the floodplain have grown by 69 percent since 2000.
All that growth means there are roads, residents and developments in the area now that were not taken into account when the dam was built, said Maricopa County Supervisor Max Wilson.
The preventive nature of flood-control dams means that if there is a danger, it won’t become obvious until there is a flood — and then it is too late, according to Wilson.
The Corps of Engineers and the district had an agreement to share the cost for designing the reconstruction.
The Corps was to provide $2.3 million of the $4.9 million design cost. The Corps has paid $361,000 to date, but there’s no guarantee that Congress will approve more money toward the project.
However, the county Board of Supervisors last week decided to put the county’s agreement with the Corps on hold and move forward with the project.
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