Historic Release at Alamo Dam Mimics Natural Flood, Improves Health of Bill Williams River
Bill Williams River Corridor Steering Committee Leads Effort To Manage Dam and Restore Rare Riparian Habitat Along River
Phoenix, AZ—February 24, 2005—A collaborative effort by several organizations is helping to guide operation of Alamo Dam so that water releases from the dam will improve riparian habitat along the Bill Williams River near Parker. The controlled release of water from the dam that began last week in response to recent rains and flood runoff will more closely mimic natural, seasonal flow patterns that enable restoration of the river’s natural processes and riparian, or streamside, habitats.
The Alamo Dam release is being coordinated by the seven-member Bill Williams River Corridor Steering Committee, with additional guidance provided by the U.S. Geological Survey. The multi-organization steering committee includes the U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, Arizona Game and Fish Department, Arizona State Parks, U.S. Fish and Wildlife Service, U.S. Bureau of Land Management and The Nature Conservancy. The group is committed to science-based, collaborative natural resource management and was created in response to a 1999 federal study of the dam that authorized it to be managed for ecological as well as other purposes.
“The conservation implications of this project are huge,” said Larry Voyles, regional supervisor, region 4, for Arizona Game and Fish Department. “We know that dams are essential to meeting the water needs of Arizonans. This project not only will help to meet those needs, but also to restore one of the last, best remaining woodland habitats along the lower Colorado River system.”
The flood release started February 15 with discharges up to 3,000 cubic feet per second (cfs) in response to a recent flood inflow. Releases will continue for several weeks, with a maximum discharge of about 5,500 cfs this week. Toward the end of the release, outflow will be gradually reduced to enable young cottonwood and willow seedlings within the floodplain to better tap higher groundwater levels created by the controlled release.
These releases serve multiple purposes for which the dam was authorized—flood control, water conservation, recreation, and environmental enhancement. Historically, the maximum peak flood flow on the Bill Williams River was more than 200,000 cfs and happened in 1891.
This controlled flood release will help to restore native trees along the corridor, benefit native fish and wildlife habitat and provide an opportunity to collect scientific data to inform future management, according to Pat Graham, state director of The Nature Conservancy in Arizona.
“The Bill Williams River corridor has been invaded by non-native tamarisk trees that have pushed out much of the native growth,” Graham explained. “This flood event occurs at an opportune time, when native cottonwood trees are regenerating. Not only will the return to a natural, high river flow help establish new cottonwoods, but its timing and managed reduction of flow later should inhibit invasive species from taking hold.”
According to Joe Evelyn, hydrology and hydraulics branch chief for the Corps’ Los Angeles district, the Corps values the opportunity to join stakeholders in formulating solutions that are acceptable and can be implemented at all levels—locally, regionally and nationally.
“The Corps benefits from the conservation partnerships, biological expertise, community presence and scientifically based approach to resolving natural resource management issues that our partners offer,” he said. “In turn, the Corps provides a multi-disciplinary staff and experience with water resources projects—especially now that environmental protection and restoration have taken on increased importance for us.”
The historic release also is part of the nationwide Sustainable Rivers Project—a partnership between The Nature Conservancy and the U.S. Army Corps of Engineers to change management of dams operated by the Corps on nine river systems nationally, including the Bill Williams River in Arizona. The project’s focus is to restore essential river flow patterns as a means of improving river health. At Alamo Dam, the Conservancy and Corps also partner with members of the Bill Williams River Corridor Steering Committee to achieve common management goals.
More than 340 bird species, including two on the federal endangered species list, have been observed in the Bill Williams River National Wildlife Refuge, managed by the USFWS. Also, the river’s watershed area is home to nine native fish species, or one-fourth of the native fish diversity in Arizona, including two on the endangered list.
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