Mary Sue Roach: Galloway dam project has concerns that need to be addressed


March 21, 2014 

The Weiser River Resource Council is a group of concerned citizens from three counties who believe there are several concerns regarding the ongoing study of the Galloway dam project that need to be expressed.

Political pressures are pushing planning for this high-head dam near the existing Galloway dam. Previous efforts failed for several reasons: not cost effective, the recreation values minimized because of summer draw downs, flood control benefits were too small, the lower Weiser River channel was unable to handle the needed salmon flushing flows, the ecological impacts to the Weiser River and the loss of wildlife habitat were too great. All good reasons not to invest $500 million on an unneeded dam! WRRC supports efforts to restore the Weiser River to a healthy condition and retain the increasingly rare values of a free flowing river.

The major operation function of the proposed reservoir is to replace the 427,000 acre-feet of stored water, currently provided from Upper Snake River reservoirs, as agreed to in an ESA settlement to help endangered/threatened salmon and steelhead migrate to and from the ocean. The "salmon flushing flows" would mean the reservoir would be filled in late winter and early spring and then immediately released in late spring and early summer. These large releases of water would leave the reservoir at or below half full for the remainder of the year. The Weiser River has more than 20 miles of eroding river banks and produces in excess of 60,000 tons of sediment annually. With this much sediment loading the reservoir, the water would be dirty most of the summer and the drawn down shore line would be covered in layers of sediment.

The flood control benefits would be limited to areas downstream of the proposed dam. Expanding existing reservoirs, such as C. Ben Ross or Lost Valley, would protect all Weiser River properties and citizens at a very much lower cost.

We have concerns about dam safety. Recent core drilling showed both the left and right abutment geology is different than earlier believed, interspersed with tuff, breccias and clay. Even though the U.S. Army Corps of Engineers called the dam site suitable for a dam, they conditioned it on using special construction methods including a grout curtain and moisture preserving excavation techniques.

A portion of the Weiser River Trail lies in the footprint of the reservoir. According to the National Rails to Trails Act, the portion of the corridor that is inundated by water would have to be reconstructed to railroad standards. No easy task in this steep countryside. The reservoir would flood 7,000 acres of grazing land and wildlife habitat. This would also mean a loss of tax revenue from flooded private property.

If the Galloway project is built to replace the 427KAF obligated for salmon flushing flows, then the Weiser River would be required to export this large amount of water every year for as long as the dam exists, thereby constraining future water management options.

The $500 million cost estimate presented to the Idaho Water Resources Board by the corps is only construction costs and does not include further studies, analyses and reports, and property acquisition or mitigation measures.

Mary Sue Roach, of Weiser, is the chair of the Weiser River Resource Council, which is a chapter of the Western Organization of Resource Councils, with 10,000 members from seven Western states.

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