Idaho considers another Teton dam

FREMONT COUNTY, ID. — The Idaho Department of Water Resources (IDWR) has allocated $400,000 of its $1.8 million budget to study the feasibility of building a new dam in the Teton River Canyon.

An earthen dam that once held back the river failed on June 5, 1976, killing 11 people, wiping out herds of livestock, and rewarding $300 million in damage claims to people in communities downstream. The news that another dam is being considered has conservation groups buzzing, as well as people who lived through the 1976 disaster. There is even a Facebook group — Do NOT Rebuild the Teton Dam.

The water budget will also fund a study that could lead to raising the Minidoka Dam another five feet so its reservoir can store more water.

Both dam projects are part of that water officials first dubbed the “Upper Snake River Management Plan.” Now they call the Henry’s Fork Basin Special Water Study.

The IDWR presented the plan to the Legislature in February this year, but back then, the Teton Dam was not in the plan. The dam was in a 2007 Idaho Department of Water Resources (IDWR) report that identified 73 potential water storage sites in the Upper Snake River Basin and listed the Minidoka Dam enlargement and the Teton Dam reconstruction as “potential large scale storage projects that warrant consideration.”

IDWR estimates a new Teton Dam would create more than 300,000 acre feet of storage and provide power and flood control benefits. The dam would cost an estimated $435 million to build. It would be concrete.

The Minidoka Dam upgrades are estimated to cost around $100 million and would increase the reservoir’s storage by 50,000 acre feet.

Conservation groups are just beginning to process the news about the proposed Teton Dam and are expressing concern about flooding the beautiful Teton Canyon, a wildlife and recreational paradise to many residents and visitors.

Congressman Leo J. Ryan, of California, called the Teton Dam’s break “one of the most colossal and dramatic failures in our national history.” According to the Bureau of Reclamation, the 270-foot-deep reservoir took almost eight months to fill but drained in less than six hours, impacting the canyon and all living organisms in the river and its tributaries and even in the Henry’s Fork of the Snake River.

The Bureau of Reclamation was blamed for the dam’s collapse. An independent council found that the location BOR chose for the structure set it up to fail.

The 2007 IDWR report notes that, when considering dam reconstruction, “overcoming negative perceptions may be a challenge.”

Henry’s Fork Special Study Announcement – April, 2010
The Bureau of Reclamation and the State of Idaho, in collaboration with a stakeholder working group, will conduct a special study on water resources in the Henry’s Fork River basin to develop alternatives to improve water supply conditions in the Eastern Snake Plain aquifer (ESPA) and Upper Snake River basin in accordance with the ESPA Comprehensive Aquifer Management Plan (CAMP).
The special study area is upstream of the Henry’s Fork River’s confluence with the Snake River and includes the North Fork of the Upper Snake River, Fall River, and Teton River watersheds. It is also situated above part of the ESPA.
The special study will identify opportunities for development of water supplies (i.e., above-ground storage, aquifer storage) and improvement of water management (i.e., conservation measures, optimization of resources) while sustaining environmental quality. Alternatives will be developed in accordance with the managed aquifer recharge program of the Idaho Water Resource Board and the goals of the ESPA CAMP, and in consideration of the environmental impacts to the entire Snake River basin. The objectives of the special study are to assist future planning efforts and to provide specialized information that can be used for future decision-making processes at the state and local levels.
Federal water development projects on the Snake River above Milner Dam near Burley, Idaho provide full or supplemental water supply to more than one million acres of irrigated land. Over 1.4 million acres are irrigated by privately developed irrigation systems from natural flows in the Snake River and its tributaries or groundwater from the ESPA.
The analysis of water supply and storage will involve identification and evaluation of watershed hydrology and potential onstream and offstream storage sites. The focus will be on the availability, characterization, and quantification of the natural hydrology of the basin, including:
• seasonal volume of runoff and stored water available;
• surface water/groundwater interactions;
• irrigated agricultural areas;
• instream and offstream water uses;
• irrigation water distribution facilities and their operation; and
• the current characteristics and quality of riparian habitat.
The special study is expected to take two years to complete.