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Pacific Northwest Region
Boise, Idaho
Media Contact:
Joe Spinazola
(208) 334-9856

Released On: March 17, 2003

Migrating Fish Have an Easier Passage Upstream
Thanks to the efforts of landowners, irrigators, and federal, state, and local agencies, salmon now have an easier upstream route on the lower Lemhi River, near Salmon Idaho.

Two existing irrigation diversions, sometimes called "push up dams," on the lower Lemhi River were recently replaced with permanent, fish friendly diversion structures.

Chairman of the Lemhi Soil and Water District, R.J. Smith, had praise for the project and its effects on fish passage. The only thing that happened here is that fish now have passage. The irrigators still have their water and we no longer have to go into the river each year for a push-up dam, he concluded.

Irrigation diversions are structures in the river that direct water into an irrigation ditch or pipeline. A push-up diversion dam is constructed of cobbles and gravel that have been pushed up from the stream bottom by a bulldozer to create a barrier across the river channel. Push-up dams require annual maintenance and can block fish migrating upstream to reach their spawning beds.

The two Lemhi diversions, known locally as L-3 and L-3A, were replaced with structures constructed of rock and boulders donated by the Idaho Highway Department and obtained from a local road construction project. The structures were specifically engineered to incorporate large, natural materials in order to be more stable and to last longer than the push-up dams they replaced.

A six-foot wide slot provides for fish passage over the new diversion structure during low stream flow periods. In addition, a headgate was installed at one of the diversions to enable the irrigator to control the amount of water being diverted.

According to Al Simpson with Reclamations Salmon office, the funding from Bonneville Power and the participation of local agency personnel, landowners, and irrigators made the project a success. The cooperation was great. Everyone worked together, and of course, we couldnt have done it without the funding from BPA, Simpson concluded.

The total $250,000 funding for the two projects which were sponsored by the Idaho Office of Species Conservation was a grant from the Bonneville Power Administration. The Lemhi Soil and Water Conservation District and Natural Resource Conservation Service administered the funding and the local construction contracts. The Bureau of Reclamation designed the new structures and provided an on-site construction inspector. The Idaho Department of Fish and Games anadromous fish screen shop obtained the necessary topographic survey data and monitored fish populations during construction.

Brian Hamilton, Reclamation civil engineer, noted that none of the government agencies involved ended up owning the new diversion structures. This was a voluntary project where agencies only provided financial or technical assistance to the irrigators. At the end of the project, irrigators still retained ownership, concluded Hamilton.

Landowner Don Olson, who also serves on the advisory board of the Upper Salmon Basin Model watershed project, was involved in the project, too. He provided access for the contractors and noted that he never had a bit of trouble with folks working on his property.

Improving salmon passage on the Lemhi River is just one of a number of items identified as necessary in a Biological Opinion issued by the National Marine Fisheries Service (now NOAA Fisheries) on the operation of the dams that make up the Federal Columbia River Power System. The opinion was issued to Bureau of Reclamation, Bonneville Power Administration, and the U.S. Army Corps of Engineers in December, 2000. It identified 199 measures intended to improve conditions for anadromous fish and lead toward recovery of salmon and steelhead populations. The Lemhi Sub-basin, assigned to Reclamation, is one of the critical sub-basins identified in the Biological Opinion. As a result, Reclamation has assigned both a fisheries biologist and a civil engineer to the recently-opened field office in Salmon.

These structures are new to us here and I am really looking forward to seeing how they will perform, said Dan French, an irrigator who receives water at L3A. Hopefully, we will have a moderate spring flow so that the rocks at the base will set up really well, he continued.

According to Simpson, Reclamation seeks to provide technical assistance to irrigators regarding fish screens and stream diversions which affect anadromous fish passage. We also must consult with state and federal regulatory agencies to ensure that new structures are designed to meet current criteria for fish passage and screening, he continued.

To find out more information about the services Reclamation can offer, contact Al Simpson or Brian Hamilton at (208) 756-1064 or visit Reclamation at 102 South Warpath in Salmon, Idaho.

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