Erosion program saves farm land along American Falls Reservoir

Published online: Sep 02, 2013
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Erosion along the banks of American Falls Reservoir used to claim up to 3 feet per year of Dwight Horsch's farm land in Aberdeen, Idaho.

The sugarbeet farmer said those losses ended about six years ago, when a longstanding bank stabilization program led by the reservoir's canal companies brought in basalt rocks as rip-rap to protect his property.

"It is working very well," said Horsch, who believes the stabilization program has also kept the reservoir from filling with silt and improved the quality of irrigation water.

The congressional action that authorized the reconstruction of American Falls Dam in the mid-1970s directed the Bureau of Reclamation to purchase or protect shoreline from erosion. The bureau first compensated growers for farm land that had already fallen into the reservoir. In the early 1980s, the bureau started contracting bank stabilization work out to the same canal companies contributing fees for reservoir maintenance.

The program, which operates on a $590,000 annual budget, has protected 110,000 linear feet of shoreline to date, and the bureau hasn't had to purchase any lost farm land in more than two decades, said Keith Brooks, a bureau civil engineer who serves as project manager. Brooks said protecting land is the primary goal, and homes and farm fields are prioritized ahead of buffers of federal shore.

"You figure the reservoir has been there since 1926. Even 2 feet per year over a 50- to 70-year period, you're in there 100-150 feet," Brooks said.

He said the program has had a visible impact on water quality.

"If you would be on the reservoir shoreline when we had a full reservoir and waves, in the areas that haven't been protected yet you can see brown water out quite a ways, and in the rock areas it's clear water," Brooks said.

This year's work is focused on a long stretch upstream from the boat ramp at the dam, in an area that was previously protected but needs maintenance where rip-rap has washed away. Though several canal companies have provided labor throughout the years, three companies are currently involved in the project-Northside Canal Co., Falls Irrigation District and American Falls Reservoir District No. 2.

Rock is sourced from a quarry in American Falls.

Since the project started, Northside, based in Jerome, has taken the lead. Northside manager Alan Hansten sends some workers to American Falls each May to dynamite rock for a rip-rap supply. In July, he begins phasing staff into the project, assigning them to grade haul roads. Throughout August, he keeps 11 workers and 10 pieces of equipment, including trucks, at the reservoir, retaining a skeleton crew of workers in Jerome to maintain the canal system. He said workers like the assignment because they're paid higher wages for the inconvenience of being away from home.

Hansten likes having the Caterpillar D8 Crawler his company bought to move rock for the reservoir project available for emergencies on his canal system during the rest of the year.

Hansten said Northside earns a modest profit on the work but "the main idea behind it is being able to save all of the water users money."