Snake River lock system helps U.S. wheat get to international markets

Story and photos by RYAN HALL | RURAL MONTANA EDITOR 

The four lower Snake River dams may now be most known for producing clean, affordable and reliable power, and for their fish-mitigation measures. But when they were built, establishing a navigable channel for shipping barges was the primary goal, and that function remains key today. 

“The main reason they were built was for navigation,” said Paul Ocker, chief of operations and maintenance for the Walla Walla District of the U.S. Army Corps of Engineers, which oversees the dams. He added that the dams serve the most inland sea port in the Pacific Northwest, the Port of Lewiston in Idaho, allowing ocean access.  

Without the system of dams and locks, the river would not be navigable for barges and ships according to shippers. 

Ocker said the dams maintain a 14-foot-deep navigation channel for the barges and ships that use the lower Snake River. A majority of the lockages performed at the dams are for barges, though recreational lockages are also common. In recent years, cruise ships have become popular on the Snake River as well. 

“We have a number of cruise lines that have discovered the Snake River,” Ocker said, noting an estimated 28,000 passengers cruise the river annually. 

A worker throws a rope while a three-tow barge enters the lock at Ice Harbor Lock and Dam. These barges were hauling wheat, a common commodity on the Snake River. Photo by Ryan Hall

A wheat waterway

Most of the lock traffic each year are barges, with up to four large barges being pushed up or down the river by a tugboat. 

Ocker said a majority of what is shipped on the river is wheat, with 10 percent of the wheat in the U.S. traveling on the Snake River on its way to the Pacific Rim.  

According to the U.S. Wheat Associates website, more than 55 percent of all U.S. wheat exports moved through the Columbia/Snake River system in marketing years 2019-2020 and 2020-2021. 

“The Columbia-Snake River System is a superhighway of sorts for moving wheat and other agricultural products from farm to market,” U.S. Wheat Associates Market Analyst Michael Anderson said, according to the website. “The ability to move such a large volume of grain efficiently makes the river system a very cost-effective and ‘green’ logistical option.” 

One barge can carry as much as 35 jumbo-hopper train grain cars, or 134 semi-trucks. A four-tow barge, the maximum size that will fit in a lock on the lower Snake River, can replace 140 train cars, or more than 538 semi-trucks. In addition, according to Anderson, one barge can move a ton of wheat 647 miles per gallon of fuel, while a semi-truck can only move a ton of wheat 145 miles per gallon. 

How a lock works

The locks along the Snake River are important because they allow boats and barges to safely navigate the approximately 400-foot change in water elevation from the first of the four dams to the last. Each lock is about 666-feet long, 86-feet wide and holds about 43 million gallons of water. 

A barge traveling downstream pulls into the lock, and then doors close behind it and water is spilled out of the lock until the water level matches the downstream level, at which point the doors open and the barge continues its journey. When traveling upstream, the process works in reverse, with water being let into the lock until the water level matches the level above the dam — approximately 100 feet. Once that occurs, the barge continues upstream. 

Though the time varies by lock style, it typically takes less than 20 minutes for the whole process. At Lower Granite Lock and Dam, which has two hinge-style doors, it takes about 11 minutes to fill the lock to go upstream, and a few minutes longer to drain it for a downstream journey.  

“We are one of the fastest ones because we were the last one built,” Lower Granite Lock and Dam lock operator Neil Carlson said. 

Ice Harbor Lock and Dam, with its guillotine-style 740-ton gate that is raised and lowered with a 40-horsepower motor, takes about 15 minutes to fill for an upstream journey. 

“We do the most recreational boats (of the four lower Snake River dams)” said Harold Wentworth, chief of operations for Ice Harbor Lock and Dam. 

The average for that lock is more than three boats a day annually, while Lower Granite Lock and Dam sees about 1.5 boats per day, on average, though both dams have higher boat traffic from spring through fall. 

In addition to wheat and other grains, forestry products, fertilizer and vehicle fuel are shipped via barges on the Snake and Columbia rivers.  

“We truly have a global impact,” Ocker said. 

Republished with permission from Rural Montana Magazine, the magazine of Montana’s Electric Cooperatives Association (MECA).

Read this article in the September edition of Rural Montana: Rural Montana Magazine | September 2024 (PDF)

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