This article was published on: 03/18/24 3:49 PM
For more than a century, Central Oregonians have thrived — and at times withered — because of the web of irrigation canals that stretch deep into the High Desert.
The history of the canals mixes politics, water law, agriculture and the environment, with the occasional scandal thrown in for good measure. These rock-lined channels have brought fortune to some and bankruptcy to others. They have greened up arid desert landscapes while simultaneously taking precious water from ecosystems.
Canals are now being reexamined by the agricultural and environmental communities, for both their effectiveness in delivering water to farms and the changes they bring to the environment.
Historical significance of canals
The first irrigation ditches were carved in the Central Oregon High Desert in the early 1880s, two decades before Alexander Drake founded the city of Bend. The ditches brought water to a handful of homesteaders trying to eke out an existence in Central Oregon by growing hay near the Deschutes River. As the canals spread, more people arrived to try their hand at farming the rocky soil.
Kelly Cannon-Miller, executive director of the Deschutes Historical Museum, questions whether Deschutes County would even exist without the legislation that brought canals to the area, including the Desert Land Act of 1877 and the Carey Act of 1894.
“So much focus is placed on the history of the mills, but getting irrigation canals in place so homesteaders could establish farms was the No. 1 economic development goal,” said Cannon-Miller.
Around the turn of the 20th century, canal building became a more industrial effort. The first large-scale project was the construction of the Pilot Butte Canal, which started in 1904 and was completed in three years. Powell Butte, Redmond and Terrebonne were formed as new communities, thanks to the creation of the canals.
Today, there are more than 1,000 miles of canal in the region. Central Oregon Irrigation District alone has more than 400 canals under its management, including sections that are designated as historic.
But Cannon-Miller, and others, also acknowledge that building canals across the volcanic soils in the High Desert of Central Oregon came with hard lessons.
“It was something that in many ways failed because of the geology and climate of the area,” she said.
How do Central Oregon’s canals work?
The canals are primarily gravity-fed and divert water from the Deschutes River and smaller stretches of water, including Tumalo Creek, Whychus Creek and the Crooked River. The irrigation season for the Deschutes is April through October, but even in winter, water periodically flows to provide water for livestock.
From the Crooked River, the season starts in February while Whychus Creek doesn’t have a specific season.
Senior irrigation districts, those that have older water rights, are given priority when it comes to allocating water. When there are shortages, the junior rights holders have less water allotted to them.
What are the challenges of managing, using canals today
There’s a laundry list.
Unlike water that flows through pipes, water is lost to evaporation as it travels through the open canals. Concern is sometimes voiced about their safety — people or animals that fall into a canal can have difficulty getting out.
But the most common complaint about canals is their porous nature. Irrigation districts say around 40% of the water that goes into their canals is lost to seepage.
Bob Jensen, a retired U.S. Forest Service engineering geologist, said the canals are not like a sponge absorbing water. Instead, water leaks away through areas where cracks appear in the rock floor of the canal.
“While the canals leak due to fracturing of the rock during flow and cooling, the leakage is not uniform along the length of the canal,” said Jensen. “There can be sections where there are few fractures, so it can take days for the water to leak away.”
Jensen said the rough, irregular canal beds help pools form in some areas when the water is turned off. Water that does breach the canal bed can make its way deeper into the subsurface.
Some of the leakage feeds vegetation along the canal banks, creating artificial ecosystems of ponderosa, juniper and other High Desert vegetation. Some feeds shallow perched water tables. The remainder continues downward to the regional water table where over time, driven by gravity, it slowly moves northward under Jefferson County.
The future of Central Oregon’s canals?
Canals served an important role in the development of Central Oregon, opening up the area to agriculture and luring homesteaders from the across the country to establish Bend, Prineville and other communities. The canals also offered a tranquil water feature for generations of Central Oregonians. In some areas, the seepage created strips of green that provided habitat for wildlife.
But across the region, time is running out for open canals.
Irrigation districts are tapping into federal programs to fund the replacement of canals with pipes, which are considered safer and don’t lose water to seepage or evaporation. Piping also allows irrigation districts to develop hydroelectric power projects to generate electricity that can be sold.
Perhaps most critically, the eight irrigation districts in Central Oregon are now bound by environmental regulations spelled out in the Deschutes Basin Habitat Conservation Plan, which calls for them to increase the flow of water in the Deschutes River over the next 30 years. Canal-to-pipe-conversion projects help the districts meet this obligation.
PIPING IN PRGRESS
Piping projects are happening across nearly all irrigation districts in Central Oregon. While not an exhaustive list, the following are some of the highlights.
North Unit Irrigation District, one the largest in Central Oregon is piping 27.5 miles of open ditches in Jefferson County. Piping the open ditches is expected to conserve 6,089 acre-feet of water annually. An acre-foot of water is the amount that can cover 1 acre of ground in 1 foot of water.
Arnold Irrigation District’s 12-mile-long piping project is one of the biggest in progress. The project will save 32.5 cubic feet of water per second. That equates to 11,000 acre-feet of water, or 5.5% of Wickiup Reservoir.
Lone Pine, Central Oregon’s smallest irrigation district with just 22 patrons is installing 10.9 miles of pipe. The project will conserve 5.3 cubic feet of water per second, or an estimated 2,103 acre-feet of water annually, for $9.3 million.
Swalley Irrigation District has piped 16 miles of canal and completed six out of 10 phases for its main canal and will start work on phase seven later this year. When phase seven is complete, the district will have approximately 9 miles of open canal left to pipe.
On the horizon lies the region’s biggest piping project, Central Oregon Irrigation District’s construction of a 21-mile-long pipe from Bend to Redmond to replace the Pilot Butte Canal, conserving 156 cubic feet of water per second. The latest cost estimate for that project is $250 million.