A group of property owners and Arnold Irrigation District patrons are suing their irrigation district and the Natural Resources Conservation Service in an attempt to block a planned piping of a 12-mile canal. Save Arnold Canal, made up of Arnold patrons, started organizing after a draft environmental assessment of the piping project was released in June 2021.
The lawsuit alleges the plan to pipe the canal would violate the National Environmental Policy Act, the Watershed Protection and Flood Prevention Act and the Administrative Procedures Act. They claim AID failed to thoroughly explore alternatives to piping. They also are concerned with the loss of the habitat that's formed around the canal, damage to property resulting in reduced property values and that water won't be able to seep back into the ground to water nearby trees and recharge aquifers.
Last year, Arnold patrons told the Source Weekly their preferred solution would be to line the canal with geotextile liner and shotcrete — commonly called canal lining. Unlined canals can lose up to 50% of water that seeps into the ground, whereas lined canals only lose about 10%. No water is lost in piped canals, but seepage waters trees near the canals and can recharge aquifers.
The director of modernization at Farmers Conservation Alliance, the agency that prepared the environmental assessment, said lining was ruled out because it cost nearly twice as much in the long run because piping requires little to no maintenance. He also said piping contributes a relatively small amount to water level declines in aquifers, but that it's paltry in comparison to withdrawals or the changing climate.
The environmental assessment says it will modernize 149 of the district's 646 patrons' lines, saving 32.5 cubic feet per second from seepage loss during irrigation season. The excess water will be transferred to North Unit Irrigation District, which holds the most junior water rights in the Deschutes Basin but has more commercial agricultural production than other irrigation districts in Central Oregon.
