THE INNOVATORS
Tackling Aquatic Weeds at the Twin Falls Canal Company
By Brian Olmstead
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streams or anywhere that farmer return flows could get to fish-bearing waters. Meeting the label requirements and holding times for the chemicals was also difficult, so we stopped using the products in most of our system. In 2007, Dr. Cody Gray, a researcher for UPI, came into our office and said he wanted to do some testing on our system with UPI’s new Endothall-based aquatic weed IRRIGATION LEADER
PHOTOS COURTESY OF TWIN FALLS CANAL COMPANY.
The Twin Falls Canal Company, located in southern Idaho, provides water from the Snake River to over 4,000 irrigators across 202,000 acres. Our system has a large number of dairy farms that primarily grow corn and alfalfa. Others irrigators raise potatoes, sugar beets, dry beans, garden beans, wheat, and barley. We first delivered water in 1905 via a gravity flow system out of the Snake River, and gravity remains the sole source of power for moving water on the system to this day. The water flows downhill from Milner Dam and into the irrigators’ farmland through our unlined earthen canals and laterals. We have two primary canals that are 65 and 50 miles long, in addition to 1,000 miles of smaller canals and laterals. While the Twin Falls system has proven to be durable and effective, we do face a number of persistent challenges. One such challenge is that our water supply on the Snake River has been under increasing strain in recent years due to growing municipal, industrial, and agricultural demand. There has been a moratorium on expanding agricultural acres over the past 20 years, because we have reached the limit of how much water demand the Snake River can support. Water supply is an issue all the time, which is why we try to use water conservation all the time as well. Aquatic weed management is another significant challenge. Unlined canals like ours create ideal conditions for weeds to grow. By midsummer, there is usually a large amount of algae and pondweed in the canal system. Historically, we used heavy anchor chains dragged behind tractors to remove weeds. We had five crews working all summer on chaining teams consisting of highly trained operators and some high school students or other workers cleaning screens and removing debris. In the larger canals, we also had six large trackhoes set up to remove moss during chaining operations. We would usually have to chain the entire canal system twice each summer, and we would chain many of the smaller ditches more often than that. It would take up to 20 of our operations and maintenance workers 2 weeks to chain drag the main canals every year, and smaller numbers of people the entire summer to drag all the laterals. In the 1960s, we began using chemical weed treatment products like Magnacide and Xylene, but we were limited in where and how we could apply them. We could not use those products near spillway gates that led into perennial
