SRP begins canal dry-up, relocating fish and repairing miles of water infrastructure

TEMPE – SRP workers stood knee-deep in the muddy bottom of the Tempe Canal on Friday morning, pulling a long metal fence through the shallow murky water as white amur fish thrashed in front of them. Workers began the first major phase of the annual canal repairs by herding and relocating the thousands of fish that help keep SRP’s canals clean.

“We’re in our first day of our annual Southside Dry Up,” said Justin Schonhoff, water maintenance manager for SRP. “That’s where we have 30 days to remove the fish, clean all the debris out of the canals, and repair any concrete lining that we see.”

Crews lowered the water in the canal to between 18 inches and two feet, allowing workers to slowly guide the fish into one area. Then workers with hand nets scooped the fish into the larger net, which was then lifted into a 1,200-gallon oxygenated water truck.

The fish, all white amur, are essential to SRP’s water-quality strategy.

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“We stock the white amur fish in the canals to eat the aquatic vegetation, so we don’t have to use chemicals or mechanically remove that vegetation,” said Brian Moorhead, an environmental scientist with SRP. He said avoiding contaminants is critical and added, “you don’t want to put a herbicide in the water.”

SRP stocks about 44,000 of the white amur fish across 131 miles of canal. They are triploid, meaning they have an extra set of chromosomes and cannot reproduce, and each fish must be certified before being shipped nearly 1,000 miles to Arizona. Fishing is allowed in the canal, but Moorhead said that the public must release the fish unharmed if caught.

The fish are quite expensive and are also protected under state regulations. The fish’s inability to reproduce is what prevents over population. It is also the main reason why these fish must be released if caught.

After the fish are moved upstream to sections of the canal still holding water, the next phase of the dry-up will begin. Excavators will roll into the empty canal to clear years of silt and the large amounts of debris that SRP crews encounter every cycle.

Workers regularly find shopping carts, furniture, tires, appliances, construction signs and even cars lodged in the canal. Some items are buried in silt, others sit partially submerged, waiting for crews to dig them out. Under ARS 13-1603, dumping that material into the canal is criminal littering, a charge that can rise to a Class 6 felony when the weight exceeds 300 pounds.

“Right now, as we’re moving fish, our biggest thing that we run into is debris,” Schonhoff said.

The growing debris as a problem does more than create work, it slows water flow and reduces the canal’s ability to move water efficiently, Moorehead said.

“The most basic reason for not dumping stuff in the canal is that is our drinking water,” he said.

Removing debris is costly, he added, and increases the frequency of dry-ups because items accumulate faster than the concrete ages.

Once the debris is removed, SRP crews begin cutting away damaged concrete lining. Years of sun exposure and water pressure cause cracks that grow into holes, allowing water to leak into the ground. That forces SRP to move less water through the system.

Schonhoff’s crew will peel the damaged areas back, fill them with dirt and spray new shotcrete to restore the structure, he said.

This year, SRP will use its newest tool: the Menzi Muck, a spider-like excavator designed to climb in and out of the canal without ramps. The machine’s wheels move independently, allowing it to crawl over steep edges and reposition quickly.

“It’s going to be very versatile because it can move very quickly up and down into different areas,” Schonhoff said. “We keep finding more and more useful things for it to do, which saves time and money.”

The Menzi Muck will be brought in once they get all the fish out and empty the rest of the water.

This dry-up affects multiple stretches of the Tempe and Western canals, and SRP has closed banks across those segments for safety. Heavy trucks and excavators will run along the edges throughout the month.

The work is scheduled to continue through Dec. 20, when SRP expects the portion of the canal to be repaired, cleared and ready to carry water again, allowing the white amur fish to return and get back to work.

“We have a lot of equipment, a lot of large trucks moving up and down the canal banks,”  said Schonhoff, adding that the closures are to keep both workers and the public safe.

The tight timeline means crews from several departments are pulled into the project, working long days in the drained canals before water returns. The annual effort is demanding but essential,  Schonhoff said.

“Keeping the canals in good working order is important to make sure we’re still able to deliver reliable water,” he said.

This article first appeared on Cronkite News and is republished here under a Creative Commons Attribution-NoDerivatives 4.0 International License.