Before dredging the canal, crews take fish for a drive

January 09, 2013

About 2 million people in the Valley have their water delivered by Salt River Project canals. For the first time in more than a decade, the entire canal system will be drained for cleaning and repairs. SRP plans to do it over the course of seven years. This month, crews are working on sections of canal north of the Salt River. As KJZZ’s Nick Blumberg reports, before workers can clean, they have to go fishing. 

The section of the Arizona Canal near 29th Avenue just north of Dunlap is 50 feet wide and 20 feet deep. It usually carries water to a City of Phoenix treatment facility, but right now it’s almost completely dry -- just a couple feet of water remain, along with knee-deep mud, silt, debris ... and a crew from SRP, including Justin Schonhoff, who's in charge of the fish moves.

In the late 1980s, SRP started filling the canals with white amur fish, also called grass carp. Today, about 18,000 of them help keep the waterways clear by eating algae, weeds, and other aquatic vegetation.

Arizona Game and Fish calls them "aquatic cows."

They’re sterile, and restocking can cost up to 20 bucks a pop. So before dredging a canal, SRP sends crews in to catch as many fish as they can and move them upstream to a section that hasn’t been dried out yet.

Schonhoff said crews mostly catch white amur, "but we also get other types of fish that come down out of the river system: we have bass, catfish, regular carp, turtles.”

SRP drains out parts of its canals regularly, but it hasn’t dried out all 130 or so miles for years. Schonhoff said the section we were standing along probably hadn't been dried out for 15 years.

"The last time it was dried was when it was actually cement lined," Schonhoff said, "and so, quite a bit of debris, a lot of mud.”

I pointed out a milk crate, a stroller, and some traffic cones, and asked Schonhoff what other kinds of things his crew finds.

Justin Schonhoff Justin Schonhoff is SRP's Biochemical Applications Supervisor. (Photo by Nick Blumberg)

“The main thing is the grocery carts and construction barricades. But we also find safes, we find furniture such as couches, beds, a foosball table, refrigerators. You name it, we’ve found it in here. A couple years ago we even found a Corvette.”

There weren’t any classic rides in sight, but from the canal bank it was easy to see the bright scales of fish darting through the muddy water. About a dozen people in waders dragged a length of horse fence through the canal.

“We corral the fish to one end of the canal, and then use hand nets and place them in the larger nets attached to cranes,” Schonhoff said.

Once workers have loaded the net full of fish, the crane lifts it out of the canal and positions it over a modified dump truck carrying a huge water tank. A worker standing atop the truck unties the knot that keeps the bottom of the net closed.

When the bottom of the net is open, it looks kind of like the top half of an hourglass; but instead of grains of sand, it’s a squirming mass of fish flopping their way through the opening and splashing into the water below.

After about 10 seconds, all the fish have made it into the tank, along with a couple Budweiser cans and water bottles. Now it’s time to tie the bottom of the net up, lower it back into the canal, and load it up again.

Schonhoff looks out at what his crew has found. “Big old catfish! See that big old catfish?"

The crew works its way down the canal a few dozen feet at a time, making a couple more passes to catch as many fish as possible. Next, maintenance crews will come in and remove the bigger pieces of trash by hand. 

“Once they get the bigger pieces of trash out, they’ll then go in with backhoes and tractors and start removing the silt,” Schonhoff said.

After the silt’s dry, they’ll take it to a landfill. Then they’ll move on to the next section of canal, every November and January for seven years.

For the rest of this week, Justin Schonhoff’s crew is still slogging through the canals in waders, herding the fish along with horse fence. I think the fence’s name may have rubbing off on one of them, whinnying his way down the bed of the canal.