Weed-eating fish clean canals

As one of Arizona's largest water suppliers, SRP delivers approximately 1 million acre feet (1 acre foot = 325,851 gallons of water) to metropolitan Phoenix each year through its 131-mile canal system. Aquatic weeds pose a constant challenge and, left unchecked, an overgrowth of weeds would impede water flow and displace precious space in the canal needed for water transport.

In the past, SRP controlled weed growth with costly and labor-intensive methods, such as scraping canal beds with heavy chains to uproot plants, scooping out vegetation with backhoes, or applying herbicides.

Determined to find a more progressive, environmentally sound solution, SRP launched an innovative experiment in the mid 1980s – one that involved the use of white amur fish to clear the canals of weeds.

The white amur, a type of carp native to China, was selected for its ability to control moss and weeds at a wider range of temperatures than most other fish.

Special Stocking Permits from the Arizona Game and Fish Department requires the white amur to be certified as sterile before the fish can be imported and fish grates were installed to keep the amur in the canal system. For this reason SRP replenishes the fish population by trucking in several thousand white amur per year from fish farms in Arkansas. Once in the canals, the fish become accustomed to significant temperature variations and abrupt water chemistry alterations resulting from source water changes and storm water runoff.

A seven pound white amur can eat nearly three-quarters of its weight in weeds every day.

Impressive results

About 1,800 fish, weighing one pound each, were released in portions of the SRP canal system in early 1989. The stocking program was expanded every few years until 2005, when the last 23 mile section was stocked with white amur fish.

This progressive expansion allowed the new sections to be monitored to ensure the fish were maintaining control of the weeds. Also, it helped with the logistics of construction and installation of the hundreds of fish grates and structure modifications necessary to keep the white amur in the canals.

Machine cleaning of weeds in the canals has become a rare occurrence since the fish were introduced. This translates to saving additional maintenance costs, reduces the amount of heavy equipment traffic on canal roads, and less turbidity impacts to Water Treatment Plants.

The White Amur Fish Program saves SRP hundreds of thousands of dollars in annual operating costs and promotes innovative and environmentally friendly water management practices.

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Maintenance, care and protection

Because of its significant weed-eating value, the white amur receives special treatment. Each winter when SRP drains portions of its canals for maintenance, the white amur are carefully herded and relocated to "wet" canal areas.

SRP works closely with Arizona Game and Fish to address the loss of white amur to fishermen. Theft of white amur from the canals can be reported to Arizona Game and Fish, Operation Game Thief, at 1-800-352-0700.

Without specific controls, the spread of non-native plants and animals into Arizona canals and streams poses a threat to our water system environment. As such, aquarium fish and plants should never be released into SRP canals.

Additional information

A representative from SRP's Groundwater Department can provide additional information about the White Amur Fish Program. To request details, please call SRP at (602) 236-5304 or (602)236-2416.

Or write:

SRP Groundwater Department
Mail Station 16ST52
P.O. Box 52025
Phoenix, Arizona 85072-2025

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