[Phoenix] MUSSEL IN CANALS & LAKES

[Phoenix Power Squadron]

Mussel in canal creates worries for CAP and lake
Shaun McKinnon
The Arizona Republic
Sept. 15, 2007 12:00 AM 
The quagga mussel invasion has reached the Valley.
An adult mussel turned up in the Central Arizona Project Canal in north
Scottsdale late last month, confirming fears that the tiny mollusks
would spread beyond the reservoirs of the Colorado River.
Just a single quagga was found in the canal, east of a bridge near Loop
101 and Frank Lloyd Wright Boulevard, but that specimen is likely "the
tip of the iceberg," said Larry Riley, a fisheries biologist for the
Arizona Game and Fish Department. "Where there is one, there are bound
to be others." advertisement
Quagga mussels pose no health risk to the drinking-water supply, but
they multiply quickly and can clog pipes, pumps and other equipment. In
lakes and reservoirs, the mollusks can rob other aquatic life of food
and oxygen, disrupting entire ecosystems.
There is no known way to safely eradicate a quagga infestation.
CAP officials say the mussels have not caused any maintenance problems
in the system and, until last month, no quagga had been detected beyond
the canal's starting point at Lake Havasu. CAP crews will use traps
along the canal to determine whether more mollusks have survived the
trip.
"We're trying to find out if they're spreading and, if so, how far," CAP
spokesman Bob Barrett said Friday. "This is one. It's an indication
they're there and surviving. We don't know yet how bad this is."
Authorities have struggled to contain the mollusk invasion to the
reservoirs on the lower Colorado, where the thumbnail-size shellfish
showed up early this year. The mussels, which had been confined to the
Great Lakes region for years, moved quickly from Lake Mead downstream
into Lake Mohave and Lake Havasu. 
Riley said biologists can only guess how the mussel made it to
Scottsdale, but quagga larvae can survive for weeks in moving water. It
is possible this one, and perhaps many others still undetected, floated
all the way down the CAP Canal from Lake Havasu, site of the
canal-intake structure.
The 336-mile CAP Canal delivers Colorado River water to Phoenix, Tucson
and Pinal County. 
Quagga larvae were discovered last month outside San Diego in a
reservoir that receives water from another canal, which links Havasu
with Southern California water users. The mollusks also attach
themselves to boats, which is how they probably moved from the Great
Lakes to Lake Mead.
Finding a quagga this far from the Colorado River was not unexpected,
Riley said. The only question was whether they would arrive in the canal
or on a boat that hadn't been properly cleaned.
"We have not detected them in other locations, but they seem to be
moving," Riley said. "When they find the right place and the right
habitat they can settle in, they begin to grow. As the numbers of adult
mussels increase, they will reproduce in that location and send babies
farther downstream."
Biologists don't know if the quagga could establish colonies in the CAP
Canal. While zebra mussels, a cousin of the quagga, have spread down
rivers in the Midwest, studies suggest the quagga don't do well in
moving water.
But they love lakes, and the CAP Canal is connected to Lake Pleasant.
Water from the canal sometimes flows into the popular reservoir and back
out into the canal.
"We haven't observed any adult mussels in Lake Pleasant yet, but once
they get there, it might be a fairly attractive place for them to set up
housekeeping," Riley said.
Quagga populations grow almost exponentially. A single adult mussel can
produce 30,000 to 40,000 fertilized eggs in one breeding cycle; one
female quagga can release up to 1 million eggs in a year.
Once established, the mussels filter phytoplankton and other food from
the water, disrupting the natural food chain. The mollusk waste
accumulates in the bottom of the lake and changes the water's chemistry.
Over time, the feeding process can strip parts of a lake of its oxygen
supply.
The quagga, an inedible shellfish, is native to Eastern Europe.
Scientists believe the first mussels arrived in the United States in the
late 1980s in the freshwater ballast of ships delivering freight through
the Great Lakes.
Just as the first quagga was found at Lake Mead as part of a search for
zebra mussels, the Scottsdale quagga was discovered during routine
monitoring for another aquatic pest, the caddisfly. The CAP regularly
checks the canal for caddisflies to limit large populations of the
insects.
CAP workers had earlier found quagga mussels at the canal's main intake
at Lake Havasu but had not confirmed any other specimens downstream in
the canal. 
Crews have inspected equipment at the Bouse Hills, Little Harquahala and
Hassayampa pumping stations west of the Valley, but no mussels were
found.
Jackrabbit Siphon, about 45 miles west of Phoenix, was drained for
repairs and inspected; no mollusks were found there, either.
Mussels infested the first few miles of the Colorado River Aqueduct, the
canal on the California side of Lake Havasu. The Metropolitan Water
District of Southern California, which operates the canal, drained it,
cleaned it and began disinfecting it with chlorine.
The CAP's Barrett said California officials have shared information with
Arizona, but so far, "it's not an infestation that's made us have to
stop operations and clean them up."
"They will not be allowed to accumulate to the point where they would
interrupt our deliveries," he added.
Authorities in Arizona, California, Nevada and Utah have stepped up
education campaigns in an attempt to better contain the spread of the
mollusks. Officials say boaters removing a watercraft from an infested
lake need to thoroughly clean the boat with hot water and soap or let it
dry completely before putting it in another lake.
"One of the things we don't want to happen is for folks to say, 'They're
already there, why worry'," biologist Riley said. "We don't want folks
to give up on the idea that maybe we can limit where these things go by
taking a few simple steps. We really have to rely on folks saying, 'I'm
going to do my part to try to protect our waters.' " 
     
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MORE ON THIS TOPIC
Containing the quagga
Quagga mussels probably hitched a ride to Arizona on a boat that had
been used somewhere in the Great Lakes region. That's why authorities
are pleading with boaters here to help prevent the further spread of the
tiny shellfish. Here are some tips:
• Before removing a boat from a reservoir known to be infested, clean
the hull, drain the water from the craft, dry the boat and any gear used
in the water, remove any visible plant and animal material, and inspect
any exposed surface.
• When you can, clean the boat with hot water and soap or with a
high-pressure hose at a commercial vehicle wash.
• Wait five days before putting the boat into another lake. The
waiting period will help kill the microscopic quagga larvae and any
other mussels that have attached themselves on the craft.
• Take advantage of inspections at marinas.
For more information, see www.100thmeridian.org.