A foreign invader has made its way to Colorado, marking the second time
it has been found west of the 100th meridian and raising concerns for
fish and water supplies in the southern part of the state.
Zebra mussels, which have clogged pipelines and devastated aquatic
habitat in the Great Lakes, had never been known to exist in Colorado
until they were found at Lake Pueblo State Park by researchers from the
Colorado Division of Wildlife and Colorado State Parks in November. DNA
testing performed earlier this month confirmed their presence.
Two adult mussels and one immature specimen were found on substrate
sampling gear, and the larva -- called veliger -- was found by
performing plankton tows. That indicates the zebra mussels have already
reproduced at least once.
"I expect the fact that zebra
mussels appeared on Jan. 14, 2008, will be cited in probably a thousand
plans to do with water in Colorado in the next 5-10 years," Rob
Billerbeck of Colorado State Parks told attendees of the Colorado Water
Congress' annual meeting in Denver last week. "I'll be shocked if it's
not in the governor's 'state of the state' speech within a couple of
years."
The state has been conducting field sampling
efforts for several years to detect the presence of invasive aquatic
species in Colorado's lakes and reservoirs. Aside from a reservoir in
California, before the recent discovery at Lake Pueblo, the mussels had
not been found farther west than the Arkansas River in central Nebraska.
Despite
a national effort to stop the spread of the mussels, they have been
successful in expanding their territory since being discovered in the
United States in 1988. Officials say they probably were transported to
Colorado by someone who boated in waters infested with mussels. Given
their ability to attach to hard surfaces and survive out of water,
adult mussels can easily spread by hitching rides on watercraft or
transported in bilges, ballast water, live wells, or any other
equipment that holds water.
The invasive species, native
to eastern Europe, are notorious for their ability to eat large amounts
of plankton, depriving native species of the food they need to survive.
The zebra mussels may cause ecological shifts in the lakes they invade,
with consequences to valued wildlife resources.
"They do
pull a lot of nutrients out of the water column with, therefore,
expected major impacts on fish populations. That has been the case in
the Great Lakes. That is what we would expect in waters in Colorado,"
Billerbeck said.
Because these invasive mussels attach to
hard surfaces like concrete and pipes, the colonies can also affect
canals, aqueducts, water intakes, dams, fish ladders, fish screens and
boat motors. They have been known to grow to densities of 700,000 a
square meter.
"Picture all of your structures to do with
endangered fish covered in a foot of mussels," Billerbeck said. He
predicted that fish ladders and fish screens in Colorado could be
hugely affected by the zebra mussels within five years.
Congressional
researchers estimate zebra mussels cost the power industry $3.1 billion
from 1993 to 1999, affecting industries, business and communities to
the tune of more than $5 billion.
Pueblo Reservoir
provides 52 billion gallons of water a year to several cities in
Colorado, including Colorado Springs. The city is currently planning to
transport even more water to its residents via the Southern Delivery
System, a $1 billion pipeline project to carry water 40 miles from the
reservoir to the springs.
"How are they going to affect
the water delivery systems in Pueblo Reservoir? Right now, we don't
know," said Peter Soeth, a spokesman for the Bureau of Reclamation.
One
key to answering that question will be finding out more about just how
bad the situation is in Lake Pueblo. A dive team is expected to go out
to the reservoir in the next two to three weeks to determine the extent
of the mussel infestation.
Officials with the statewide
aquatic nuisance species working group met with Harris Sherman,
executive director of the Department of Natural Resources, this week to
present their draft plan to address species such as zebra mussels.
Elizabeth Brown, co-chair of Colorado's aquatic nuisance species
steering committee, said the group hopes to have its plan finalized by
this summer, so that Colorado will be eligible for invasive species
funding from the federal government.
"The zebra mussel is
a great example of why this [plan] is necessary," Brown said. "The
goals of the plan are to prevent new species from entering into
Colorado and limit the spread of what we already have by controlling it
or containing it."
Bills and bills ...
To be truly effective, though,
Brown said the state needs an aquatic nuisance species program, which
would require enabling legislation, and more funding, something Sherman
said the state is working on.
"We have a budget request
into the state Legislature to create a number of programs so that we
can be more proactive in quickly stopping the introduction of species
into our waters and reservoirs," Sherman said in an interview during
the conference. Sherman and his staff said they are still drawing up
the estimates for the budget request.
For the moment, most
of the prevention efforts are focused on boater education. State Parks
and the Division of Wildlife are planning a concerted effort to notify
recreational users at Pueblo Reservoir and other state parks about the
potential effects of zebra mussels.
The Pueblo State Fish
Hatchery, located below Pueblo Dam, will undergo an assessment to
determine options to prevent the spread of adult mussels and veligers.
To date, no zebra mussels or larvae have been detected in the hatchery
unit.
The hatchery raises a variety of warm and cold water
species of fish, including walleye, crappie, smallmouth bass, rainbow
and brown trout. No fish are planned to be stocked from the Pueblo
Hatchery until April, and the water will be treated to eliminate zebra
mussels prior to the fish being stocked.
"A plan is in
place to treat the fish before they're loaded on any distribution
trucks and treat the water in those trucks, which should dramatically
reduce, if not completely eliminate, the risk of any kind of
transport," said Greg Gerlich, Colorado's chief of fisheries.
While
boater education is seen as crucial to preventing the spread of the
mussels, Gerlich acknowledged that there is not much that can be done
to stop an infestation. "Once [an infestation] occurs, then we may do
localized treatments, but we may never be able to completely eradicate
them from the system," he said.
Officials are also
concerned about the spread of other aquatic invasive species,
particularly the quagga mussel, which was discovered in Lake Mead last
year and has since spread to six other lakes.
"In the
Great Lakes, the zebra mussels have largely disappeared. They've been
replaced by quagga mussels, which are their evil cousin that grow at
higher growth rates, grow in deeper, colder waters, softer sediments --
all the things we have in Colorado," said State Parks's Billerbeck.
"This is not good news."
Gable is an independent energy and environmental writer in Woodland Park, Colo.
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