Costs
of invasive mussel infestation, if it happens, could top $100 million per
year in the Northwest, economists say
July 27, 2010 |
Dime-sized freshwater mussels pose a multimillion-dollar threat to dams,
irrigation systems, and native fish species if they establish colonies in
the Columbia River Basin,
a panel of economists finds in a
report for the Council. The best
deterrent is a combination of watercraft inspections, public information
about the potential threat, and continued scientific research to better
understand zebra and quagga mussels, according to the paper by the
Independent Economic Advisory Board (IEAB).
“The IEAB’s report helps us better understand the
potential economic impacts of an infestation and underscores the point
that rapid response and public education are critical,” Council chair
Bruce Measure said.
The costs could add up quickly.
For example, the IEAB estimates the costs of cleaning water intakes
and related equipment at hydropower dams could total $16 million per year
for the federal dams on the lower Snake and
Columbia
rivers plus $5 million per year for other dams.
Cleaning spillway gates, juvenile-fish bypass screens, and other
related equipment would be about $150 per square meter or $3 million to
$10 million per year at the federal dams. There
could be additional costs in cleaning fish-passage facilities of at least
$1 million annually. Replacing
infested filtration systems at the 20 fish hatcheries that take some
portion of their water from the river or its tributaries would cost $1
million each — probably $3 million per year as the systems are replaced as
necessary — plus another $1 million annually for monitoring and cleaning.
As well, the costs to clean recreation facilities including water
supplies, docks, and boats are estimated as high as $50 million per year
but the upper limit really is not known.
Zebra and quagga mussels have caused millions of
dollars in cleanup and repair costs in the Northeast, Midwest, and Southwest.
The mussels are transported between water bodies on trailered boats
and other watercraft and are capable of living out of water for a number
of days. If water quality conditions
are right, the mussels disperse and multiply rapidly and form solid,
sheets of hard, sharp-edged shells that can completely coat underwater
surfaces up to several inches thick.
Not only do the mussels pose a physical problem by clogging water intakes
and pipes, fouling dam intake gates and adhering to boats, pilings, and
most hard surfaces, the mussels can have dramatic effects on ecosystems.
Mussel colonies can substantially
reduce food sources for zooplankton, fish larvae, and native mussels,
completely altering the food web and changing water quality conditions.
Calcium concentrations in the water appear to be
important in determining whether the mussels can colonize and reproduce,
as they absorb the mineral to make shells.
In much of the Columbia River and
its tributaries, calcium levels probably are too low for zebra and quagga
mussels to thrive. One exception is
the upper Snake River drainage in southeastern Idaho. There,
calcium levels fluctuate seasonally and vary from place to place, but are
often ideal for zebra and quagga mussels.
An infestation there could spread downriver to waters where calcium
levels are lower but still seasonally high enough to support mussel
growth. Research is under way to
determine whether the mainstem of the Columbia River
has sufficient calcium for mussels, but that is where the greatest damage
could occur if the mussels infested the big mainstem dams.
While the
mussels have not infested the
Columbia
River Basin yet, it may be
just a matter of time.
Boat-inspection and public-information campaigns are underway in each of
the four Northwest states, and several infested boats have been stopped
and cleaned entering Idaho and Washington from infested lakes in the
Southwest. According to the report,
“prevention buys time that can be
used to prepare.” In
its report, the IEAB assesses, with the help of scientific experts, likely
scenarios for an infestation in the Northwest.
In the worst-case scenario envisioned by the IEAB — a mussel
infestation in the Snake River — potential costs flow downriver with the
water into the Columbia and total in the tens to hundreds of
millions of dollars annually.
But there likely are other costs of an infestation
that were not addressed in the report, according to the IEAB.
For example, potential costs likely would involve habitat
replacement, reduced recovery of protected species, the likelihood of
other species declining and being listed because of food web and habitat
impacts, increased costs of complying with endangered-species laws, and
damage to economically important game fish.
As well, there would be costs beyond the impacts to fish, wildlife,
habitat, and hydropower. These,
which also were not addressed in the IEAB report, include potential costs
to commercial navigation, private waterfront facilities, and the
probability that an infestation in the Columbia River
system would lead to infestations in other Northwest water bodies.
Quagga and zebra
mussels are native to the Black and Caspian Sea
drainages. They were introduced to
the Great Lakes region of the
United States in the 1980s by
ballast-water discharges from ocean-going ships.
Since then they have spread throughout the Northeast and
Midwest
and, since 2007, the Southwest. In
response, a consortium of 19 western states, federal agencies, tribes, and
other invasive-species stakeholders developed an action plan to prevent
the mussels from spreading, respond to new infestations, and manage
existing ones.
The Council is
interested in the potential biological and economic impacts of an
infestation because of the potential damage to hydropower dams, which
supply about half of the region’s electricity, and impacts to fish,
wildlife, and related ecosystems. In
a related review in 2008, the Council’s Independent Scientific Advisory
Board (ISAB) considered the state of knowledge of the impact of non-native
aquatic species on native salmonids in the
Columbia
River Basin.
The ISAB found that the potential
impacts and risks to native salmonids and other native fishes from
non-native species are substantial, with most subbasins in the
Columbia
River Basin already
dominated by non-native fish species. Because
of these impacts, the ISAB recommended that the Council and fish and
wildlife agencies elevate the issue of non-native species to a priority
equivalent to that of habitat loss and degradation, climate change, and
human population growth and development.
The Council is an agency of the states of
Idaho,
Montana,
Oregon, and
Washington
and is charged by the Northwest Power Act of 1980 with preparing a plan to
assure the region an adequate, efficient, economical, and reliable power
supply while also protecting, mitigating, and enhancing fish and wildlife
affected by hydropower dams in the
Columbia
River Basin.Contacts:
