Unwanted Guests: October/November 2009
Invasive species, ranging from mussels to weeds, are costing the country billions.
By Doug Farquhar and Scott Hendrick
On a sunny day in the early spring of 2004, friends of Michigan Senator Patricia Birkholz took their 20-foot speedboat for a cruise in Lake Michigan. They were two to three miles off the coast when their motor seized. Mechanics later found why the engine had failed—the entire motor intake was full of zebra and quagga mussels that have spread throughout the Great Lakes in the last 20 years.
The mussels are just two of some 50,000 invasive species that have found their way into the United States. They include foreign plants, animals and microorganisms that spread quickly and aggressively, competing with native plants and animals. Global trade exacerbates the problem, with species hitching rides on cargo destined for U.S. ports.
Exotic species alter the ecosystem by changing the food chain, reducing biodiversity and upsetting ecological life cycles. They can transmit foreign diseases or parasites, clog water intakes, push out helpful species, and cause brush fires to spread easily.
Invasive plants already have taken over more than 100 million acres, from open spaces in the suburbs to pristine mountain meadows in our national parks.
The federal government has invested millions to curb the spread of these unwanted species, but it’s losing the battle.
Some state lawmakers are frustrated by the ineffective federal effort. They want bolder action. All 50 states have passed legislation to combat invasive species, and 25 states have invasive species coordinating councils. In 2009, legislatures in 40 states considered more than 180 invasive species related bills, and 64 were passed. They addressed everything from wild boars to boll weevils.
“States have to take leadership on this issue because different invasive species are going to affect states differently,” says Minnesota Representative Rick Hansen. “We have different ecosystems, and some are more susceptible to pests than others.
“In Minnesota, we have a significant population of ash, so we have a real threat from the emerald ash borer as it moves west. States can work in partnership with the federal government, but states need to take leadership because threats are different.”
The cost of invasive species in the United States is estimated at more than $120 billion annually. One study estimates annual losses to crops at $13 billion, grazing areas for livestock at $1 billion, and forests at $2.1 billion.
Agriculture has been hit particularly hard. Approximately 73 percent of agricultural weeds are invasives. And crop losses from nonnative weeds are estimated to cost farmers $24 billion each year.
The federal government invests $100 million annually to control alien plant species in ponds, lakes and rivers. Florida alone spends $14.5 million each year on controlling hydrilla, a fresh water plant. Fire ants cost Texas an estimated $580 million a year in control and treatment, repair to damaged machinery, and medical costs. The economic impact to Montana from knapweed is about $42 million a year.
Invasive insecs cause $13.5 billion in damages annually, and the United States spends about $1.2 billion on pesticides to manage them. An estimated 4 million wild pigs also pose a serious problem. They damage crops and were linked to causing the salmonella outbreak from California spinach in 2006.
Much of Michigan’s industry and economy is tied to the health of the Great Lakes, which have been under attack by invasive species ever since the St. Lawrence Seaway opened the lakes to international shipping in 1959.
“Invasive species cost Michigan millions of dollars a year,” says Birkholz. “They are having a devastating effect on our industry and a devastating effect on our economy.”
Today there are approximately 185 different invasive species in the Great Lakes alone.
“The most disruptive are zebra and quagga mussels,” says Marc Smith, state policy director for the National Wildlife Federation. The zebra mussel traveled from the Mediterranean to the Great Lakes in 1988. Quagga mussels followed in 1993. Both entered through the ballast water of ships.
Twenty years later, these dime-sized organisms cost the region an estimated $100 million to $400 million a year to control, and are spreading across the country. Zebra mussels have been found as far away as Lake Mead, outside Las Vegas. They invade freshwater lakes and overwhelm native species by reducing food and oxygen. They attach to pipes, screens and manmade objects, clogging water filtration equipment, pollution control outlets and electric generating plants.
“Zebra mussels have been a huge problem for Michigan,” says Birkholz. “They are even a safety problem.”
Experts agree a key to battling invasive species is to prevent their spread.
“Prevention is more effective than responding to biological pests,” says Hansen, a former soil and water conservation supervisor.
“Once they get a foothold, you are not talking about eradication, you are talking about management,” he says. “You have to look at prevention strategies.”
In 2005, Michigan became the first of the Great Lakes states to regulate ballast water beyond national standards. Michigan’s law requires ocean-going vessels, known locally as salties, entering state ports either to keep the ballast water onboard, or treat it before dumping it into the lakes. The law also requires salties to obtain a state ballast water permit.
Michigan’s law recently survived a challenge in federal court, opening the door for other states to adopt similar prevention strategies that go beyond existing federal standards.
Birkholz, the bill’s sponsor, says inadequate regulation of ballast water by the federal government created a need for states to act.
Under the federal Clean Water Act, the U.S. Environmental Protection Agency is responsible for regulating ballast water discharges into American waterways, but the wildlife federation’s Smith says they aren’t getting the job done.
“The EPA has punted authority to regulate ballast waters for 30 years,” he says. “The EPA issued a [ballast water] permit that was very weak. It required ships to flush tanks out only at sea.”
Birkholz is blunt in her dissatisfaction with federal action. “I’ve become so frustrated. They don’t have the guts to get this done. I’m sick of all the food fighting within departments at the federal level and in the meantime we are losing our economic and recreational opportunities.”
Efforts to control the spread of mussels and other aquatic invasive species go beyond regulating ballast water. In California, officials are ramping up efforts to inspect boats and other watercraft at the borders. From early 2007 to August 2008, the California Department of Food and Agriculture examined more than 150,000 watercraft for invasive animals and plants, finding pests more than 200 times.
“Mussels are another example of the large number of invasive species threatening California each and every day,” says Food and Agriculture Secretary A.G. Kawamura. “Our border stations do important work protecting the environment and the food supply.”
Inspectors also look for noxious weeds that can hitch a ride on watercraft. Of particular concern in California is hydrilla, which can displace native vegetation, clog waterways, disrupt water control features and hydroelectric facilities, and reduce water flow in canals. In a single irrigation district along the state’s southern border, hydrilla had infested an estimated 600 miles of canals, drains and laterals by 1986. In response, the California Legislature prohibited its importation and called for its eradication.
Last year, state inspectors examined more than 22.1 million personal vehicles and 7.3 million commercial vehicles at the state’s borders, rejecting more than 43,000 lots of fruits, vegetables and plants in violation of state quarantine laws, according to the agriculture department. More than 2,500 confirmed exotic invasive species were intercepted, including hydrilla, quagga and zebra mussels.
War on Weeds
Invasive grasses such as cheatgrass, a Central Asian weed with short leaves and long hairs, are causing wildfires to spread in the West. These plants, which often grow drier and denser than native grasses and shrubs, provide the extra fuel that contribute to record-setting wildfires.
In 1999, northern Nevada experienced one of its worst fire seasons on record, losing more than 1.6 million acres of cheatgrass -infested rangeland. Massive fires in the area followed in 2006 and 2007. This happened in areas where large fires used to occur only every 40 to 100 years.
Other states are not immune. A cheatgrass- infested area in Utah burned three consecutive years, from 2004 to 2006. In fact, cheatgrass fed the largest blaze in Utah’s history and Idaho’s largest in 97 years, both in 2007.
“There are well over 100 million acres in the West infested with cheatgrass,” says George Beck, a science professor at Colorado State University. “It’s the fire hazard that’s really scary.”
Utah Senator Dennis Stowell sponsored successful legislation last year, dubbed the “war on cheatgrass” bill, that provided money to combat invasive species in the most infested areas of the state. “When it catches fire, there is nothing you can do,” he says. “It’s like gasoline.”
Compared with the costs associated with wildfires—loss of grazing pastures and agricultural production—combating invasive weeds makes sense, says Beck.
It cost $50 an acre to reseed burned rangeland in northern Nevada following the 1999 fires. And more than $40 million has been spent in the area in the last 10 years to reseed and rehabilitate the area.
“The problem is only going to worsen,” says Beck. “Our society can ill-afford to wait any longer to become in engaged in the battle against invasive weeds. They are stealing our money.”
Doug Farquhar and Scott Hendrick track environmental health and agriculture issues for NCSL.