BOISE - Regional energy planners for four Western states are asking Congress for help building a stronger line of defense against what some officials call an unfolding environmental disaster - an invasive mussel that is clogging Colorado River reservoirs like Lake Mead outside Las Vegas after ravaging the Great Lakes region.

The Northwest Power and Conservation Council guides power and environmental policy in Idaho, Montana, Oregon and Washington, all of which are frustrated because boats continue to leave Lake Mead in Nevada and Arizona contaminated with quagga mussels.

It's seeking $2 million in federal aid to add watercraft inspection and decontamination stations to intercept boats carrying these rapidly multiplying, thumb-sized mollusks that could wreak havoc on Columbia River hydroelectric dams, farmers' irrigation systems and lakes prized for recreation. The water district in Los Angeles already estimates up to $15 million in annual expenses tackling quagga infestations that have damaged its aqueduct and reservoir system extending from the Colorado River.

"A second line of defense is not as good perhaps as stopping them at Lake Mead, but it's something we absolutely need to do when we can't depend on interdiction efforts," Phil Rockefeller, Washington's appointee on the council, said Tuesday at a meeting in Boise.

In 2012, a $1 million appropriation pushed by U.S. Rep. Mike Simpson, R-Idaho, was directed to support "mandatory operational inspection and decontamination stations" at sites including Lake Mead.

But only about half the money has gone toward inspection and decontamination work, according to the council, prompting Rockefeller to complain that federal agencies including the U.S. Fish and Wildlife Service and National Park Service aren't sufficiently invested in fighting the scourge.

Researchers don't know exactly how the mussels arrived at Lake Mead, where their numbers have increased tenfold to 1.5 trillion since their 2007 discovery. Some speculate they hitchhiked aboard a boat from the Great Lakes region, where the mussels have been proliferating for more than 20 years after arriving in the ballast of ocean-going ships from Eastern Europe. Mussels have damaged ecological systems and done hundreds of millions in damage in the Great Lakes region.

Given the mussels' rapid proliferation on the Colorado River, Idaho state Rep. Eric Anderson said stopping contaminated boats before they go elsewhere is the best way to combat the mussels' spread.

This year alone, nearly 80 infested boats have been stopped on the borders of Idaho, Montana, Oregon and Washington, most coming from Lake Mead.

"The fire is Lake Mead," said Anderson, a Republican who has become Idaho's leading legislative champion of fighting mussels. "We can't allow any more boats to come out of Lake Mead that aren't decontaminated."

Earlier this year, Anderson left 500 Idaho license plates underwater at a Lake Mead marina. After they've been encrusted with the mussels, he'll distribute them to Idaho outlets that sell boat tags - as visual examples of the mussels' potential toll. Revenue from these tags funds Idaho's $850,000 annual effort to keep mussels out of Idaho, including border inspections that began in 2009.

Amy Ferriter, invasive species coordinator at the Idaho Department of Agriculture, fears Lake Mead managers aren't doing enough. There are still no mandatory inspections, and Ferriter said she observed idled decontamination stations on a recent visit.

She also complains National Park Service officials have largely balked at requests to ask departing boaters for their destinations, then share the information across state lines, to better monitor such traffic.

Communication is so poor, the Northwest power council is considering filing a Freedom of Information Act request to force Lake Mead officials to divulge boater details.

"Given the high percentage of fouled boats coming from Lake Mead, this seems like a high-risk pathway," Ferriter said Tuesday.

Park Service managers at Lake Mead contend they've done more than anybody to try to keep mussels from leaving, but cite privacy laws governing boaters' personal information they say prevent them from passing along details from boaters to states.

Randy Lavasseur, assistant chief ranger at the Lake Mead National Recreation Area, said the vastness of the 248-square-mile reservoir, where water behind the Hoover Dam is diverted through pipelines and aqueducts for use in California, Arizona and Nevada, presents a challenge to federal managers in making sure every boat that leaves is mollusk-free. More than 8 million people visit every year.

Other states also are casting a wary glance at Lake Mead.

At sparkling Lake Tahoe on the California-Nevada border, two infested boats were intercepted before the July 4 holiday.

Both came from Lake Mead, said Ted Thayer, who manages the Tahoe Regional Planning Agency's aquatic invasive species program. His group estimates damage from a mussel-infested Lake Tahoe would result in $22 million in annual costs to the water supply, recreation and property values.

"We're concerned they are still showing up here," Thayer said from his offices in Stateline, Nev. "One really infested boat would be enough to infest" Lake Tahoe.

So far, managers at Glen Canyon National Recreation Area on Lake Powell in Arizona and Utah believe a mandatory inspection program has helped keep their waters mussel-free. Boaters who fail to abide by inspection rules face a mandatory court appearance, six months in jail and a $5,000 fine.