Lake Powell and the Colorado River are believed to be free of the mussels, which can damage boats and hydroelectric intakes, and pose a major threat to Lake Powell if they are introduced.

Under the program's expansion:

- All visitors bringing boats into the Glen Canyon NRA are required to display a certificate through their vehicle windshields stating their boat is free of zebra or quagga mussels.

- Visitors bringing boats into the recreation area will continue to be asked a series of questions at entrance stations to determine whether or not their boats may be harboring zebra or quagga mussels.

- If a boat is determined to be a zebra mussel threat, a mandatory decontamination cleaning will be required. Visitors will be required to proceed directly to the decontamination stations.

- To save time, visitors arriving at Glen Canyon may self-certify that their boats are zebra and quagga mussel free and display their required dashboard certificate by downloading self-certification packets at www.nps.gov/glca.

Violations of the program's regulations are punishable by up to six months in jail and a $5,000 fine, the Glen Canyon NRA says.