Curt Deuser, liaison for the exotic plant management team at Lake Mead, said one agreement in the works will attack non-native weeds and shrubs in the Muddy River Valley.

Others could follow that target invasive tamarisk throughout Southern Nevada, fountain grass found near Laughlin and the Lake Mohave shoreline, and Russian knapweed in the Moapa Valley, Deuser said.

Congress on Tuesday finalized the measure as part of a broader public lands bill and sent it to President Bush. The White House has not signaled a problem with the bill, which suggests the president will sign it, said Matt Leffingwell a spokesman for Rep. Jon Porter, R-Nev.

"This legislation is a positive first step to provide the tools the park service needs to prevent excessive ecological and environmental damage to Nevada's lakes, rivers and open lands," said Porter, who sponsored it.

Deuser said the bill once signed into law will have broad impact. "There are other parks all across the country that have problems with invasive species," he said.

The bill was introduced in January 2007, after invasive quagga mussels were discovered in Lake Mead.

Roxanne Dey, spokeswoman for the park service at Lake Mead, said that with the new authority the agency will partner with California and Arizona officials to educate boaters to scour their hulls and take other steps to prevent further spread of the fingernail-sized mollusks.

The mussels can clog cooling water intakes and cause boat engines to overheat.