State officials on the lookout for Asian carp have been monitoring the Mississippi River. But there are new fears that the invasive species may use another gateway to Minnesota. Anglers in northwestern Iowa have caught dozens of the carp in waters that connect through streams and lakes to southern Minnesota.

A risk analysis by U.S. and Canadian researchers finds the food supply and breeding areas in the Great Lakes would allow Asian carp to spread rapidly. The report says just ten breeding females and a few males would be enough of a foothold for the invasive fish to populate all five of the Great Lakes.

The Associated Press reports the U.S. Supreme Court on Monday refused to hear an appeal filed by Minnesota and other Great Lakes states. The states asked the court to order the closure of shipping locks in the Chicago area to prevent the invasive Asian carp from spreading farther north.

The Army Corps of Engineers wants authority to close the lock and dam at Minneapolis' St. Anthony Falls at a moment's notice if invasive carp are found nearby. Supporters of the idea include the Minnesota DNR and Sen. Amy Klobuchar, who say stopping the migration of Asian carp up the Mississippi is needed to protect northern Minnesota waters.

The Obama administration's point man in the fight against invasive Asian carp says his agency is focused on protecting the Great Lakes. But he doubts the plan Sen. Amy Klobuchar is pushing is a viable way to keep the fish out of the upper Mississippi River.

State and federal officials are pushing a bill in Congress that would close the lock and dam at St. Anthony Falls if the invasive fish is found nearby. They say if Asian carp get any farther up the Mississippi River, they would threaten Minnesota's $11 billion tourism industry.

Researchers are taking water samples from nearly 300 different spots in the Minnesota, Mississippi and St. Croix rivers to determine whether the invasive carp have spread this far upstream.