It's lockout time for invasive carp — and a few humans.

The Upper St. Anthony Falls Lock on the Mississippi River in downtown Minneapolis will be shut down in a year in an effort to keep the havoc-wreaking fish from spreading northward to Lake Mille Lacs and other northern waterways.

U.S. Sen. Amy Klobuchar, U.S. Rep. Keith Ellison and others congregated Tuesday in front of the lock to highlight bipartisan efforts to pass a $12 billion water transportation infrastructure bill that includes the lock-closing provision. The bill is awaiting President Obama's signature.

The lock is not heavily used by recreational boaters, which helped in gathering support for closing it. Still, opponents of the closure — mostly river industry groups — have argued that it could hurt the region's economy, particularly in the realm of tourism, and might not really stop the invasive fish from moving north.

The aquatic invaders, bighead and silver carp, can weigh more than 100 pounds. They are capable of eating from 20 percent to 120 percent of their body weight each day, handily outcompeting native fish and disrupting ecosystems. Native to Asia, they were introduced into the United States about 30 years ago and spread rapidly.

When a barge or recreational boat enters the Upper St. Anthony Falls Lock to go upriver, the U.S. Army Corps of Engineers closes the lock's lower doors and water is pumped in, rising like the water in a filling bathtub.

Once the lock is filled, its upper doors are opened and the barge or recreational boater can continue up the river.

Klobuchar said closing the lock is just a first step in stopping that fishes' northward drive. More research is required to find ways to fight invasive species without affecting other fish, she said.

"We are the land of 10,000 lakes," she said. "We won't want to turn into the land of one million carp."

Access vs. protection

The move is disconcerting to Bob Schmitz, who has operated Above the Falls Sports, a kayak tour business, since 2009. He loves showing off the Mississippi River's grand beauty and accessibility to Twin Cities visitors and residents. But moves to counteract the carp is slowly limiting that effort.

Schmitz said he stopped taking tourists through the lock two years ago, when the National Park Service and the Minnesota Department of Natural Resources asked him to set an example for other recreational boaters and not use it. He obliged.

Now, in addition to the Upper St. Anthony Lock, Above the Falls Sports and other recreational companies have been asked not to use Lock and Dam No. 1, which is south of the upper lock, near Minnehaha Falls.

"They'd rather us not lock through, but after careful consideration, we decided to continue going through" that lock, Schmitz said. "It is such an absolutely great way to learn about where we are and where we have come from in Minneapolis."

Schmitz said people all over the world have a hard time believing they can have easy access to the Mississippi River and unencumbered passage between the Twin Cities, and closing the lock cuts off that unique experience.

State officials, however, say protecting other waterways is important. At Tuesday's news conference, Minnesota DNR Commissioner Tom Landwehr emphasized that the state also has to deal with the invasive carp in the Minnesota and St. Croix rivers.

Gary Botzek, of the STOP Invasive Carp Coalition, said closing the lock is essential to protecting the $4 billion boating and fishing industries bring to the state every year.

"Those are tremendous numbers," Botzek said. "We cannot forget the Minnesota River and St. Croix River; those are totally unprotected."