It's a gorgeous, sunny September Sunday afternoon when my friends and I carry our boats down the cement boat launch at Boom Island park in Minneapolis and slip them partway into the Mississippi. Our group includes three canoes, three adults and four kids ages 10 and younger.

Sticks and a couple of empty chip bags swirl in an eddy as we snap on our life jackets, secure our lunch bags and situate ourselves in the boats, preparing to paddle to Hidden Falls Park in St. Paul. It's one of the last times we'll be able to travel this route.

By June 2015, the Upper St. Anthony Lock will close to boat traffic, probably for good, in what some say is an effort to thwart the advance of aggressive Asian carp (a few insiders dispute this point, noting there are other ways the fish can advance into our waters). At the same time, closing the lock will eliminate one of the Twin Cities' finest urban adventures: the opportunity to travel through Minneapolis on a recreational watercraft, including a canoe.

The Upper and Lower St. Anthony Locks are the northernmost on the Mississippi, about 6 miles farther upstream than the official Lock and Dam No. 1, just beneath the Ford Bridge in south Minneapolis. The St. Anthony locks were constructed in the 1950s and early '60s to accommodate barge traffic, which never arrived in the anticipated volumes. However, the locks have always been open to recreational boat traffic for no fee.

My canoe and I have made countless trips along this special stretch of river, a favorite destination when I'm hosting friends from around the world. With the big lock about to close, I've decided to savor the remaining opportunities to paddle the urban Mississippi. I've scheduled more than one trip to see the fall colors and bid farewell to the locks.

We push our three canoes out of the launch and onto the river. We make a straight line toward the far right side of the waters — none of us wants to go over St. Anthony Falls, located a little downstream to our left. In front of us are the downtown skyscrapers.

As we reach the other side, downtown slips from view. We pass Nicollet Island, go under the railroad bridge and see a couple of houseboats moored to the shore. About the time the Grain Belt Brewery sign comes into sight, the tree-lined shore gives way to walking paths and glimpses of the old mills. While the risk of going over the falls is always on my mind, the current is not strong enough to pull us toward any danger.

We paddle to the lock's concrete entrance and pull a cord attached to a speaker. A loud, crackly voice tells us to wait. Turns out, another canoe is on its way up.

About 45 minutes later, the lock opens. We wave at the other boat as we pass it going the opposite way. If this were a weekday, we'd be dwarfed by commercial barges and other big boats, but we still feel small paddling into the lock. It's a vast space, 400 feet long and 56 feet wide. A canoes takes up just 17 feet of this space.

We paddle to the middle of the lock where the friendly lock attendant instructs us to hang onto a buoy along the south wall. The massive steel door slowly shuts behind us.

We're so busy chatting, we hardly notice our boats descending. I suddenly see a watermark on the lock wall that's about eye level, and then within seconds it's above our heads. It takes about 10 minutes to release the 10 million gallons of water filling the lock. I'd like to say there's some drama in the process, like we're spinning down a drain or we felt the tummy-tickle of a roller coaster. There's not. It's a gentle, but impressive, drop.

By the time the downstream door opens, we've descended about 50 feet. A crowd of people has gathered on the Stone Arch Bridge to see what the opening doors will reveal. As the lock swings open, they see that 1.1 million cubic feet of space holds but a modest posse of canoes.

Ten minutes later, we're able to enter the Lower St. Anthony lock, located about a half-mile farther downstream, without any waiting. While the lock size is the same, the drop is about half of our first descent at 25 feet, and there are no plans to close the Lower Lock to boat traffic. (However, there is no designated boat launch between the Upper and Lower locks, and I didn't see any logical place to slip a canoe into the water. I suppose we could paddle upstream, do the Lower Lock and turn around. But I don't think my paddling buddies and I will ever try that excursion — what's the point?)

As we exit, we notice the current picking up speed as the river makes a sharp turn under the Interstate 35W bridge toward the University of Minnesota and into the Mississippi River gorge. If not for the frequent punctuation of bridges, a paddler might not even realize she's slicing through Minnesota's largest city. Trees line the river bluffs, punctuated by walking paths and an occasional hiker ambling along the river's edge. The foliage is just beginning to change; the reds and golds glow as the sun sinks lower in the western sky. This stretch of the Mississippi is part of the National Park Service for good reason.

I'll be sad to see the end of this era of urban paddling, when I can no longer treat visitors to sightseeing tours via the river. But that won't keep me from savoring my memories of ogling downtown Minneapolis from the middle of the Mississippi and dropping through those impressive locks.

Lynn Keillor is a Minneapolis-based writer and editor.