LOWELL — A wall of white water lurched up ahead in the churning Concord River as we dug in with paddles to keep our blue inflatable raft aimed somewhere between a rapidly approaching stone wall to the left and the rocks and trees on the right.
“Full ahead!” shouted the guide.
The raft bucked. Branches scraped our helmets. Waves chilled our hands and feet despite wet suits and splash jackets. And we could not stop grinning.
This was opening day for white-water rafting through downtown Lowell, a little-known annual offering that is made possible by winter runoff swelling the Concord River and driving high water over several drops before the Concord reaches its confluence with the Merrimack River.
The 1.7-mile journey carries boaters, almost unnoticed by the city of 106,000, down three sections of rapids, past centuries-old canals and Lowell’s famous mills.
Run jointly by Zoar Outdoor, an adventure outfit based in Western Massachusetts, and the private, nonprofit Lowell Parks and Conservation Trust since 2000, the trips run twice daily on weekends starting in April and continuing through Memorial Day, conditions permitting.
“This is one of the only urban white-water experiences out there and it’s only like this a short time of the year,” said Adriana Isaza, the marketing manager and rafting guide for Zoar Outdoor. “The water eventually recedes back to almost creek-like conditions. Once the leaves start coming back on the trees, that drains off the water.”
The Lowell rafting trips cost $82 per person and no prior experience is required. However, because of the danger posed by the rapids, the trips are open only to ages 14 and older, according to Isaza. Zoar provides wet suits, jackets, neoprene boots, helmets, and a safety briefing.
The rules are straightforward. Keep both hands on the paddle. Sit on the side of the raft, not the supports in the middle — they will bounce you into the water. Tuck your feet into the sides. If you fall out, do not stand up in the river; there is nothing worse than getting a foot jammed into rocks or logs as tons of water wash over you. Instead, keep your feet up and pointed downstream — someone will get you.
The river here is clean enough to fish and swim in, according to Jane Calvin, executive director of the Lowell conservation trust, which puts proceeds from the trips toward completion of the Concord River Greenway. Trips start and end at the University of Massachusetts Inn & Conference Center, which donates rooms for the rafting guides, who travel the two hours from Charlemont each weekend.
The stretch of river that Zoar rafts is known as “Thoreau’s portage,” hinting not only at the Concord’s literary past but also its generally unnavigable nature this time of year. The rapids have names, too: Twisted Sister, Three Beauties, and Middlesex Dam.
Unlike white-water rafting trips offered by Zoar in Western Massachusetts, where they have to coordinate runs with water-release schedules at hydroelectric dams on the Deerfield River, the Lowell flow is all natural, fed by the melting snow and heavy rains of spring.
“The fear every year is that we will lose the first weekend to high water and the last weekend to low water,” said Brian Pytko, another Zoar manager and guide.
And indeed, this season’s first trip was canceled, due to dangerous conditions on the river during the first weekend of the month. The organizers wait until the rapids reach Class 3 or 4 on an international difficulty scale that tops out at Class 6.
On the maiden voyage April 11, three rafts carrying VIPs, reporters, Zoar guides, and trainees faced a roller coaster of essentially all Class 4 rapids, with water surging at 2,180 cubic feet per second past a midriver gauge near Centennial Island. The waves were so steep along one stretch near the launch that a raft of trainees flipped over, leaving the rookies swimming — and laughing — in their wet suits and flotation vests.
One of the reporters along for the day also took an unexpected dip in the chilly rapids, only to be pulled back aboard by Pytko as Isaza ordered the rest of us to keep paddling “full ahead!”
Lowell Mayor Rodney Elliott and Greater Merrimac Valley Convention and Visitors Bureau staff members wedged their feet in place and tried to time their paddling with the person ahead of them, but sometimes paddled air as the craft tossed and bent in the chaos of white water.
Along the way, Elliott urged Pytko and Isaza to talk up the rafting trips at a City Council meeting, and pointed out the last of the Lowell mill buildings still in need of renovation.
“This is right in the middle of the city,” Elliott said of the river. “It is a resource we need to continue to look at as an economic driver. It does bring in tourists and visitors to Lowell to participate in a great event. Clearly, we know the water is always going to run, and this is a chance to get people on the water.”
In the calm between rapids, Courtney O’Malley and Alura Mireault — Lowell natives who work for the regional tourism bureau — pointed out the places along the river where scenes were filmed for “The Fighter,” a biographical movie about boxer Mickey Ward. They also admitted to being surprised that there is white-water rafting in their city.
“You know the river is here but you don’t think about it,” O’Malley said.
As the rafts neared a bridge, Pytko jokingly yelled up to two women passing by, “Hello, can you tell us where we are?”
“Lowell,” they shouted back, seeming a bit confused at both the question and the sight of boaters passing below the bridge. “You are in Lowell, Massachusetts.”
“We made it!” Pytko yelled back to chuckles in our boat.
The raft tours also offer a rare chance to enter the locks that once helped move lumber barges through Lowell en route to the sea without first plunging down a 30-foot waterfall. The locks date to the 1700s, and were rebuilt in the 1850s and the 1980s.
Volunteers turn levers that open doors and wickets to allow the lock chambers to fill, raising the rafts high enough to pass through one set of doors into the next lock, a process that takes about 20 minutes. Once at the top of the second lock, boaters disembark right at the hotel where they initially loaded into vans to start the trip.