For decades, the Texas Hill Country's Guadalupe River has clobbered the sizzling summer blues with a double whammy of contentment: cold water and cold beer. But this year, state water watchers warn, tubers accustomed to running the rapids in the time it takes to consume a six-pack had better pack a case — and be prepared to get out and walk.

With a dry spell on the river's upper reaches now in its fourth year, managers of Canyon Dam have cut downstream discharges to a relative trickle. The result, say river outfitters from Canyon Dam to Gruene, just upriver from New Braunfels, is that while there is water enough to float, the thrills and spills of the river's modest rapids are gone.

"It sounds a lot worse than it is," said Theresa Rourke, manager of River Sports Tubes, which puts in just below the dam. "The river is low and slow. … What took two hours to run last year now takes 3½. But the water temperature's still in the mid-60s."

Shane Wolf, owner of Rockin' R River Rides, which rents tubes for two stretches of the river above New Braunfels, agreed.

"We're blessed with deeper channels than other parts of the river," he said. The trip between Gruene and Loop 337 "still is a great three-hour ride. That's three hours in the tubes, not walking," he said.

Dry spell for watershed

Bill West, general manager of the Guadalupe-Blanco River Authority, said Canyon Dam is releasing only 55 cubic feet of water a second. About 200 cfs are needed for a rollicking river ride, he said.

The core of the problem is a dry spell in the upper river's watershed that began in September 2007. Mark Lenz, a hydrologist with the National Weather Service's San Antonio office, said 2008 and 2009 marked the region's driest period on record. Abundant rains in 2010 largely missed the river's upper watershed, he said.

"Above Canyon Reservoir — Kerr, Kendall, upper Comal counties — that part of the watershed got shortchanged," West said.

He noted that Guadalupe's stream flow at Spring Branch, upstream from the dam, has dwindled to six cfs. The riverbed between that point and the dam - an area where river water seeps into an underground water system - is dry, he said.

The U.S. Geologic Survey this week reported that the river's flow from its Kerr County headwaters to its terminus at the Gulf of Mexico is just 10 percent to 24 percent of normal.

Many tubers who typically visit the Guadalupe have turned to the Comal River, a crystalline stream that springs from a hillside in New Braunfels and joins the Guadalupe a few miles later.

Hopes for big July 4th

The result, said Wolf, whose outfitting company operates a Comal River branch, is that the river is "pretty congested."

"Part of that," he said, "is people hearing the Guadalupe is closing. The second thing is, a lot of local people know the Comal is a spring-fed river. … The river is smaller, and it fills up faster."

The Comal also is suffering reduced flow. Geological Survey statistics showed flow for Tuesday at 177 cfs — 107 cfs less than the median flow for that date.

New Braunfels-area river outfitters said they are hoping for a robust July 4 weekend, in part to compensate for a slow Memorial Day start.

"They have a lot of high school graduations now on the Memorial Day weekend," said Ronnie Dreibrodt, owner of a Canyon Lake-area outfitter. "For the last couple of years, that weekend's been going slow. … Business is not as good as when the water was faster.

"But I'm still making a living."

allan.turner@chron.com