Quick Take   San Pedro   River ramble   Drive: From Tucson, take Interstate 10 East and exit onto Arizona 90 near Benson. Follow Arizona 90 south to Arizona 82. Turn east onto Arizona 82 and drive 10 miles to the San Pedro River near the ghost town of Fairbank.   Walk: Those who want to trek on a trail will find a trailhead at the Fairbank townsite. Those who prefer a riverside ramble need merely follow the water.   When: Dawn to dusk   Cost: Free   Et cetera: Be aware that the watercourse is a travel route for some illegal entrants from Mexico.

ALONG THE SAN PEDRO RIVER - One sound spoils the perfect silence of a cool winter morning, but it is a sweet noise in this arid land. Flowing water. The faint melody of water on the move - a little whish here, a soft gurgle there - is one of the pleasures of a ramble along the San Pedro River, southeast of Tucson. You'll need no life preserver as you trek streamside for a mile, or miles on end. The San Pedro is not the muscular Mississippi or the thrashing Colorado. It's a subtle little river, with a depth usually measured in inches, not feet. This is a place for easygoing exercise and maybe a kind of riverine meditation. One of the finest stretches of the river - from the Mexican border north to the Arizona community of St. David - is set aside as the San Pedro Riparian National Conservation Area. Many visitors begin their explorations at the San Pedro House, a visitor center near the river on Arizona 90 about seven miles east of Sierra Vista. Another access point, sometimes affording a bit more solitude, is at the spot where Arizona 82 crosses the river near the ghost town of Fairbank. There, on a recent morning, an overnight freeze has trimmed parts of the riverbank with ice and transformed the surface of a small tributary into a glasslike sheet. Enormous streamside cottonwood trees, naked of leaves for the winter, stand out starkly against a deep blue sky. A red-tailed hawk soars high over the water. Jack Whetstone, a biologist with the U.S. Bureau of Land Management, says it's common to spot the graceful birds of prey along the watercourse during the winter months. "Down along the river at this time of year you might also see an Abert's towhee or Say's Phoebe," Whetstone says. "You could also see a white-tailed deer." He notes that vegetation along the San Pedro includes Fremont cottonwoods, Goodding willows and velvet mesquite trees. The conservation area has a network of trails, but many hikers choose to just follow the river, with all its bends, bows, twists and turns. Over there is a little sandbar that needs investigating. Will the thin ice on that 3-inch-deep tributary hold the weight of a 190-pound man? Answer: Nope. Farther downstream, an amber clump of dead grass invites one to sit down by the water and meditate. Or is that day-dream? A single white cloud drifts overhead. The river whispers by - always the same, and not the same at all. Quick Take San Pedro River ramble Drive: From Tucson, take Interstate 10 East and exit onto Arizona 90 near Benson. Follow Arizona 90 south to Arizona 82. Turn east onto Arizona 82 and drive 10 miles to the San Pedro River near the ghost town of Fairbank. Walk: Those who want to trek on a trail will find a trailhead at the Fairbank townsite. Those who prefer a riverside ramble need merely follow the water. When: Dawn to dusk Cost: Free Et cetera: Be aware that the watercourse is a travel route for some illegal entrants from Mexico.