(First published in January 2012 and since updated)

Like Jack Welch, I, too, have a thing for canyons large and small.

Around Flagstaff, I've spent considerable time in the depths of Walnut Canyon and its cousins, Sandys and Fay.

And in Sedona, I have a passing acquaintance with more than a dozen declivities that have "Canyon" attached to their name.

But I have to admit, I've avoided Picture Canyon ever since a summertime hike more than a decade ago, before the treated sewage discharge was upgraded.

There was something about all that brown foam clinging to the cattails that turned me off to ever hiking again downstream of the Wildcat Hill treatment plant.

The old cars and discarded mattresses didn't help.

But once the upgraded treatment process took out 99 percent of the bacteria and biosolids instead of 80 percent, Picture Canyon -- named for its wealth of Sinaguan petroglyphs -- began appearing on the radar of many conservation groups. Volunteers, including Jack Welch, have made repeated cleanup forays to the point where Picture Canyon is now a National Historic Site and part of the city's permanent open space inventory.

So on the last Saturday in January, having run out of excuses to stay away any longer, I made a return visit to Picture Canyon and was amazed at the transformation. Yes, it is still hemmed in by a wastewater treatment plant, a cinder mining operation and a natural gas pipeline plant.

But the trash is gone, the outlet channel from the plant is now a permanent wetland full of ducks, and the canyon in winter is a torrent of waterfalls and spray below towering walls still housing the petroglyphs -- if you know where to look.

Downstream of the canyon, the Rio de Flag flows swiftly through mixed oak and juniper woodlands, eventually crossing under Townsend-Winona Road.

Picture Canyon in winter has a lot more water than in late spring and early summer -- the city of Flagstaff uses the treated effluent to irrigate parks, ballfields and golf courses. On this Saturday, the roar of the first waterfall -- about a 20-foot drop -- drowned out the shouts of a fellow hiker on the other rim barely 50 feet away.

There is an informal trail from the trailhead behind the treatment plant that skirts the holding ponds and a broad wetlands. The canyon comes up in about a quarter-mile, and here I faced a choice: hike the south or north rims, each of which has a trail.

I chose the north and left the south to the other hiking party, figuring we would meet up downstream of the canyon, which gives out in about a quarter mile.

But the less vertical north rim has several informal trails that descend to the canyon floor. So, with a little scrambling, I was soon down alongside the torrent, which nearly stretched from canyon wall to wall -- a distance in places of no more than 10 yards. Some matted cattail reeds along the shore helped to keep my boots dry until I could launch myself onto the mid-stream boulders and finally across to the other side.

I had been looking for petroglyphs as I descended from the north rim, but I struck out. After I had crossed and was climbing to the south rim, I met up with a member of the other hiking group, and he described a wall with black mold that contained what he said looked like a deer.

There was still snow at the base of the cliffs as I scrambled around looking for the picture, which I found nearly head-high after a few minutes. Whether it is authentic is hard to say -- vandals wiped out most of the drawings soon after Harold Colton wrote about them in the early 1930s. I'll post a photo of one of them with this story and see what kind of feedback I get.

The south rim has an old ranch road that heads generally east for about a half-mile until it crosses a new section of the Arizona Trail, which descends to the Rio de Flag downstream of the canyon. There's a barbed-wire cattle fence on either side to protect the banks and the wetlands, which in spring and summer teem with waterfowl and other animals.

On this day, I saw no tracks in the snow, animal or human. Winter might not be the best time to see wildlife at Picture Canyon, but it is the right season to catch the stunning power of a winter-long "spring" flood and the transformative powers of humans, too.