I WOKE TO A glorious, clear blue-sky day. As the sun rose, sliding down the hills and canyon walls and turning their grays into browns, reds, greens and creams, the temperature followed. Within a few hours, it would shoot up from 45 to 80 degrees. In Mexico, across the river, mountains and a large butte caught the sunlight.

It was our first morning out on a week-long canoe trip. We had camped just up river from Horse Canyon, the first of a number of spectacularly high and steep-walled canyons we would paddle through for the next six days. Our group of nine had put in late in the afternoon the day before at La Linda, Mex., just below the Big Bend National Park in southwestern Texas. We were ready to paddle a 105-mile stretch through the Lower Canyon area of one of several sections of the Rio Grande designated "wild" or "scenic" by the Department of Interior.

Many people run the canyons of the river through the park; fewer try the wilder canyons that run from the park's eastern border through desert downstream for 130 miles to Langtry, Tex.

I'd given little advance thought to this trip, wanting only to be outdoors and "someplace else" for a week or so -- away from the pressures and routine of work. As a free-lance writer and photographer, I always keep pushing on to just one more project, one more contact. So the wildness and beauty of this desert area were especially stunning to someone who hadn't taken the time to work up any expectations. My only experience of the Rio Grande had been limited to seeing, much further southeast near the Gulf of Mexico, a rather boring river running between flat banks of irrigated farmland on the Texas side and a brown emptiness on the Mexican side -- hardly a scenic vacation area.

But this was altogether different.

I had signed up for this canoe trip with the American Rivers Conservation Council, or ARCC as it is affectionately called by its supporters. ARCC is the only national group lobbying exclusively for protection and conservation legislation for American rivers. Besides this work, the organization also runs a river trip program that includes a variety of canoeing, rafting and kayaking adventures. This was one of them.

We were on a part of the 191-mile stretch of the river which was added to the national system of wild and scenic rivers in November 1978. As a recent member of ARCC, I'd supported its work in theory, but had felt too busy to even look closely at the packet of information I'd gotten in the mail shortly after joining. Sure, I was for the environment and the protection of wilderness, but meanwhile I was buried in other activities.

This journey was to change that. The first night, a few miles down river from La Linda, we'd made camp on a soft, sandy river bluff and slept under a blanket of stars and small crescent moon. That first day we'd driven from San Antonio to the river, an eight-hour trip. Gil Miller, owner of Rough Run Outfitters, had met our group at the airport with a van. His assistant, Dave Hubbard, was ready for us at the river with the four canoes and supply raft that would take the nine of us (two guides and seven guests) down river.

During the whole of this trip, through Horse, Reagan, Big, Bullis and San Francisco Canyons, I was to be stunned with the beauty of this remote and unspoiled place and to feel again and again an almost religious awe in the face of such a vast expanse of wild desert.

Seven of us had booked the ARCC package and two had been on it previously. Our ages ranged from 24 to 71, with Dave Hubbard being the youngest and Kay Bachman, a retired dermatologist from Falls Church, the oldest. We were five men and four women. Most had some experience with white-water canoeing although, as it turned out, canoeing here was more a means to an end -- gaining access to this wilderness area rather than one of the main events.

We could paddle faster than Dave could row the supply raft, so frequently we'd simply sit and float, watching the canyon walls slip past. In many places the hills were set back from the river. But everywhere the characteristic desert vegetation was especially lush since it had rained recently. That proved to be a benefit for us: many more plants were in bloom and, in the faster-flowing water, the paddling was easier than it had been on two previous ARCC-sponsored trips.

I had never been in desert country before and found myself, contrary to my usual documentary, people-oriented bent, photographing everything -- flowers, rocks, animal tracks, scenery and yes, the other people -- running roll after roll of film through my cameras with abandon and excitement.

On the second day we passed the mouth of Maravillas Creek, actually a dry river bed. A frequent visitor to this area had written about this point: "At the mouth of Maravillas Creek you will pass the last place where anyone who wants to back out can leave the party for the next four days or more. It is only about a 20-mile walk from there to Black Gap Headquarters (a wildlife management station)." We were now committed to the river.

The sheer canyon walls don't allow people much access to the area and they also don't allow much animal life near the river. There's more in the Big Bend National Park. On the second day we did see four wild burros watching us from high on a hillside. And always we saw hawks. Most exciting of all was Gil Miller's discovery of mountain lion tracks at the entrance to an arroyo just above a large rapid where we were forced to walk the canoes through safer shallows. Two years before Gil had seen a cat drinking from the river near this spot.

Most days we could paddle in bathing suits and take brisk and cooling swims in the river. (I came back with a tan that had my friends asking if I'd been to the Bahamas.) Since I like to hike alone, I'd get up very early and hike an hour or two before breakfast. Such times were special. The mystery of the place -- its colors, quietness (except for the birds), the clarity of the light -- all made me feel removed into timelessness.

On the morning of the third day out, I climbed the hills behind our campsite into Mexico. The night had been cool and damp. As I climbed, more and more of the course of the river became visible from the ribbon of fog lying over the canyons that hid the river as it wound downstream mile after mile. By 8:30 the fog had burned off and the exact course of the river was lost into a maze of hills. After reaching a nice-sized peak, I sat and meditated a while. Descending, I came upon two very shy and scared javelinas, small wild pigs.

It was later on the third day that we saw other people for the first time -- two rafts carrying six Park Service people passed us while we ate lunch on rocks by the river. Otherwise, we saw few people except on the last day when we were a few miles above where we left the river. There a group of 10 Mexican men had strung a rope across the river and were in the process of crossing.

Gil Miller had organized food that was plain but excellent and was adapted to suit the desires of the two vegetarians in the party as well as everyone else. On a previous trip one fisherman had caught two 15-pound catfish. Catches up to 60 pounds have been recorded.

We paddled some or most of every day, except for the fourth day when we laid over on the Mexican side of the river at Burro Rapids. Here beautiful campsites lie near a warm springs that has been dammed up to form several large pools. After a hard day hiking or paddling, we'd sit in the pools at night looking straight up at the stars and moon that lit the canyon walls while small fish, indigenous only to these springs, nibbled at us.

On the layover day we climbed a high mountain south of our campsite. This was one of the great adventures of the trip, for we all sweated it out to the top, stopping once at a cave for a long lunch break. Even Kay made it, coming on slowly and steadily through prickly pear cactus and the sharp-pointed stalks of lechuguilla, an agave which will spear the unwary hiker straight through heavy pants. Purple sage, Indian paint brush, and most delicate and beautiful of all -- rock cactus--were in bloom. A wide variety of other desert plants stood ready to stick the unwary -- blind cactus, coryphants cactus which looks like a miniature sputnik and feels like a pincushion with all pins pointed out, and strawberry cactus full of soft rose and gray tones.

At the top we were rewarded with stunning views deep into Mexico and Texas. From here the hills looked soft and gray-green. As Dave commented, "I know some people like that, soft at a distance, but full of sharp points when you get up close." Before pushing off the next morning we hiked up the San Rocendo Canyon into Mexico to view an Indian pictograph of a man and burro.

As we moved down the river we became a closely-knit group. Different members helped with the cooking, cleaning up and mechanics of making and breaking camp. It's a great way to gradually get to know people. The more experienced paddlers handled the sterns of the canoes: Pete Hollenbeck, 39, an engineer with IBM; Pat Munoz, 39, the ARCC trip coordinator; Jim Welch, 36, an investments counselor; and Gil, 35, our outfitter. In the bows were Kay; Bonnie Piper, 32, on the staff of National Public Radio's "Morning Edition" show; Jay Butera, 24, a writer; and myself, 42.

Everyone except Kay, Jay, and myself had white-water experience. But we took no chances with the rapids and portaged the major ones, Burro and Upper and Lower Madison. Since it could take two days to get an injured person out of this area, we ran only those where the sole danger we risked was a canoe full of water. Rafts are more stable. Dave was able to breeze expertly through everything on the river, usually accompanied by our cheers.

All of us were in fair to excellent physical shape. Kay was a regular jogger, I swim and jog, and everyone else had been doing some exercise prior to the trip. Being in shape isn't necessary for the trip, though it certainly helps. But for the unexperienced, going with experienced guides is critical.

We left our campsites as undisturbed as possible, carrying out the garbage and scattering the fire ashes in the river. We saw few signs that others had been this way. For the first time the Thoreau quote I had once read on a Sierra Club poster came home to me: "In wildness is the preservation of the world." I'd always thought it almost hokey. But in the timeless canyons of the Rio Grande, the stresses and confusions of a jangled urban existence in our own uncertain times became, for a while, remote. And I could feel vastly grateful to those environmentalists and ranchers who had pushed to have this area protected so that I and others could experience the river and land undisturbed and wild.

For some, the specialness of the trip lay in a series of small daily events. As Pete said, "It was a lot of things -- just being in the wilderness; Kay climbing the mountain with the rest of us; the excitement of running some of the rapids; the closeness of the group, cooking and eating together."

Gil, our outfitter, and a songwriter, guitarist and entertainer, best summed up the experience for all of us in one stanza of his "Rio Grande Song": Majestic canyon walls With rapids great and small As we're paddlin' down The land of the Rio Grande. But you know I love it best For it's vast-spaced quietness. Nothing else exists When you're down on the land of the Rio Grande.

Tabor free-lances from Washington. If You Go . . . ---

Several airlines fly to San Antonio, including American, Continental, Delta, Eastern and Texas International. Cost of the canoe trip was $375, which included a $50 donation to ARCC. The outfitter supplied all food and gear, except for personal needs, and met us at and returned us to the San Antonio airport.

For more information on ARCC and its river trip program, contact Pat Munoz, The American Rivers Conservation Council, 323 Pennsylvania Ave. SE, Washington, D.C. 20003. Telephone: (202) 547-6900. Another trip scheduled for this winter is one to the Florida Everglades (Jan. 9-12).

Outfitters that run trips on both the Upper and Lower Canyons of the Rio Grande include:

Rough Run Outfitters, Seneca Rocks, W. Va. 26884. Telephone: (304) 567-2649.

Far Flung Adventures, Box 31, Terlingua, Tex. 79852. Telephone: (915) 371-2489.

Texas Canoe Trails, Star Route #3, Box 866B, New Braunsfels, Tex. 78130. Telephone: (512) 625-3375.