THERE THEY WERE. Bulldozers smack in the heart of Yosemite National Park, one of America's scenic treasures.

"Ohmigod," we thought, not entirely in jest, "is Interior Secretary Watt strip-mining Yosemite Valley?"

To the contrary, says the park superintendent, Robert O. Binnewies. Well-tanned and with the tall, lean build of an athlete, at 44 he's the very picture of a ranger, even in office civies.

What had startled my wife Sandy and me, he says, was not the destruction of nature but the removal of a 250-space parking lot in front of the park's visitor center and busy grocery store. In its place will be a pedestrian mall "landscaped with native trees, shrubs and wildflowers."

Flowers in place of cars? I was elated.

I grew up on the edge of the park in California's Sierra Nevada Mountains and have visited it regularly for almost 30 years. But I had looked sadly in recent years on the increasing congestion, particularly in Yosemite Valley -- a seven-mile long, mile-wide scenic wonder famed for its plentiful waterfalls crashing more than 1,000 feet from granite cliffs.

Now, it appears, officials are taking significant steps to control the crowds (about 2.6 million visitors annually) and the cars that have given the park a reputation as a wilderness Grand Central Station. (A five-cent deposit on beer and soft-drink cans and bottles has cut back on a major source of litter.)

The mall restoration is part of the Yosemite "general management plan" published a year ago after five years of study and consultation with the park-using public, including an extensive questionnaire and hearings held across the country.

The plan, supported by such wilderness preservationists as the influential Sierra Club, represents a compromise: Some environmentalists would like to see the valley returned almost completely to nature by stripping it of grocery stores, hamburger stands, cocktail lounges and service stations now tucked in among the towering pines. On the other hand, many park visitors (the elderly, the handicapped, the sedentary) have come to rely on these services, and it's not hard to find those who would like more.

What the plan chiefly proposes in the next decade is the eventual elimination of all private automobiles from Yosemite Valley and their replacement by a public transportation system; removal from the valley of staff housing, administrative offices and maintenance and storage buildings; and future construction limited to the "periphery of the park and beyond."

Implementation, says Supt. Binnewies, has begun in a number of areas:

This fall the Glacier Point area, with its panoramic view of the valley -- "It probably ranks second only to the South Rim of the Grand Canyon for the most spectacular view," says Binnewies -- will be rehabilitated. The concession stand will be relocated away from the viewing point, and the heavily paved-over walkway to the cliff's edge will be replaced with a more "esthetically appealing approach."

An architectural plan for administrative offices and staff housing to be relocated at El Portal, just outside the park entrance, is "in the final stages." The existing park headquarters, a rustic log structure, may eventually be converted to a cultural history museum.

A transportation department study of park traffic patterns is due out in December. From these statistics, an overall transportation plan will be developed -- though ridding the park entirely of private cars, the superintendent admits, will be difficult if not impossible.

In support of the management plan, the park concessionaire, Yosemite Park and Curry Co., will soon move its reservation operation and warehousing from the valley to Fresno, 86 miles away. Already, they have begun to tear down obsolete buildings.

"For the past 90 years," says Binnewies, "development has been on the increase -- more houses, more roads, more everything. But the time has come to level off, to hold the line. The emphasis now will be on the quality of services. That seems to make strong sense to the National Park Service and to the concessionaire. We have to do a proper job of protecting our resource."

Still, he warns, "Yosemite is a complicated place," something of an understatement for a four-seasons park that can sleep as many as 11,000 people overnight in accommodations ranging from the luxurious Ahwahnee Hotel to your own tent in a high-country campsite. "Nothing is going to happen overnight." Improvements "will be gradual."

One thing he would like, he says, "is to see more decisions to visit the park in the fall, winter and spring and fewer on the Fourth of July."

To Sandy and me, the clash between civilization and wilderness in Yosemite was illustrated by a scene we chanced on one morning:

Two teen-agers were headed down the road, each with a fishing pole slung over his shoulder and a tackle box in one hand. Not an unusual sight in the great out-of-doors. But these two guys were hell-bent for the river on big-wheeled, city-slicker roller skates.

And though the park's summertime population may reach that of a small city, wilderness dangers still lurk. As many as 25 to 30 people annually die in the park, says Binnewies, many from falls and drownings. Yosemite "not only is a beautiful resource, it is an unyielding one. It gives no ground."

Let me say here that I have been something of a Yosemite snob for the last decade. On several visits during this period, I avoided the valley's congestion to backpack the relatively uncrowded trails that snake for 700 miles through the 90 percent of the 1,189-square-mile park outside the valley that remains mostly wilderness.

What, me stay in the valley? Not on your life.

I'm also one of those nature lovers who hoped the master plan would call for the elimination of most structures and services in the valley, opening it only to hikers and walk-in campers like myself or tourists riding non-polluting trams.

Our visit to the valley this summer changed my mind. Even with mid-August crowds, the valley is a delightful (and inexpensive) vacation spot. And it remains, with such obvious exceptions as a campground filled with RVs, almost as scenic as it must have been a century ago. Trees hide a lot of the blemishes.

My wife is a reluctant camper who had seen Yosemite only on one brief winter afternoon. I wanted her to see more of the park, and she agreed provided she didn't have to cart in her own bed and shelter. Her first choice, and I can't blame her, was the Ahwahnee Hotel.

But the park is so popular in the summer, we found when we phoned for reservations that even as early as March most accommodations for August had been filled. What was available was one night at the Ahwahnee ($74.20 a couple) and four nights in a Curry Village tent cabin ($13.25 a couple per night), which we took. (Medium-priced Yosemite Lodge was booked solid.) Sandy got her comfort at the Ahwahnee (at least for one night), and I got to sleep (almost) under the stars in our tent.

There is no denying that city folk swarm the valley in summer. The village mall with its pizza parlor, beer stand, deli, ice cream shop and grocery store is like a busy suburban shopping center despite its woodsy decor. Still, the point to remember is that away from the mall the crowds thin rapidly. Hike a trail up from the valley and chances are you'll be by yourself much of the way.

One warm, dry afternoon -- Yosemite Valley's climate (afternoons in the 80s and 90s; nights in the 50s and 60s; 30 percent humidity) is unbeatable -- we found a rocky trail leading up out of the valley along Tenaya Creek. We followed it for a couple of miles, stopping to picnic along the splashing waters and to take a (very) quick dip in icy pools.

Though the trail led to a lovely hidden waterfall -- you can't see it tucked away in a crevice until you're almost under it -- we met no more than a dozen other people that afternoon. And this within an easy hour's walk of the mall.

Another morning we arose at dawn to take a Kodak-sponsored hike into a nearby meadow for a free two-hour photography lesson. The idea was to get a shot of the bright-orange sun in the first few seconds it peeks over Half Dome. Except for our fellow students and five early morning hang gliders soaring down from the cliff (and a number of deer and raccoons who showed up, too), we could have been alone in the park.

Because of the valley tram system, Yosemite is one national park you can get to and visit without a car. A "substantial" number of park visitors -- about 15 percent -- are foreigners, says Binnewies, a great many of whom arrive by regular park bus service from Fresno ($13 one way) or Merced ($10.50), a two-an-a-half- to three-hour trip. "They certainly find their way around and seem to have an excellent time."

The trams are free and operate between campgrounds, lodges, shops and scenic points at 10- to 15-minute intervals from 9 a.m. to 10 p.m. Their reliability -- and the reduction of parking spaces -- keeps people out of their cars. As a result, Binnewies believes, traffic flows more smoothly now than it did a decade ago. Eventually, the plan is to improve tram service to other areas of the large park.

Most people seem to like the trams. A popular night activity is to board one of the double-decker, opened-topped trams for a 45-minute round-trip through woods and meadows by moonlight. We loved it.

What sold me the most on the valley, however, is that for so large a number of families it offers a superb vacation value. In this age of $40 and $50 motel rooms, it's hard to beat $13 for a wood-floor tent cabin. That includes bed and bedding, overhead light, dresser, towels and soap and free hot-water showers in the public restroom 75 yards away. Flip up the canvas window flaps for four-way natural air conditioning in the chilly night.

It's even cheaper, of course, if you bring your own tent or camper and cook your own meals. (Drive-in campsites in the valley are $4 a night, and reservations can be made through Ticketron.)

We shared our Yosemite trip with a former Berkeley roommate of mine, his wife and their three teen-age children. Their five-person tent rented for $25 a night. All of us ate dinner in the camp cafeteria -- trout, fried chicken, lasagna, roast beef -- for about $5 each from salad to dessert and tea and coffee. Sandy rated the trout "excellent."

Of course, Curry Village is not the Ahwahnee, which boasts vast lobbies and candlelight dining. The tents are clustered between rocks and trees by the dozens, and thin canvas does nothing to dampen the sound of a squalling baby or a youngster's portable stereo. Not to mention the inconvenience of rush-hour shower lines and the necessity, sometimes, of trekking through the dimly lighted midnight woods to the restroom.

From the valley, the most popular hike (don't expect to get away from the crowds on this one) leads to the top of Vernal Falls -- a stiff mile-and-a-half climb straight up stairways in stone to a small, sparkling lake above. It's called the Mist Trail because blowing spray from the heavy spring flow can soak you.

At that altitude (the valley floor is at 4,000 feet), the going is slow. If you're out of shape, expect to gasp with each step. Our group, even the young ones, rested every few yards. But the falls -- with a different view at every stop -- draws you on. And behind, you get an increasingly more splendid view of the river tumbling down its rocky canyon into the valley.

We picnicked by the lake, where fearless blue jays and squirrels tried to beg a share of our meal. My friend Jack, his two sons and I were tempted by the warm sun to take a plunge into the bright blue water. That led to the only misadventure during our Yosemite vacation.

The lake is fed by the Merced River, which courses down a smooth granite face, forming a natural water slide. Ignoring warning signs about the dangers, we edged ourselves into the current, sliding on our rumps for a dozen yards or more until it dumped us with a splash into the cold lake. Great fun.

Back again we went for repeated slides, soon wearing holes in our swimsuits. Then we got overconfident. Instead of edging into the current on our rears, Jack and I stepped this time into the swift stream.

Whoomp, he hit the slippery stone.

Whoomp, I went crashing down behind him, gashing an elbow to the bone. Fortunately, I had packed along a back-country first-aid kit, and Sandy was able to bandage me up to stop the bleeding. But for days after, the pain reminded me to heed park signs.

Despite the accident, we set out again for two more miles along the river to the top of Nevada Falls, another steep (deeper gasps) but equally scenic climb. There we soaked our aching and dusty feet in the swirling water before starting back down the three-and-a-half-mile trail. If going up is hard on the lungs, going down gets you in the leg muscles.

After cascading over the two falls, the Merced River quiets down for a while, winding slowly the length of the valley. Crowds flock to sandy beaches to swim in clear pools, but in the meadows away from the campgrounds you can find a pool to yourself. Many youngsters (and sometimes a grown-up) float down summer's gentle rapids on an inner tube or inflated mattress. Jack and I and his kids used mattresses. Sandy read in the shade of a pine tree.

For me, though, the highlight of the trip was the day we spent in the Tuolumne Meadows high country, reached by the only road that crosses the park. At 9,000 feet, the meadows is a 55-mile drive (or bus ride) from the valley, though it is only 10 miles on a strenuous uphill hike. We chose to drive.

From the meadows, we set out on a five-hour, seven-mile round trip hike to picnic alongside Cathedral Lake, nestled in a granite basin at the foot of a mountain peak like a church spire. Here, the tiny blue and white and yellow wildflowers still bloomed, and the clear air had a surprising chill for an August afternoon. Brief rain showers along the way sent us scurrying under trees for shelter, but we dried off quickly.

We passed a number of backpackers and day hikers -- more than I had expected -- but you could hardly call the trail crowded. This is the kind of country I have always enjoyed on camping trips. The hike to the lake, mostly up, took us through pine woods and small meadows and across snow-fed streams (even this late in the season). At times, as we topped a rocky ridge, we could see the peaks of the Sierras stretching for miles.

For the Yosemite Valley vacationer who, like Sandy, doesn't want to tote bed and board on an extended hike, Tuolumne Meadows offers a variety of day-long high-country treks along mountain streams or to an alpine lake. But take a jacket. The air turns cold when the sun hides behind a cloud.

After our five-day visit, I came away from Yosemite with the strong conviction that the park I've loved and enjoyed over the years is making a comeback from the troubled times of its recent past.

Not that there aren't some losses.

Petty, and sometimes serious, crime remains a problem. "No doubt about that," says Binnewies, though "it's not as bad as the average urban area. We have developed a more professional level of law enforcement."

In the back country, park officials now recommend boiling drinking water to eliminate a diarrhea-causing organism. We used to plunge our faces into the stream for a satisfying sip with no ill effects.

Gone, too, are the days when a backpacker could head out on a trail of his or her choice and enjoy the park in solitude. Nowadays, there are just too many backpackers for that. Wilderness permits are required for overnight stays to prevent high-country crowding and damage to the park from overuse. About 120 are issued daily at no charge. Most hikers, says Binnewies, have come to accept the permit system as necessary. If too many people are hiking the trail you want, wait a day or pick a different trail.

On the bright side, a computer study of trail use has resulted in greater freedom for the backpacker, he says, than under an earlier permit system. In the past, the hiker had to detail in advance where he or she would stay each night. Now, once you've got a permit to enter the wilderness at a specific trailhead, you can go anywhere from there and stay as long as you want.

As for the park's 350 black bears, they remain a hungry, potentially dangerous nuisance, says Binnewies, nabbing the unwary high-country visitor's food supplies if they're not properly stored. This can mean hanging them in a tree 15 feet from the ground.

But progress is being made. This summer the park staff tested a new lightweight food container for backpackers, designed, says Binnewies, to be bear-proof; something they might knock around but not break into.

With this, as with the park, he says, "We have high expectations."