Real-estate developers - national, local, and Canadian - who are changing the face of Dallas with the construction of huge office and mixed-use complexes, are running into a citizenry that has awakened to an awareness that the progress on which the city has long prided itself has its price.
Huge new structures, jockeying for position in the sky, are not only wiping out historic buildings but are beginning to threaten the winter sunlight sought by downtown workers.
Especially concerned is Peter Stewart, a business and civic leader who spearheaded Thanksgiving Square, a nonprofit foundation that built the five-year-old downtown oasis of grassy slopes, trees, and rippling waters on 3 1 /2 acres of city-swapped land with the city's truck traffic underground.
At the lower tip three huge bells on concrete pylons peak intermittently amid the traffic noise. Then at noon, business executives, workers, oldsters, and visitors sun themselves or eat a bag lunch while sitting on the grass or on the retaining walls beside the bubbling water.
But now, says Mrs. Stewart, about 40 percent of the sun's rays beamed in during the winter months from October to March have been cut down to 8 percent and the nearly completed 50-story glass office tower across the street dwarfs the spiral-shaped white granite chapel in the square.
Cadillac-Fairview, one of several Canadian real-estate firms that are putting up huge office towers as well as hotel and retail complexes across downtown Dallas, is cooperating with administrators of Thanksgiving Square to try to keep its scheduled First City Center and planned Elm Block from casting more shadows on the downtown garden spot.
''Now computers, inexpensively and quickly, can plot the sun from hour to hour during the months we've concerned about and give us a dotted printout of the effect of hypothetical tower positionings,'' said Mr. Stewart.
''Why pollute the springs one plans to drink out of?'' he asks rhetorically, citing the benefits of such an environmental amenity as Thanksgiving Square in the midst of a skyscraper-crowded downtown.
Bill Morris, vice-president of Cadillac-Fairview's Dallas-Fort Worth urban developments, says plans for the firm's under-construction First City Center nearby took into consideration the structure's effect on the surrounding sunlight.
A block farther, CF's tentatively titled Elm Block will have a ''quality retail development, four levels, 200,000 square feet, plus a hotel and two 40- to 60-story office towers that should give downtown Dallas a real spark.''
Consulting engineers have been directed to the computer information concerning the position of the project's office towers as they relate to winter sun in downtown Dallas.
''In ancient times architects used the sun intelligently,'' said Mr. Stewart.
''For about $1,000, now computers can tell us how a high-rise tower position can take only 30 percent of our sunlight instead of 90 percent.''
Requiring a less-technical solution was the problem of historic building preservation vs. new economic advantages of demolition of the Woolf Bros. building on a key corner of CF's planned four-block-square hotel, office, and retail project.
Dallasites had shopped for decades at the six-story store on land owned by Woolford Realty Company of Kansas City. For weeks CF's officers, the Dallas City County, the city planning commission, landmark committee, preservation groups, and Mayor Jack Evans's ad hoc task force had grappled with the problem and came up with a solution.
The city granted CF a demolition permit to raze the Woolf building while at the same time designating it a historic landmark. This prompted a major local TV station to editorialize that in Dallas, ''real estate can be stranger than fiction.''
A newspaper editorial called for an end to the ad hoc procedures, which are confusing to preservationists and developers alike, and proposed establishing of a definite policy.
Tom Faragher, chairman of the Texas Commerce Bank, said that CF had made a ''good-faith effort,'' spending thousands of dollars going back to the drawing board with architects and engineers seeking the possible incorporation of the Woolf building.
''But they would have lost 40 percent of their retail use,'' he said.
When the CF project is complete, it will connect by sky bridges with Joske's and Neiman-Marcus, two of the last three remaining major downtown shopping stores in the city.
Saying it wanted to be a ''good neighbor,'' CF's Bill Morris noted its incorporation of historic churches, warehouses, and other treasured buildings in its Trinity Center in Denver as well as a huge mall in Washington, D.C. In Toronto, Eton Center, a restoration project, attracts a million shoppers and visitors a week.
''But the Woolf building's impossible floor alignments and structural problems would have made the Elm Block look like a Hollywood set,'' said Mr. Morris.
Preservation groups, dismayed at the same-day demolition of several beaux arts and art deco buildings, urged a longer time span between the granting of a permit and the demolition process.
''We're not lobbying for total demolition denial,'' says the Historic Preservation League's Tom Black.
''Our effort is to educate owners and developers to the potential of restoration.''
The Historic Preservation League spent $20,000 on a study to inventory all Dallas buildings that are worthy, in its opinion, of historic designation. The Dallas City Council accepted the study.
But more and more buildings have fallen in the wake of profitable property sales by owners, and the city's drive to revitalize downtown Dallas with more shops, restaurants, and amenities available after work hours.
Dallas preservationists, however, are still plotting their strategies, including tax incentives for the rehabilitation of older buildings.