LAKE BAIKAL, U.S.S.R. -- In April, the Central Committee of the Soviet Communist Party issued a decree for the protection of Siberia's Lake Baikal, a majestic body of crystal-clear water that is one of the natural wonders of the world.

The decree marked a new stage in the Soviet Union's awakening ecological movement. Its comprehensive plan of safeguards won praise from the band of dedicated environmentalists -- mostly literary figures -- who for 30 years have fought against encroachments on Baikal's wild and wooded shores.

Then, after a close reading of the decree's fine print, the cheering stopped. Now, once again, dissatisfied conservationists are up in arms, girded for another round against Minlesbumprom, a tongue-twisting Russian abbreviation that stands for the Ministry of Timber, Pulp and Paper, and Wood Processing Industry, which Siberian writer Valentin Rasputin calls "Baikal's master."

The drama here in eastern Siberia is typical of the dilemma faced by environmentalists everywhere in the Soviet Union. Despite new general conditions of "openness" and "democratization" ordered by Moscow, the struggle between environ-GORBACHEV'S IMPACT IN THE PROVINCES Third of a series mental interests and economic needs remains uneven. Public debate is tolerated up to a point, but in the end Moscow's ministries and the State Planning Committee make the plans, control the information and have the final word.

Still, the battle for the environment is now publicly engaged, unlike the days of the Soviet Union's extensive development, when planners in Moscow cavalierly ordered the damming of rivers and the tearing up of acres of Siberian forests in a race for raw materials.

The nuclear accident at Chernobyl last year heightened public awareness, and the Moscow press has taken a lead in the debates, exposing ever more cases of sacrificing the environment to the relentless demands of the five-year economic plan.

Here on Lake Baikal the issue is, as it has been since the early 1960s, the Baikalsk pulp factory on Baikal's shore. The factory produces 200,000 tons of cellulose fibers a year. Although a waste treatment system was installed in 1969, the factory still discharges effluent into the lake that has created a polluted zone measuring 23 square miles, according to conservationist scientists. From the air, the factory emits yellowish smoke that has enveloped 770 square miles of Siberian forest, according to Rasputin. More than 86,000 acres of fir trees around Baikal are drying up because of the pollution, according to official estimates.

When the Central Committee decree was announced, it was assumed that the factory would move its operations away from Baikal by 1991 and convert the premises to a furniture-making operation. It turns out that the pulp-making combine will stay until 1993. In the meantime, the polluting effluent will be carried away from Baikal by a 44-mile pipeline and dumped into the Irkut River.

Now the pipeline has become the issue, not only because of the pollution threat that it holds for the Irkut River, but also because, in the eyes of veteran Baikal defenders, the whole project smacks of an elaborate, expensive ruse to keep the pulp plant operating indefinitely on Baikal.

"What kind of a boss would throw away tens of millions of rubles on a temporary measure," asked Rasputin in a published interview. "In my view it is clear that this temporary measure is being done in order to be left behind as a permanent one."

The offending pipeline, estimated to cost 100 million rubles ($155 million at the official exchange rate), is also symbolic of a larger issue. At a time when public debate is being invited on a wide range of subjects, it struck some here as galling that the decision to build the pipeline was sprung on an unsuspecting public, apparently even against the advice of consulting scientists.

Speaking at a meeting in Irkutsk, Yuri Izrael, chairman of the State Committee for Hydrometeorology and Control of Natural Resources, said an ecological review of the pipeline should be conducted since it could have a harmful effect on forests and could damage the ecological system of the Irkut River. But when and how any such review will be conducted is still unknown.

It is this closed-door policy that suggests to the environmentalists that despite glasnost, or "openness," and the new attention paid to ecology, the five-year plan remains supreme.

At this point, the two camps are irrevocably split. Officials of the Baikalsk factory, beset by criticism, are refusing any interviews to foreign or Soviet journalists. Among the enviromentalists, there is a deep, abiding mistrust in everything coming out of Minlesbumprom.

"The ministry has lied to us before. There were other decrees before, and each time they went around them," said Rostivslav Phillipov, a Siberian writer who has been active in the struggle. "You can be lied to once; the second time, you will do some checking." A Unique Creation of Nature

Lake Baikal is one of the Soviet Union's great resources, a unique creation of nature: It holds 80 percent of the country's fresh water supply and 20 percent of the world's. It covers 8,850 square miles, and its crescent-shaped length stretches about 450 miles, as far as the distance between Moscow and Leningrad. But its most fascinating characteristics are its depth -- in places, more than a mile -- and its purity: They say here that one can see a stone lying more than 130 feet below the surface.

At its warmest, the lake's water reaches 61 degrees Fahrenheit, but the optimum temperature for its unique plant and fish life is between 35 and 39 degrees. Of its 2,500 species, 75 percent are unknown elsewhere in the the world.

A critical creature for Baikal's survival is a species of microplankton called the Baikal epischura, which filters the lake's water and is largely responsible for its cleanliness. According to one estimate, 7 percent of Baikal's pure water has been affected by damage to epischura's habitat.

Another creature unique to the lake is the Baikal nerpa, a fresh-water seal whose population of about 60,000 is now controlled by licensed hunting.

The fight to protect Baikal began before the April decree. But the history gives proof to an old Russian saying, which Phillipov is fond of quoting: "The severity of a Russian edict is undermined by the failure to implement it."

Indeed, several decrees have been issued in Baikal's name -- one in 1971 and another in 1977. A measure of their ineffectiveness was an order that came out of the Central Committee this spring, removing the deputy minister of Minlesbumprom, retiring the vice chairman of the State Forestry Commission and severely reprimanding half a dozen other officials for failing to carry out these decrees.

According to Izrael of the State Committee for Hydrometeorology and Control of Natural Resources, 697 violations of ecological standards on Lake Baikal have been reported. In 1986 to 1987, 18 cases were referred to prosecutors. The beleaguered Baikalsk pulp and paper combine is only one of the culprits. Another major offender is the Seleninsk pulp and cardboard combine, on the Selenga River, which is just starting to build a water recycling system that it was ordered to complete in 1977.

Officials at Minlesbumprom have often complained that they cannot keep up with the constantly changing environmental regulations. Minlesbumprom Minister Mikhail Busygin told Rasputin in a February 1986 interview in the government newspaper Izvestia that the Baikalsk factory has had to adjust to permissible effluent levels six times in 24 years.

"Six times. That is bound to make an impression on anyone. It impressed me, too," said Rasputin in a speech to the Writers Union congress the following June. "Not until recently, with enormous difficulty, did I manage to get a look at the figures for maximum permissible concentrations. And it turned out the standards had not been toughened at all but, to the contrary, had been relaxed . . . which is the only reason the number of violations had declined."

It was not the only time official figures were disputed by scientists backing the environmentalists. Each side has a scientific research institute to back its findings, and each side quotes different figures on the impact of pollution on the lake. The environmentalists' spokesman has been Grigori Galazia, director of the Limnological Institute located on the shores of the lake, where the Angara River meets Baikal.

The fight has left raw wounds. In the 1960s, when it was said that the cellulose fibers produced at the Baikalsk plant were needed for the Air Force, Baikal's defenders were accused of being traitors and CIA agents.

Now the warfare is more polite, but apparently just as intense. In June, the Communist Party newspaper Pravda, in a stinging article on the debate over the pipeline, noted plans to change the leadership of the Limnological Institute and commented, "If by that they mean to imply a change in directors, it is difficult to view it as anything other than revenge against a scientist for his struggle against bureaucratic interests." Two weeks later, Galazia was retired from the institute.

Rasputin even questioned the patriotism of Minlesbumprom Minister Busygin in his Izvestia article:

"One can half understand the minister who does everything in his power to prevent his combine from changing over to pollution-free production. He doesn't want to lose the profit for his department, he has his plan and his own arithmetic. But, may I ask, where in the minister is the son of the fatherland?"

Rasputin did not put that question directly to Busygin in the interview, but he did ask him why the ministry did not simply shut down the pulp plant.

The answer is a classic in the annals of the Soviet Union's rigidly centralized economy. "That is not within our authority. If they tell us to dismantle the combine, we'll do it. It is not up to us to decide. Any change, even in plan assignments, to say nothing of whether the combine is to exist, depends on the U.S.S.R. State Planning Committee," the minister answered.'The State Is Fining Itself'

It is too early to call the growing public concern over the environment here a full-fledged movement. The most active group are writers -- of whom Rasputin, a native Siberian and a master of strong, evocative prose, is the best known. Another key figure in the debate is Sergei Zalygin, editor of the literary journal Novy Mir, who led the charge against the much-debated plan to send the waters of Siberia's north-flowing rivers down to the parched lands of Central Asia.

But so far, in spite of increased publicity, the environmental movement consists mostly of leaders. The official Society for the Preservation of Nature is written off by most activists as a formal organization, with no independent clout and little stomach for the job of tackling the powerful ministries. Unofficial clubs have no status.

Within the Soviet government, the job of protecting the environment is divided among a welter of competing state committees and subministries. Izrael confirmed the problem when he said there is no single picture of Baikal's ecological situation because of the conflicting views of the organizations concerned.

As the history of the previous Baikal decrees indicates, the system of fines also is ineffective since, as one environmental scientist put it, "all it means is that the state is fining itself. In a situation where industry is state-owned, fines are absurd."

Still, the recent changes in Soviet society have brought the debates out into the open. In Irkutsk, the city closest to Baikal, the pipeline has already become a political issue. Activists have gathered about 10,000 signatures on petitions. The controversy even sparked a spontaneous demonstration by local students and an unusual response by the Irkutsk party first secretary in the local paper.

The new wave of activity is a boon to the older activists, who remember times when tackling Minlesbumprom was politically risky. "Before glasnost, it was more difficult," said Mark Sergeyev, a local poet. "People wrote occasional articles, but no one paid any attention." NEXT: Building a new Siberian rail line