Some call it ''Earth Wars.'' It's the battle to protect America's land, air, and water for future generations. Leaders of the environmental movement say they are hard pressed, but holding their own against the Reagan administration's attempt to adopt what it terms a more ''balanced'' environmental policy.
During the 1980 presidential campaign, candidate Reagan promised to strike this balance - ''not blindly seeking growth at terrible cost to the environment, '' nor ''so excessively pursuing 'environmentalism' '' that the nation's economic health is endangered.
The administration consistently has followed these goals. The President wants a diminished role for the Environmental Protection Agency, speeded leasing of federal land for energy and coal use, more timber harvested, and a return to the states of the main environmental protection duties.
The Reagan team already has weakened federal enforcement, regulations, funding, and research on the environmental front.
Environmentalists call the cumulative impact of President Reagan's policies, to be played out in future years, ''devastating.'' This is so, they say, particularly when coupled with the administration's clear tilt away from energy conservation and toward energy resource development - which will increase pressures on the environment.
But with the help of Congress and strong public support, basic environmental protection laws have escaped revision during theReagan administration's first year, they say. These laws actually could be strengthened in 1982.
''We're not at all demoralized,'' says Richard Ayres, lawyer for the Natural Resources Defense Council (NRDC). ''The Reagan attack on environmental laws has been so sweeping it has spotlighted public support for environmental action.''
Mr. Ayres's view - that environmentalists are hard pressed but not routed, and could rally - was typical of eight environmental leaders surveyed by the Monitor on Reagan's first-year achievements. Their groups' memberships are growing - the Sierra Club alone up from 180,000 a year ago to 270,000 now. They cite opinion surveys showing the public wants no retreat from high environmental standards and enforcement. Environmentalists sense that the political wheel again will turn in their favor. Many Republicans in Congress favor environmental values. And environmentalists anticipate help in election year 1982 from the Democrats, the party most sharply identified with protecting the environment - by a 56 percent to 22 percent margin in a new ABC-Washington Post poll.
''During the 1970s a dozen major environmental statutes were passed,'' observes Jonathan Lash, president of the Energy Conservation Coalition and an NRDC lawyer. ''Those lay out mandatory duties for the federal government and for individuals and private enterprise. In the year that the conservatives were supposed to have taken over, that the country was supposed to have retreated from environmental values, that we were getting hardheaded and only looking at business - not one of those statues has been changed in any way. The Congress, after it began hearing the public response, has refused to pass a single amendment to environmental legislation.''
Congress went through a number of months in 1981 ''where they just sort of laid down and played dead while the attention of the country was on tax cutting and budget cutting,'' says Russell Peterson, president of the National Audubon Society. ''Now Congress is just really warming up to the fight. Next year the key battles will be over the Clean Air Act, the Clean Water Act, and the Endangered Species Act. I anticipate many of those laws will be strengthened.''
Mr. Peterson and the others expect no relenting on the Reagan side, however. ''The Reagan administration is having a devastating impact on the governmental institutions established over the past 12 years to protect the environment,'' he says. ''That problem stems directly from the President. They tried to carry out a coup in the environmental area by destroying the institutions, going all out for development of the public lands, dismantling the enforcement function.''
The administration has stripped the Council on Environmental Quality - a White House early warning system for environmental trends - down to a few caretakers.
Reagan also has cut out long-term health and safety research and environmental impact studies on the $20 billion synfuels program, notes Mr. Lash. ''They have delayed already overdue action on toxic water pollutants,'' Lash says. ''In EPA regulatory actions since January under clean air, water, and toxic substances acts, they have canceled 40, completed action on one, initiated 18 new proceedings - a dozen of them to weaken existing regulations. States cannot get review of modifications of state implementation plans. So what the administration is doing is undoing - delaying, canceling, and weakening.''
Congressional leverage is limited. Congress can draw tighter regulations, says Ayres. ''But there's so much to keep up with, so much discretion for enforcement, that it's hard for Congress to control it,'' he says. Similarly, Congress can appropriate funds for environmental protection. But if Reagan does not spend it, several years of court fighting could pass without action.