Mention the term ''endangered species'' to a group of Americans and the likelihood is strong that someone will remember the brouhaha involving the tiny snail darter and Furbish lousewort, both involved in major environmental disputes over the building of dam projects. But whatever view one holds on the relative importance of the two species involved, the significant point is that not too many years back consideration would rarely have been given to the impact of construction projects on the plant and animal species that might happen to be in the way.
The difference between ''back then,'' and now, of course, is the passage of the landmark Endangered Species Act in 1973.
That act, which is designed to protect wildlife threatened with extinction, expires Oct. 1. Not surprisingly, a political battle is now raging over what to do with that law. Interior Secretary James Watt is urging that the present act be extended for one year, rather than the usual three years. Mr. Watt would then have lawmakers enact major changes in the legislation next year - alterations that would make it easier for industry groups to claim exemptions if they faced difficult economic problems. Environmentalists would like the act strengthened.
Republican Senator John Chafee, chairman of a Senate environmental subcommittee, would seem to be still on target in his assessment made late last year that the ''burden of proof'' is on the Reagan administration in seeking major revisions in the act.
The original legislation, it might be recalled, was amended in 1978 to take account of the legitimate concerns of business groups by allowing projects to go forward if it was found that the benefits of the project outweighed any gains resulting from protecting a species.
Since its enactment a decade ago -- under a Republican administration -- industry has learned to work within the legal mandates of the legislation. That is not to say that the act could not be tightened somewhat regarding procedural matters, such as those sections involving hearings and determinations as to whether a specific species is or is not to be considered ''endangered.'' But what seems beyond dispute is that the basic thrust of the act as amended -- the need to strike a balance between protecting species endangered by the encroachments of modern society while at the same time recognizing the valid benefits of some construction projects -- should not be fundamentally altered.
It is now estimated that some 1,000 species a year are becoming extinct. Given the acceleration of industrial civilization, that rate could even reach 10 ,000 a year by the end of the century. That translates into an extinction rate of more than one species every hour.
It could hardly be in the public interest to sanction such a profound tampering with the environment. There is also the practical consideration that the species in question may have a potential not currently known.
Another point might be briefly noted. That is that the Interior Department has been reluctant to place animals and plants on the endangered species list this past year.
Congress should ensure that such a direct flouting of the intent and purpose of the Endangered Species Act is not allowed to continue.