HAVE DAMS and highways become endangered species? You might conclude that from some current attacks on the Endangered Species Act. Unless that law is drastically modified, some critics say, nondescript plants and tiny creatures are likely to be used to block a vast - but unspecified - number of vital public projects.

Such fears are overdrawn. The potential for conflicts may be fairly large, but in all cases where goodfaith consultations have been made, they have produced accommodations that allow a project and an endangered species to coexist. In Maine, the Corps of Engineers has apparently found a way to transplant the Furbish lousewort, a rare snapdragon that had gained notoriety as a possible bar to the controversial Dickey-Lincoln Dam. In other cases, life-saving results have been gained by changing a project's site, design or operations somewhat.

The consultation process has worked so well so often partly because federal agencies have had no alternative; the 1973 law flatly bars them from destroying an endangered species or its critical habitat. Now there is a real danger that changes - this week in the Senate or later in the House - could reduce or eliminate incentives to negotiate, and bring on a rash of projects that not only run roughshod over fragile species, but are environmentally less sensitive in general.

Flat exemptions for some projects would obviously have that bulldozing effect. We see much less cause for concern about the last-ditch arbitration mechanism in the Culver-Baker bill now on the Senate floor. One of its crucial elements is that the proposed review board could not even consider exempting a project unless it was satisfied that consultations had been genuinely pursued without success. That point would be made even more emphatic, and the process tightened in other ways, by several amendments that Sen. Gaylord Nelson (D-Wis.) has prepared. We urge the Senate to adopt them. They would promote the creative review that can minimize out-and-out collisions without sacrificing either species that should be saved or projects that are generally worthwile.