IN ALL THE ARGUMENT over the Endangered Species Act's potential for blocking public works, many people have lost sight of the fact that ways can usually be found for fragile species and big projects to coexist. The latest encouraging example of accommodations involves the Grayrocks Dam in Wyoming and the most carefully nurtured of all endangered species - the whooping crane.

Along with large flocks of geese and other wild fowl, the cranes - now numbering 75 - use a stretch of the Platte River in Nebraska as a stopover on their annual migrations between the Gulf Coast and the Arctic Circle. The Grayrocks Dam, part of a $1.6-billion power project almost 300 miles upstream, threatened to disrupt the birds' habitat by reducing the flow of the Platte. After wildlife organizations and the state of Nebraska went to court to stop the dam, its friends in Congress this fall tried to exempt it from the Endangered Species Act. Congress finally directed the new Cabinet-level committee on endangered species to settle the matter within 90 days.

Now, even as the federal reviewers are starting their work, the parties to the suit are wrapping up a proposed out-of-court settlement. The utility, the Missouri Basin Power Project, has agreed to release specified amounts of water from the dam, and to put several million dollars in a trust fund for the purchase of water rights, maintenance of crucial sandbars and wetlands, and other steps to protect the birds' staging area.

This strikes us as a constructive plan with an innovative feature, the trust fund, that could be adapted to many situations where wildlife habitats are threatened by development. The program's success does depend heavily on Nebraska's willingness to help secure the necessary water rights and ensure that the water actually benefits the birds instead of being diverted to other uses. The courts and the federal panel, headed by Interior Secretary Cecil D. Andrus, might well want reassurances on that point. In general, though, they should welcome this initiative and do everything possible to help it work.