There is something infectious about the enthusiasm of schoolchildren. So here we were on the banks below the Great Falls of the Potomac in a driving rainstorm with the trees blowing and thunder crashing. It got so heavy at one point that I had to put Herb Sachs' raincoat over my head. Fortunately Herb, the director of the Interstate Commission on the Potomac River Basin (ICPRB), wasn't in it; he had another with a hood. And through it all, the kids were having a great time.

What had brought this diverse group of teachers, students, scientists and bureaucrats together that soggy afternoon was the shad or, more specifically, the chance to take part in the release of more than a million shad fry into the river, from where they would try to find their way downstream to enter the Chesapeake and the Atlantic Ocean. Shad are an anadromous fish that historically spawned in the rivers of the Chesapeake in great numbers. Records of the 19th century talk of catches in the millions of fish during the annual shad runs up the rivers - fish returning after three years or more in the Bay and ocean.

There is plenty of evidence that when water quality is improved the shad will return; this has happened on the Delaware and other watersheds in the East. But another reason why shad and other river species were lost was the construction of dams and other obstructions across the rivers, preventing the return of the adult fish to their spawning areas. The most famous blockages in the Chesapeake watershed are the dams built across the Susquehanna. Agreements have been reached to install fish passages around these dams in the next five years, opening up hundreds of miles of habitat for the first time since early in the century.

The situation on the Potomac was a little different. The 10 miles from Little Falls Dam upstream to the Great Falls don't seem like much of the overall Bay goal to open up 1,357 miles of blocked streams in the next 10 years, but they were an incredibly productive traditional spawning grounds for shad. In fact, in 1959, when Little Falls Dam made passage impossible for returning shad, pollution, overfishing and other causes had already depleted their number so much that few people seemed to care. A fish ladder built into the dam never worked right, so the shad were history above that point.

Until the million fry were released the other day.

Why, you might ask, would anyone do such a thing, with Little Falls Dam still very much in place? The answer is a mix of faith and smart politics. The ICPRB, working with the U.S. Army Corps of Engineers and many other Bay Program partners, is in the final planning stages for a new fishway which promises to be much more effective in allowing the returning shad to move upstream. Construction will take a number of years. So why not, thought Jim Cummins, the Project Director at ICPRB, collect the eggs of some of the remaining females below the dam, fertilize them, tag the fry with dye and release them ABOVE the dam? That way, we'll all want to get the fishway built to accommodate them when they return in three years. And that's what happened, with the help of the U.S. Fish and Wildlife Service and many others. Now that they're on their way south, the pressure is on all of us human-folk to be ready when they return.

Of course, not all of them will make it back. Many will be consumed by larger fish or die of a variety of causes. Some will fall victim to pollution, probably to lack of oxygen in nursery areas caused by an oversupply of nutrients. It was ironic that the release occurred in Fairfax County on the Virginia side of the river. Fairfax is the sole holdout to the Commonwealth's effort to have local governments cooperate in reducing nitrogen from their sewage treatment plants, as Maryland and the District are already moving ahead to do.

And even those fish who make it to the ocean have another big threat from man. While Virginia and Maryland have placed moratoriums on the commercial take of shad in the Bay, both states allow coastal intercept fisheries to continue despite the threat to the species in the Chesapeake. Of course, those fisheries catch shad from other estuaries and rivers as well, so the argument has been that on a relative basis not much damage is being done to the Chesapeake stocks.

Those students turning the valves on the tank truck in the rain the other day just came up with about a million reasons why that type of thinking won't stand scrutiny much longer