The birds could finish them off.

Missouri River watermen, hastening to their destinations before court- ordered temporary curbs strand their cargoes, fear that nesting birds may prevent them from coming back this year.The first blow was South Dakota's interim court victory against the release of reservoir water to sustain river levels. That will soon leave sandbars exposed and likely to attract two protected species of bird. If the birds begin nesting there, a further set of prohibitions will come into play.

"If this decision is not reversed, we will be shut down," declared Don Huffman, executive vice president of Phoenix Towing Co. of St. Louis, Mo.

He and others who depend on this river's already shrunken commerce think they have only a few more days for an emergency appeal to do any good.

Otherwise, they may be off this waterway all summer.

The shutdown leaves Missouri River shippers only the option of higher- priced rail freight for long hauls.

"Railroads will have a heyday," said Roger Blaske, president of Alton, Ill.-based Blaske Marine, another of the Missouri's few tow operators.

An official at Burlington Northern Railroad said absorbing this river's low volumes should not affect rail freight rates much, although shippers near the river would see their freight bills rise just because rail is more expensive.

The BN official was also watching to see if reduced flows from the Missouri might ultimately hamper traffic on the crucial Mississippi River.

Federal District Judge Patrick Conmy in Bismarck, N.D., ordered the U.S. Army Corps of Engineers Wednesday to reduce water releases from a key upstream reservoir until June 1.

That immediately began shrinking the northernmost Missouri River barge channel at Sioux City, Iowa. Watermen quoted corps forecasts that even Kansas City water levels may fall too low by next week.

Montana, North Dakota and South Dakota sought the order, with the latter state arguing that falling reservoir levels would destroy its fish spawn for a third straight year.

Now, the barge industry and its shippers fear two species of federally protected birds will nest on exposed sandbars in the next three weeks, preventing the corps from bringing water levels up again for barge service in June.

And the birds, once nested, won't leave until mid-August.

So unless the corps can get the restraining order lifted quickly, "the net effect is, this season's over until Sept. 1," said Mr. Huffman.

That would still leave two months of the river season, he noted, but "we can't go back up for two months."

So tow operators, shippers and terminals scurry to move millions of

dollars in boats and cargo off the Missouri this week before what one called ''the brown wave" - the tail end of navigable water - sweeps through.

"We're going to move things out of harm's way," Mr. Blaske said.

The sudden drop in water levels threatened some barges that were unloading cargoes upriver.

"There are six barges in Sioux City I don't think we will be able to get out," he said, adding they may be there all summer.

Although the lightly traveled Missouri was already hampered by draft restrictions due to drought-induced low water, its cheap service kept overall freight costs down in the nation's prime grain region.

While the Missouri handles a relatively small amount of tonnage, "it's crucial . . Think about the tons it influences," observed Fred Schrodt, vice president for transportation logistics at the big Farmland Industries Inc. cooperative in Kansas City. Mo.

His freight costs near the river "are a full $10 a ton cheaper" than away from it, he said.

Reports said some Nebraska farmers were immediately offered 3 cents to 15 cents less a bushel, as grain companies tried to offset higher freight bills to keep their export grain competitive at port destinations.

Industry officials suspected the northern states, by taking legal action at this time, counted on the birds to stretch a May shutdown over the whole summer.

But John Guhin, deputy attorney general of South Dakota, disputed that view: "There is no reason we would want to shut it down all summer. We would have no reason to do that."