Poor President Carter. He made the 400-mile round trip to Virginia Beach last weekend and ended up catching a few bluefish in the ocean. You can catch bluefish anywhere.

Nobody told him that he could have gone 10 miles further and enjoyed some of the finest flyrodding for big largemouth bass in the nation.

Nobody told him about Back Bay.

Back Bay is Virginia's 25,000-acre pond behind the dunes. It's just a small piece of the huge freshwater lake that extends deep into North Carolina, where they call it Currituck Sound.

Once Back Bay was famous for its great bass fishing and superb water-fowl hunting. Then beach developers stepped in and fouled things up. Now the Bay is back to what it used to be.

Heaven.

One of the highlights of a trip to Back Bay, which is not exactly on the main road, is the final stop at Ma and Pa Lovitt's boat house at Pungo.

Pa died a year ago and now Ma, aged 83, is running the tumbledown bait and boats enterprise on Muddy Creek. She ought to know how. She's lived here since 1917.

Sonny Gregory is the chief guide working out of Lovitt's. He doesn't overwhelm his clients with gracious hospitality.

"That's your standard 6 a.m. greeting.

By about 6:30 he's likely to be berating you from the back of the boat. "Set that hook, son. That's a big fish. You ain't gonna see him again today."

A colleague and I worked over the marshy shorelines and shallow bays of Back Bay for a day and a half last week just after the presidential party retreated to Washington. We kept track of the bass we put in th boat.

At the end of first day we had 54 bass boated, most in the one- to two- pound range but at least a dozen that ran two to four pounds.

A good deal more than half of these fish were caught on a fly rod with a tiny popping bug, which is a little like roping a bull with a yo-yo.

There's no telling how many got off. We never counted them.

We thought we were just about the cat's meow when we pulled back into Lovitt's in the early afternoon. We had saved out the biggest half-dozen and set the others free.

We arrived about the same time as Robbie Robinson, who came down for the day from Chesapeake, Va.

"How'd you do?" Robinson asked.

"Fifty-four bass, a pickerel and a few big bream," we said, grinning.

Then Robinson pulled his stringer out of the boat. Two six-pounders and a bundle of three- and four-pounders.

Gulp.

"What'd you get them on?" we asked.

He held up a little pooping bug and a fly rod.

Next morning, after the standard berating, Gregory announced he was taking us where the big fish were.

"We're going to the grass beds," he said.

Zoom.

Ten minutes later we were watching the sky turn from black to gray and the fog roll in over the barrier beach and the marsh.

Back Bay is never more than about three feet deep and most of the water is dominated by weeds called Eurasian milfoil. They rise to the surface and wave in the gentle flow like suspended lace.

"Throw that lure out over the grass and work it back fast," Gregory said.

We had switched to Johnson golden minnows - spoon lures - with a plastic worm attached to the hook. We threw out and cranked them back across the surface so they looked like minnows in frenzied flight.

The bass liked that.

They came up out of the grass and boiled the water behind the baits, throwing wakes.

We missed a few of them, too, but before an hour had passed we had two giants in the boat. They came up out of the milfoil and leaped as they swallowed the golden lures. It was a sight I went to sleep that night reliving.

One weighed five pounds, the other 5 1/2.

Then we went back to the shorelines and picked up another couple dozen before we called it quits before noon.

Not bad.

There's a complicated tale behind the current state of success at Back Bay.

Twenty years ago the bass fishing and duck hunting had fallen way below old standards. Most local folks like the decline to Sandbridge.

Sandbridge is a narrow spot in the sandy barrier beach below Virginia Beach. For years it was broken by gaps created by storms. When the storms hit sea water slashed through and washed into the lake, making it brackish.

During those years there was excellent aquatic growth in the bay, providing food for ducks and cover for bass.

Then Sandbridge was built. Pilings were driven in the cuts in the beach and a fence was twined between the pilings. Soon it filled in with sand. The saltwater instrusions were checked entirely in the early 1940s.

The fresh water flow into Back Bay had increased as land was cleared for farms. In a few years the bay became a muddy, and barren. Fishing and hunting fell off dramatically.

For years the locals battled over what to do. One theory was to pump salt water back in and restore the balance. In the early 1960s the city of Virginia Beach gave that a whirl, putting together a pump that Gregory said pushes in 1 1/2 million gallons of salt water a day.

About the same time the milfoil grasses started appearing and since then they've about taken over the lake, driving outboard motorists to distraction and hunters and fishermen into fits of chuckling.

Whether the salt water or the milfoil, which never existed here before, brought the fish and birds back is a matter of debate. Jack Hoffman, head of the Virginia Fish Division, says he doesn't know and wouldn't dare guess. He just knows it's better now.

Better for bass flyrodders, for sure. Because the lake is so shallow the bass almost always seem willing to take top-water lures like popping bugs. And there is no thrill like watching one's bait get smashed and swallowed by a big fish 20 feet away from the boat.

There's one time when that doesn't happen. A southeast wind knocks fishing into a cocked hat. No one knows why, but they all agree it's true.

"Southeast wind said Gregory, disgustedly. "You can't even catch a cold on a southeast wind." CAPTION: Picture, Robbie Robinson of Chesapeake, Va., shows Back Bay prizes. By Angus Phillips - The Washington Post