Jack Lorenz figured he was making a big sacrifice when he moved to Washington six years ago.

Lorenz came here from Missouri to take a job with the Izaak Walton League (IWL), which on the surface sounds like a great forward leap for a fishing fiend.

But he had to give up his cabin on Jack's Ford, a stream in the Ozarks that he considered to have some of the finest smallmouth bass waters in the country.

He kept groaning until he poked the bow of a canoe into the South Fork of the Shenandoah River near Rileyville one day.

End of complaints.

"We found a smallmouth Valhalla," said Lorenz, who today is executive director at IWL.

"I had never seen smallmouth fishing like that in my life except once, when I was 12 years old on the Buffalo River in Arkansas.I haven't been back to the Buffalo since, but I'm going back this year to see if it really is as good as the Shenandoah."

Lorenz found his haven in the Blue Ridge in a one-mile stretch above and the one-mile stretch below Compton Rapids, which is about halfway between Luray and Front Royal on the Shenandoah's South Fork.

"I'm telling you, it's the fishiest stretch I've ever seen," he said last week as we nosed the car out Rte. 66 on the two-hour drive.

This is high smallmouth season in the mid-Atlantic states. The rivers are down from high spring runoff conditions, the water is clear, the navigation is easy and the fishing is, in a work, formidable.

Lorenz had made arrangements for us to put in our johnboat at a little campground 10 miles south of Front Royal on Rte. 340. But he couldn't wait for the boat launching.

"Wait a minute," he said. "Let's try this pocket."

We were just above Comption Rapids, which is a favorite spot for white-water canoe enthusiasts. River grasses poked out into a quiet eddy and the surface was dimpled from feeding fish.

He started casting a floating minnow lure and I threw a little spinner-bait. There is no finer sign in all fishing than a fish on the first cast. I had one -- a fat redbreast sunfish, bigger than average, its bright orange underbelly gleaming in the morning sun.

Back it went.

All fish caught that day, and there were plenty, went back because the South Fork is off limits for fish-eaters by state proclamation. Thirty years ago a factory in Waynesboro started dumping mercury in the river. Two years ago it was discovered that South Fork fish carried excessive amounts of the heavy metal and eating them was banned.

Lorenz, who no longer fishes for food anyway, thinks that's all right. "I'd say the fishing today is even better than it was six years ago," he said. "I don't know if it's because of the ban or not.

"I do know that this is a fertile piece of water." He turned a rock over and looked on the underside, discovering helgramites, crawdads and other little critters racing around wildly.

"You do that in one of those clear Ozark streams and you won't find life like that," he said.

We fished upstream first, slipping silently against the current on the power of the electric trolling motor. Then we drifted back, tossing lures against the bank. Within a half-hour we'd found a combination that worked -- white Mister Twister spinnerbaits the bass couldn't get enough of.

They were small fish but thunderously numerous. And few fish fight with the scrappy tenacity of smallmouth and big bluegills. We'd landed about 30 in three hours when we stopped counting.

"We could quit right now and I'd call it a success," said Lorenz.

But we didn't quit. We kept on until exhausted, then turned for home, empty-handed and satisfied.

The South Fork, for all its mercury, remains a spectacular place to fish or canoe.

Just below Compton Rapids there is a 150-foot bluff and in the afternoon Lorenz plunked himself in an innertube and bobbed along the high wall, dandling his feet in the cool water and catching more bass and sunfish.

All day crowds of canoeists crashed over the rapids, led by guides from a number of outfitters that work the South Fork, including Shenandoah River Outfitters and Route 340 Outfitters.

The river almost seemed overused, what with campgrounds every three or four miles and canoeists every half-hour.

"Ruin this stretch? I don't think you could," said Lorenz. "There's just too much good water in here. I watch the people who fish here and they mean business. But the river just seems to get better and better."