Everyone knows trout fishing is mainly a spring thing, but autumn runs a close second. The dry, warm days of Indian summer always get me thinking of trout streams: Blazing colors in the trees; cool, clear, meandering water; trout in their liquid lairs waiting for something juicy to drift by.

It was on such a day last week that Jay Sheppard and I donned waders and wandered down to the Patuxent River near Damascus, where he fly-fishes regularly.

"The stretch where we're going runs four miles between road crossings," said Sheppard, past president of Potomac-Patuxent Chapter of Trout Unlimited and current chairman of its Patuxent River committee. "I don't think you can find a stretch of river four miles long without a road crossing even in far Western Maryland, and this is 25 miles from the White House and 25 miles from Baltimore's Inner Harbor."

Indeed, once we got past the rotting, stripped-out deer carcasses some bowhunters had thoughtfully left for us to admire at the parking lot on Hipsley Mill Road, it was a glorious place to be on a warm November day. We were armed with 3- and 4-weight flyrods and an assortment of sinking flies designed to look like minnows and crayfish, which is what Sheppard has been using for 20 years to lure holdover brown trout up to 22 inches long from the river in fall and winter.

The water was gin-clear and flowing at a comfortable level for wading. Everything looked perfect but for one small problem: no fish!

Truth is, Sheppard had lured me there specifically to show the harsh effects of the record dry summer. Drought killed trout by the thousands in the Patuxent, which went from a burbling, woodsy creek to a series of overheated pools with dry beds between them during the hottest months last summer.

"It was the worst drought ever by far," said Sheppard, a retired ornithologist with the federal endangered species division. "We saw flow get down to about five cubic feet per second back in the 1980s, but this year it got down to a quarter of a cubic foot per second, one-twentieth of the worst we'd seen since we started stocking here in the early 1970s.

"At its worst," said Sheppard, "it was about the flow you'd get from a few garden hoses. Each of the pools became a pond with almost no water coming in or out."

Water temperatures rose to the mid-seventies for weeks on end, he said, and algae blooms gobbled oxygen from stagnant pools at night. Brown trout ganged up in the few holes where a little cool water came in but were exposed in the shallows to predators such as herons, raccoons and human poachers (the Patuxent is a catch-and-release stream but has a long history of poaching problems).

The net effect, said Sheppard, "is we went from about 150 to 200 trout per mile to one or two. In fact, we've found no survivors at all except in the headwaters of the creek above Route 94, where about one in three made it.

"I've had a dozen volunteers out here [in the lower section] since mid-September when the flow recovered and no one has yet to see a brown trout."

Sheppard said freestone creeks such as the Patuxent and Morgan Run in Carroll County suffered the worst. Tailwater fisheries below dams, such as the Gunpowder, Big Hunting Creek, the Savage River, the North Branch of the Potomac and the Youghiougheny, were largely spared as cool water released from the bottom of the dams kept oxygen up and temperatures down.

There also were significant losses on tiny mountains streams in Western Maryland such as the Casselman River, where Sheppard said he saw brook trout ganged up in little pools where cool water seeped in. "You'd see 40 or 50 trout gasping for life in a pool the size of a small cocktail table. It was so shallow their backs were poking out of the water."

If it sounds grim, there's a bright side. Sheppard said the drought seems to have had no effect on the aquatic food supply. Minnows, crayfish and insects remain abundant in the Patuxent and in mountain streams, he said.

The worst news from a D.C. area angler's perspective may be the loss of a fine, close-in fishery on the Patuxent this fall and winter. The state started stocking trout there almost 30 years ago for spring fishing, but no one expected trout to survive the summer.

But the cool, shaded waters supported a population of holdover brown trout that thrived. The 10-mile stretch around Hipsley Mill Road has been designated for catch-and-release fishing since 1980, and has been particularly appealing to city anglers as a place to go in the winter and fall to try for large browns that set up shop in the deep pools.

"A day like this would be perfect," said Sheppard as we sat on a sunwashed rock and stared at the water, looking for signs of life. "There are stone flies, mayflies and midges hatching and the water's nice and clear. But as it is, there's plenty of food out there but nothing to eat it."

Well, not quite. Last month Sheppard and his mates from the Potomac-Patuxent chapter of Trout Unlimited got the state to provide 1,000 small rainbow trout to stock in the river for winter fishing, and I managed to catch one on a woolly bugger in the tail of a deep pool.

Next spring, Sheppard hopes to convince Maryland to stock extra brown trout along with the regular allotment of 2,500 or so. Assuming the drought is not repeated, the fall and winter fishing should be good again next year and in a couple of years survivors of next spring's stocking should reach the 22-inch range and provide big-fish thrills to those lucky or skilled enough to hook up.

"The good thing is, there are plenty of groceries here, so whatever gets planted should grow fast. When the Patuxent was first stocked in the 1970s, those fish grew from nine or 10 inches to 15 to 16 inches in a year-and-a-half," Sheppard said.

Meantime, winter anglers in the D.C. area should look elsewhere for their big-fish fun this fall and winter--probably the Gunpowder or Big Hunting Creek.