It was late Wednesday afternoon, May 23. I was wading knee-deep in a small New England river. All afternoon, caddis flies had been coming off the water in steady numbers. Though not breathtaking, it was certainly a decent hatch by any standards. I had already caught three nice brook trout, all wild and more than 14 inches. I had also lost three more, one of which was 20 inches or more and fought me for several minutes in a deep pool cut by whitewater.
Then, around 5 p.m. something changed. Whereas most of the afternoon there had been dozens of caddis flies visible skittering along the surface of the water, or hovering in groups in the bushes — and in brief flurries of activity they had appeared in the hundreds — suddenly they started coming off the water so thick it was like fog.
The numbers of caddis flies that were soaring upstream a few feet above the water went from dozens or hundreds up to thousands and even tens of thousands. I have caught trout in 25 states on some deservedly famous rivers and have never before witnessed a caddis fly hatch to rival this one.
The river was the Magalloway. Its headwaters flow off the ridgeline on the Maine-Canada border in northwestern Maine in the Rangeley Lakes region, an area of several large, deep, remote, wilderness mountain lakes, many of which are 10 miles long or more. These are the holy waters of brook-trout fishing in the United States: waters still containing wild brook trout that have never been bastardized by stocked brood.
Mooselookmeguntic is the largest of these, and most famous for its huge brookies, but there is good trout and landlocked salmon fishing throughout the region’s lakes and rivers, which include not only the Magalloway River, but also the Rapid, Cupsuptic, Rangeley and Kennebago rivers, as well as several smaller but still notable streams. And, of course, the numerous lakes and ponds.
Coming off the high ridges, the various branches and headwaters of the Magalloway soon meet in the remote Parmachenee Lake, out of which they flow through a short stretch of woods and into Aziscohos Lake. At this point, the Magalloway has picked up about all the water it will get. It spills out of a small dam on the Aziscohos and plunges through a few short wooded miles of whitewater down to the town of Wilson Mills, Maine.
There the river suddenly slows, changing from kayak water to family canoe-trip water. It wanders another dozen or so miles through meandering S-curves along the border of Maine and New Hampshire, through wilderness preserve loaded with moose and waterfowl, before it flows into Lake Umbagog and becomes the Androscoggin River.
It was in that short stretch between the Azicohos Dam and the famous Wilson Mills bridge, and the few hundred yards just downstream of the bridge, that I spent two days fishing with my friend Rich Warren, who I knew from the New Haven River Anglers.
Rich had just recently retired from many years teaching at Vermont Technical College and was celebrating with the second of several fishing trips. I was happy to take part in the celebration by spending a few days with him chasing wild Maine brook trout.
Though water was running high — the measurement at the dam was about double the flow I would have considered a good amount for that stretch — it was the ideal time of year and weather was good, so we were expecting some good fishing. I just didn’t know how incredible the caddis hatch would be.
I had fished that stretch of river a few times in the past. I had seen some pretty good caddis hatches in mid-June 50 miles south on the Androscoggin. In fact the previous day we had fished the Androscoggin in the afternoon, and I had landed 18 trout. Rich landed quite a few also. But they were mostly stocked, and they were only in the 10-to-14-inch range. We were looking forward to some larger and wilder brookies on the Magalloway.
Most of the day on the Magalloway presented challenging, technical fishing. Like most of the rivers in the area, it is designated as fly-fishing only, with restrictive creel limits. This protective approach to management has resulted in a blue-ribbon fishery that attracts lots of fly-fishermen. The fish see plenty of flies in their lives, and they are leader-shy. Sloppy casting or the wrong flies put the fish down pretty quickly. 
But when the air temperature on that late May day rose up into the 80s, it apparently created the perfect conditions to stimulate a caddis hatch for the ages. For the next hour, the fishing was fantastic. When the hatch began I lost about 15 minutes of time moving several hundred yards down river avoiding other anglers and some stretches of river that looked either less promising or less accessible in the high water.
Then I finally found a nice patch of water that I had to myself. I proceeded then to land three brook trout in 30 minutes, doubling my take for the day. All of them were over 15 inches, with dark healthy skin and bright red and yellow spots. All took my fly hard, and fought like the strong well-fed wild fish that they were. The hatch, and the flurry of trout activity, was incredible. Then it was over, and the fish stopped biting.
We returned to the same stretch the next afternoon, expecting a similar hatch. A few caddis flies came up, enough that if we had not been there the previous day we might have said it was good hatch. But it was nothing compared to what had seen. Indeed, we might never be in just the right place at the right time again to see what we saw.
The fishing was slower too. We fished from 3 until 7 p.m., when we had to start the four-hour drive back home to Vermont. I landed only two trout, with my consolation being that the larger of the two was just short of 20 inches, among the best brook trout I have ever landed. 
For most Addison residents, the drive to Wilson Mills is less than four hours. This holy water is probably the closest place you can go to catch wild brook trout that will routinely top 15 inches. Well worth the trip. Bring a friend.